DEVELOPMENT OF UNDERGROUND CIVIC FACILITIES IN DELHI – A CRITICAL ASSESSMENTAuthors: Dr.A.K.Dube, Anand Kumar Pandey

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Table of Contents

Chapter

Summary

1. Introduction

2. Literature Survey

3. Problems of Delhi

4. Geology of Delhi

5. Geotechnical assessment of Delhi sub-surface

6. Transport Underground

7. Storage of Water Underground

8. Planning and Design

9. Legal and Societal issues

10.Conclusions and Recommendations

11.References

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SUMMARY

The objective of the study had been to critically evaluate the possibilities of developing some underground facilities in Delhi. The problems of Delhi had been gone into details and enlisted the traffic and water scarcity in the city to be most important. The study has therefore been centered on evaluating the possibilities of these two problems of Delhi.

Any project involving underground planning, designing and construction needs enormous data about the geo-engineering characteristics of the soil/ rocks to be encountered while working. The data generation and collection is a difficult task. Numerous reports prepared for various construction activities have been obtained and studied in details. The data obtained is rather very sketchy and may not be good enough for designing.

Several transport tunnels have been conceptualized to help in easing the traffic problems in the thickly populated areas of Delhi. An underground ring road has been conceived to connect busy areas of Delhi with trans Yamuna areas. Submerged bridge idea has been proposed for river crossing. There are over 3000 such bridges all over the world in costal cities and in cities on the banks of rivers.

Many road tunnels have been suggested to connect different places where high volume traffic passes. The proposed alignments are indicative only. They can be fixed up after conducting detailed investigations about traffic and sub-surface soil/ rock conditions. Car parking is another serious problem. Underground car parking may be possible in rocky areas. Conceptual designs have also been suggested for car parks.

Underground water storage scheme has been suggested. The flood water of Yamuna can be interned in to a system of tunnels and stored there. This water can be pumped out from places where needed. The storage scheme includes intake structure, a tail structure and main tunnels and a net work of storage tunnels. There will be a number of shafts which will help in the construction of the system. These shafts can be used for pumping out of water and maintenance of the system.

The underground storage system is also a conceptual noval idea. There is no such system ever built any where in the world. There is a need to refine the concept by generating reliable data for designing a system. With the help of the scanty data available, some basic design has been done about various sizes of tunnels. Appropriate temporary and permanent support system have also been suggested. A general plan has been proposed which includes possible locations of main components on a scaled map of Delhi.

The study has concluded that the road tunnels are feasible in a busy city like Delhi where no surface space is available for laying wider roads for ever increasing traffic volume. These road tunnels will help in improving the landscape of Delhi which has been affected very much by numerous fly overs. Underground car parkings in business districts will help in reducing congestion.

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The underground infrastructure concept will reduce pressure on land and may help in saving what ever little greenery left in the city.

The study is conceptual in nature and needs to be refined by further investigations about subsurface soil/ rock behaviour and traffic scenario. The Delhi master plan should have a chapter on subsurface utilities. This plan may help in reserving locations and fixing priorities for future sub-surface development.

There is a need to develop legal codes for under ground space development. The ideas proposed are new and there is a need to debate about them so that they can be adopted by the society for use to improve the quality of life in over grown metropolis of the country.

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CHAPTER - I

INTRODUCTION

Population explosion, specially in a developing country like India, is giving rise to urbanization in most unplanned manner. The cities are sprawling at a very fast pace and urban population is growing in leaps and bunds. At the dawn of independence, Delhi had a population of a few lacks. Today it has 140 lacks people living in the progressively growing city. The growth is not following any definite pattern and any infrastructure built for the needs of the people, soon become inadequate and out dated. The urban growth swallows the agricultural land and vegetation around and the city gets converted to a concrete jungle affecting the environment, landscape and the society. The developed countries adopted the use of underground space to cope up with the shrinking land available for development. Delhi is now poised for underground space development to alleviate the problems of its citizens in the years to come.

The author submitted a research proposal to the Council of Scientific and Industrial Research (CSIR) under the Emeritus Scientist scheme is early 2000 to study the problem of Delhi and to evaluate the possibilities of developing underground space to supplement the infrastructure facilities which are under stress and may continue to be so in the years to come.

The author started the work in July 2000 from the premises of the Central Road Research Institute, New Delhi. The information on the needs of Delhi, had been collected and an effort was made to develop a subsurface map of Delhi, which may be very important for planning and designing of any subsurface facility. General maps and toposheets of Survey of India had been accepted as information base for the work. Huge data base is needed for subsurface works which is difficult to find. Hence ideas expressed are conceptual in nature but they can be refined further by additional data collection at a later date.

Transport and water are the two most important needs of the city as revealed by the study. These two issues had therefore been evaluated in more details. The information available on these issues are very scanty and are based upon some publications and newspaper reports.

Literature survey had been done for these two sectors only. Transport and water storage underground may be possible. Transport infrastructure which includes parking also is very inadequate in the city and it may be difficult to cope up with the ever increasing numbers of motorized vehicles added every year. The wide roads are not possible in built up areas and the fly overs become inadequate soon after their construction. The newly introduced metro may or may not wean away the Delhi motorist from his favourite vehicle.

Water is another problem of Delhi. Delhi has no source of its own except fast depleting groundwater. A large part is obtained through neighbouring states, who may or may not fulfil their commitments in future. It may be possible to store the flood waters of Yamuna below ground. The flood water is free from any interstate agreement and most unwelcome, and a potential flood threat to riparian states.

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The underground facilities are costly to built but cheaper to maintain. Where no surface solution works only the underground solution works there. Underground facilities are unconventional and society may not accept them easily. They may be apprehensive about their viability and safety. The subsurface soil/ rock has to be suitable for construction and there may not be any fears of subsidence or damage due to any cause. Water inrush, earthquake, vandalism and terrorist attacks may be some of the fears. The appropriate technology for construction and cost may be other causes of concern.

The proposed facilities discussed in the report have been evaluated from all normal angles and attempts have been made to answer some of the questions which may arise. The issue of metro has not been discussed as it is becoming a reality in Delhi.

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CHAPTER - 2LITERATURE SURVEYGeneralLiterature survey is a very important matter for any scientific study as it gives us the historical development of the subject and we can learn a lot from the experience of others. In the following paragraphs only very important references have been given which are found to be useful for the development of the subject. The review is restricted to road transport and water storage underground only.

Water storage

International

The literature is very rich on the subject of transport infrastructure and storage and transport of water underground. The transport of water through via-ducts dates back to Roman times where water was brought through tunnels and aquaducts for Rome from long distances. Around year 300 A.D.(the peak) the system consisted of 11 aquaducts which carried 1,608 billion litres of water per day. The whole system was 460 km long and 350 km was through tunnels. The per capita supply was 900 litres per day per person in Rome. Many adequaducts have been described in the literatures but it is not possible to refer to all of them. Hence only predominantly underground aquaducts are being refered to briefly is the following paragraphs.

Aqua Anio Vetus was about 60 km long and most of it was underground. It was completed in 269 BC and supplied water to eastern part of Rome. The water supply was 182.51 million litres per day. Aqua Mascia, completed in 144 BC, was 87 km long and the capacity was 194.365 million litres per day. About 90% of its length was through tunnels. Aqua Alsientna was built in 2 BC by Angustus. It was about 30 km long and wholly through a tunnel. The aquaducts carried 16.228 million litres of water per day. The water was for a lake used for naval exercises.

With the fall of Roman Empire, the aquaducts also went into despair. They were shut down by Goths who carried troops through tunnels to attack Rome. There were efforts later to repair them but were ineffective. Most of the aquaducts withered out except Aqua Vigro which remains in use even today.

The ancient Middle East always faced water shortage and the people learnt to conserve the water, so precious to their life. Falaj, also known as qanat, is a tunnel like structure dug through water bearing strata for several kilometres.

In the Falaj system there is a mother well, which is located down stream, acts as a storage. Such stored water is protected against evaporation, percolation and silt accumulation. The falaj carry water to other places from the mother well. The falaj is connected to surface by shallow shafts which are located at about every 20 metres

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distance. The shafts provide ventilation and removal of debris during construction and maintenance. To prevent animals falling in , the mouth of the shaft is firmed up by a ring of burnt clay lid.

The falaj (tunnels) dug from the mother well were small in size, sufficient for men to work in, having a gradient of 1:500 to 1:2500 to prevent erosion and siltation. Crossing one another, was through siphons or bridges. The water was used for other purposes, such as irrigation, washing and bathing.

Transport and storage of water underground had been done by men in the past and there are many historic accounts in the published literature. In the modern times the underground mode had been used extensively for the needs of the society. Going underground (1988) edited by Winquist and Mellgren narrates numerous cases of construction and use of underground space. There is a reference to Siloam tunnel built is in Israel in 7th Century BC to supply water to Jerusalem (Fig.1.1).

Fig.1.1, Silom Tunnel in Israel

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It is 533 m long tunnel excavated in limestone, still in good condition for use even today. The above authors have referred to many modern water conveying tunnels to supply water for the cities. Water of Bolman lake in Sweden supplies water to twelve towns, with a total population of 600,000 (Fig.1.2). Sweden’s second largest city Gotenburg gets its water supply through a systems of tunnels from river Gota Alv.

Fig.1.2, Tunnel for Gotenburg water supply

Water for Sao Paulo (Brazil) is brought through tunnels and pumping station which totals to 25 km (Fig.1.3). The pumping station that lifts the water to 120m is also in an underground chamber.

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Fig.1.3, Water for Sao Paulo through tunnels

Sterling and Carmody (1993) wrote a book “Underground space design” which gives numerous examples of underground space use and development. Many schemes for improvement of urban life have been described and a large numbers of such schemes have been proposed for future.

There are many instances of inter-basin or intra-basin transfer of water but there are very few examples of underground storage of water. Water and sewage treatment underground is being done in many cities like Stockholm, Tokyo, Oslo and Chicago.

Boivion (1990) refers about underground storage of water in Quebee city area. There is a reference of three underground reservoirs made by cut and cover method to store clean water. Des Plaines reservoir was built in 1933 which could hold 150560 m³ of water. It was 233 metre long, 94 metre wide and 70 metre high. Mont Chatel reservoir was the smallest of all and could hold 11424 m³ of fresh water, built in 1964 and measured 55m×48m×4.25m. Another, Du Plateon reservoir was built in 1973 to store 48350 m³ of clean water measuring 87m×87m×6m. The depth from surface is not known for all the three, however they are classified as near surface structures.

National

Transport and storage of water underground was a common practice in forts in the princely states of India. Rajasthan and Gujarat were pioneers of rain water harvesting where the rain water was stored in stepped dug wells in forts and populated areas.

In the modern times, the transport of water through tunnels is very common. Beas- Satluj link project transfers the water of Beas basin in to Satluj through two tunnels, each about 8 metre in diameter and over 14 km length individually. The water is used for hydro-power generation and irrigation of land. Intra –basin transfer of water for power generation is being done in Bhagirathi and Yamuna river basins. In case of Yamuna, the water is diverted through tunnels to generate power at two places. The discharged water is further used for power generation and irrigation down streams. The waters of Bhagirathi river is diverted through tunnels for power generation at a couple of places. There are many schemes in Himalayas and peninsular region where the river waters have been diverted through tunnels. Such schemes are innumerable in India, described in details in the published literature.

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Transport

International

Movement of men and material has a pre-historic origin. Cave dwellers, invented the wheel and this started the vehicular transport. Early man dug underground space with the help of stone and bone tools. The underground construction efforts increased with the introduction of gunpowder in 17th century. Nineteenth century saw the development of rail, roads all over the world. Natural obstacles like hills, water bodies and thickly populated areas were negotiated by tunnelling. Motarised vehicles came into existence in the later part of the nineteenth century. Road transport development started there after and many tunnels were made on roads in hilly areas. The city transport system got first underground railways in the name of London tubes in 1863. These subways are under operation in about 100 world cities and many more are being planned.

In the following paragraphs some important road tunnels are being referred to which cater to the needs of urban areas.

Boivin (1990) mentioned about several underground facilities for motor transport and parking lots in the city of Quebec. He stresses that now the underground space is a part of general planning of a city. In the city there are many car parks, 12 pedestrian walkways and 5 tunnels for movement of cars in heavily builtup areas.

Hanamura (1990) describes the strategy for underground space development in Japan. It is argued that the relocation of existing city structures to deep underground will reduce the traffic congestion on city roads improving urban land scape. Energy efficiency, security and earthquake damage prevention are some of the other advantages.

Nishi, Kamo & Ozawa (1990) also emphasie the use of underground space for improving the traffic problems in big cities.

Cooper (1996), while advocating the creation of underground space for various civic purposes in a city, mentions about some important vehicular tunnels. Phase II of Central express way tunnels, Singapore are 3.7 km and 2.5 km long. The tunnels pass below many important roads, features and important buildings. The north tunnel is dual four-lane, express way 735 m long, with two slip roads comprising 230 m of tunnel and approach structure. The south tunnel is a three-lane express way, 1760 m long, with six slip roads comprising 1100 m of tunnel and 600 m of approach structure. Five slip roads from the underground Havelock interchange, links the express way to the Central business district. The tunnels vary up to 50 m of maximum width. Depth of the tunnel roof is 11.5 m to 27.5 m from surface. Ratchadamnoen road tunnel, Bangkok is located in the historic center of the city and was built to carry traffic during the peak hours through a principal road intersection.

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Anttikoski, Niini, Ylinen and Ruoppa (1994), explore the possibilities for underground space development in Helsinki. They talk about planning many underground routes for vehicular transport and parking lots. Two main road cross-conections and a ring road, mostly underground, are under consideration to remodel the city populated areas.Car Parks

Planning for traffic tunnels in city hotspots is very common and many traffic tunnels are in operation in several mega cities all over the world. In a big city there may be many cars, as many as the people. Usually, the people use cars for travel from home to work place with in a city. The car for most of the time remain idle and there has to be a place to keep it till such time the owner drives it again on a road. The car may therefore need space at the residence of the user and at his work place. Mega cities have normally no space available for such a situation and the owner is left with the option to use public transport. In many cities there may not be good public transport, hence the owner driven car may be the only option. There is thus a need for public car parking. The issue of car parking is an essential part of a city transport planning. Unfortunately, this issue is forgotten while planning. In view of increasing vehicle population, the provision for trouble free parking may be a necessity. In many cities there is not enough free space available for parking cars. This gave rise to consideration for having underground car parking. Many big cities have such car parks and many more may have to follow suite in the years to come. The International Tunnelling Association (ITA) got an international study done on the topic of underground parking. In the following paragraphs resume of this study is being given for ready reference.

The owner driven car had been the center of studies where each car needs at least 12 sq. m of space for parking. In view of space crunch for parking in big cities, the car manufactures are competing with each other to produce an efficient car which can be accommodated in a smaller space. The decision about car park construction is solely dependent upon cost. Other considerations like environment and aesthetics are not taken in to consideration as it is difficult to quantity the benefits in monetary terms. The ITA study group concentrated first on quantifying the advantages and disadvantages of underground car parking. This may help in popularising the concept of underground car parking in populated cities where it may find favour with decision makers to recommend the construction of underground car parks.

The conventional off street and open area car parks are very common. Such car parks sometimes cause traffic problems and it often becomes difficult to differentiate between legal and illegal car parking. Car parks are usually developed by individual companies or the public body of the area. The biggest advantage of underground car park is that it can be built below surface permitting the use of surface space for more lucrative purpose. In the underground the car is protected against harsh weather. It may be high temperature, cold, rain, snow or hail. The underground car park can be as close to the location where owner wishes to park his car. Mont Blac car park in Geneva, Switzerland is dug below the lake very close to the city center. Many car parks may be below a building or many buildings in the vicinity in a busy business district in a mega city, being most convenient to the users. The underground car parks can be decorated, may have

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good signposts, general atmosphere and accessibility to connecting roads, besides being safe. The underground car park is not visible and hence has no visual impact which a surface park in multy storeyed building may have. The underground car parks can be used for civil defence in an emergency.

The underground car parking issue had been studied in many countries by an expert group of ITA. Some of the results of this study are given in the following paragraphs.

Sweden

Stockholm, the capital city of Sweden is endowed with fairly good rock formations down below. The parking problems grew progressively with more cars coming on the roads. The car parking facilities have been considered as part of road transport network. Stockholm ring road (mostly underground), a peripheral cross link and many other improvements for vehicular movement have been implemented, keeping in view the needs for parking. It is understood that direct underground connection to parking lots from freeways will be very helpful in decreasing congestion above ground. The old city has many restrictions on vehicular movement and parking is scarce. In view of congestion, it may be good to consider underground option for transport routes as well as parking lots. In the central city many underground car parks have been built to meet the demands of car owners, reducing car park on street and facilitate pedestrians and traffic flow. Many new underground car parks are planned to be built.

The Narsa Latin Garage constructed in 1988-89 is under a school yard. It can have 200 cars. This can also serve as air raid shelter. Medborgarplasten George is near the most important train station and commercial place. The parking lot was created in an old underground storage which can hold 300 cars. Igeldomn George is constructed in rock to hold 65 cars and be used as air raid shelter during war times. Tegnerlurden garage is built in rock under a park. It can accommodate 152 cars and can be used as air raid shelter.

The construction cost for an underground car park is higher than the surface car park, but its maintenance is very low. The underground garages can operate for several years without any major maintenance cost.

Auastralia

Sydeny opera house car park is a very important landmark in equally important area of the city. It is very close to the Harbar bridge and adjacent to Govt. House and the Royal Botanic Garden. It is the first helical underground parking facility that has twelve stories and parks over 1100 cars (Fig. 1.4). A free stand double – helix concrete structure, wound around a central rock core which links the drives and service tunnels. It looks like huge dough-nut and has an outer diameter of 71.2m and inner diameter of 32m and goes up to a depth of 28m below sea level.

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The facility was constructed under the Botanic garden or the fore court of the Opera House. The construction below ground was preferred so as to prevent any damage to trees within the Botanic Garden. The rock cover is 7-9m and thick over lain by a couple of metres of soil.

United States of America

Large cities like New York, Chicago, Boston and Los Angles have huge vehicle population. The work places, commercial and residential area need parking lots for vehicles. More vehicles add to air and noise pollution, hence becomes a social concern. There may thus be talks of restricting entries of vehicles in thickly populated areas. Denial of parking space may be one option, other by ordering restriction of the vehicular movement. The restrictions on vehicular traffic may affect the commercial and social activities. Hence a balance has to be struck between the environmental concern and commercial and social activities. The provision of underground parking to some extent may help in resolving the conflict. In the recent past there had been development of underground car parks in many big cities and the trend is growing.

In Boston there are a couple of important underground car parks. The post office square underground car park is a result of joint effort by building owners and tenants of the area. They purchased the area and took to develop it through public/ private participation. In 1987, the remodeling and creation of underground car park started and completed in 1990. Above the garage came up a richly land scaped public park. The garage has a capacity of 1400 cars and is easily and conveniently accessed to the region’s highway system. It is well ventilated and profusely lit, having an over all good architectural layout. The open space green with trees provides environmental and health benefits to the people in a very busy central area of Boston.

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Boston’s North Station has been redeveloped to include a 1300 car underground park and a garden areas above the garage. The station is a traffic hub of commuter lines. The garage has five levels and the deepest lies about 20 metres below the surface. Tall office buildings and hotels nearly also use the parking facilities which has helped people greatly.

Japan

Tokyo and Nagoya are large cities having many underground parking facilities. The street side parking is being discouraged due to its interference with the traffic. Surface and above ground car parks are much lesser as compared to 72.3% of underground car parks in Tokyo. In Nagoya 94.2% car parks are underground. Both mechanized and non – mechanized underground car parks are there, though mechanized constitute only 5.6% of the total. Large cities have no free area available for parking, hence construction of underground car parks may be very much welcome in the years to come.

France

France has over 400 underground parkings spreaded over various towns of the country. In Paris the Main Square of town hall has surface as well as underground parking. Many areas are being remodeled and underground parking space had been included. In Marseille, the Etienne d’Orres car park provided lot of surface space for the pedestrians above ground. An underground car park provides space for 80 cars in Louvre. Many surface as well as underground car parks have been connected by tunnel to improve communication.

Societal and Legal concerns

Men underground sometimes because frightening. The person passing through and staying underground for sometime have many inhabitation in his mind. Over all there is a negative feeling about the underground space. The windowless environment sometimes creates fear. People feel concerned about being trapped , deluged or roof crashing due to earthquakes. These concerns sometimes are real and need to be taken care of while designing. The underground living may be ruled out but the use of underground space for many useful purpose may be welcome and the underground space development in the past signifies the man’s acceptability of the underground space with some reservations. Sterling and Commody(1986) have dealt with the issue in details. Not much of data is available about the human behaviour underground, but what ever is available is reassuring. The images of old caves, dangerous mines and closed surroundings arouse fear, uneasiness and timidity. Inspite of all these, the use of underground space is increasing.

Swedish Experience

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Sweden had been the pionear of underground space development in Europe. It began with opening up of underground factories in 1946. Experience with working underground had been mixed initially but later become positive. There had been no physical effect on human body reported so far. However the psychological barrier persists. Sweden and other Scandinavian countries had a long experience of underground space use and it is proving rewarding. Long stay underground is still disliked but short time uses are welcome. The well lighted and decorated space can achieve better social acceptability.

American Experience

In the United States of America the social acceptability of underground space is increasing but still people are not very enthusitic about it. The usual complain about poor illumination and ventilation persisits, however the rejection is waning. In the Kansas city underground space developed in limestone mines, 50 metres below surface, workers appear to be happy about working environment. Majority of them rated the underground space safe and efficient, with better ventilation and lighting. Here also the psychological reasons may be there but with better lighting and ventilation, the underground can provide a convenient place for work.

Chinese Experience

Chinese have network of tunnels and caverns for civil defense purposes, mostly under big cities. Use of underground space for manufacturing, storage and recreation is growing. Most of the underground space is also less ventilated and lighted, which is a cause of concern. This is a reason for dislike for underground work place. There is a need to improve safety standards so that the people may not feel insecure against fire, earthquake and structural failure.

Japanese Experience

Land scarcity in big cities helped in development of underground space in Japan. Safety and disaster precautions had been two important issues for investigations. Here also psychological concerns govern the dislike for underground space. Those who work underground have a better acceptability, however the surface workers are not very enthuistic. Most people have negative feeling and they are more concerned about safety against earthquake and mental anxiety. Probably good environment underground may be very helpful. Some felt like being compensated for working underground.

General Experience

The use of underground space for functions like utilities and stores, where people are occasionally there, may be most welcome. When people move and work around for long hours these, problems are there, hence the need to mitigate the ill effects. The

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underground theatres, museums, libraries, gymnasiums, laboratories and manufacturing plants may also be liked by people as they need noiseless isolation for the type of activity done there. People may like to work on surface as they dislike the windowless space in underground. The activity like the one in underground store, may be encouraging for the visitors and the workers as the scenes change fast, breaking the boredom of the people, small room/space underground give a feeling of confinement. However, more spacious areas seem bit more comfortable. The deeper the space, more uncomfortable it is, as it gives a feeling of going down below by lifts or escalators. A well lit, ventilated and furnished and well finished space helps in overcoming the negative perception of being underground.

Safety is a very important issue for underground space. On surface, the building can be approached from outside for fire fighting, rescue and relief. It is not so in case of underground space where the exits and entries are limited. This limitation calls for extra efforts and hence the design of the underground space is done very carefully to ensure safety of life. Civil and Mineral Engineering Building of University of Minneapolis at Minncapolis, Moscone Convention Centre at San Francisco and Les Halls underground complex in Paris are three most important underground facilities in the world where attempts have been made to provide fool proof safety. Fire alarms, systems for faster communication and movement of people out to safety have been provided. Smoke causes asphixion. Pressurised lift shafts are therefore made to keep the smoker away. Hydrants are installed to act automatically in case of fire. Specially trained staff are there in such buildings to handle any emergency till the outside help comes in People are also trained to evacuate themselves in an orderly manner in case of emergencies. Information on the subject are collected and exchanged to learn from the experience else where to improve fire safety in future.

Legal Aspects

Land, its ownership and the space lying below is a matter of debate. In many countries of the world, the owner of the land enjoys unlimited powers to use the assets down below, even the minerals. In many countries the state is the owner of all that lies below. This is mostly related to the minerals. International Tunnelling Association (ITA) got a detailed study done for the ownership issue and in the following paragraphs some information resulting from this study is given.

The ITA working group sent a questionnaire to 33 countries in 1987. The intention was to compare the legal aspects present in different countries and to assess the reasons for impeeding the growth of underground space development. The owner of a land has rights on the surface which is legally under his control. How for this control extends towards sky and underground down below is a difficult question to answer. British, French, German, Jewish and Roman laws as cited as early as 1250 recognise the rights of the owner to sky and the depths. The use of underground space by some one other than the owner, raises many questions that are to be sorted out before any underground space development can take place. The right of the owner must be protected or compensated to his satisfaction. Normally, the use of surface land is also done as

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planned to ensure for social and environmental concerns. The use of underground space is normally invisible form eyes, not much objection may arise but how for it is safe and to what extent it compromises the legitimate interest of its owner are to be examined in details. In many countries the regulation exist about the surface land use due to environmental and aesthetics but such regulations may not come in the way of underground development because nothing is seen on surface except the exits and entrances for underground facilities.

The underground facility may sometimes be under the control of a single surface right holder. In this case it is easy to negotiate and permit underground space construction. From the legal point of view, the underground space may lie below properties owned by many holders is different. In such cases the local authorities may limit the ownership right of surface rights holder up to a certain depth below which any construction may be permitted.

The legal issues are not very clear in case of underground space, hence there is need to develop conventions to permit and encourage the development of underground space.

National Tunnels for traffic are not many but there are some like Jawahar Tunnel across Banihal Pass in the state of Jammu & Kashmir which is the oldest. The twin tunnel system is 2.25 km long and the tunnels have a span of 5.2 m. Of late, there had been lot of traffic, hence the tunnel had been lighted and ventilated. It was constructed in mid fifties, hence needed some repair. That had already been done to enable the tunnel to take higher traffic volume. There are some short tunnels across Western Ghats on Pune – Mumbai express highway. A tunnel 8.5 km long across Rohtang Pass near Manali in Himachal Pradesh is under construction.

For urban traffic, there are no tunnels in any of the cities of India, except Shimla where some short tunnels are there. Many big cities badly need underground traffic by passes to ease the congestion. This mode of easing traffic flow may be necessary in the years to come. Underground car parking is being considered in Delhi and Kolkata. There are talks of mechanized underground car parks. All our the world there are only 3-5% of mechanized underground car parks. Such car parks are costly to operate. The assured power for operation may not be available due to general shortage of power in many cities. The drive in underground car parks may be possible in Delhi and Mumbai where there are good rocks suitable for underground construction and may not be expensive. In Delhi underground car parks can be constructed in Nehru Place, Karolbagh and Delhi university area. Traffic by pass tunnels may be considered in these and many other areas also.

The sub-surface belongs to the state hence the future underground space development may not be facing any legal hurdle. There may be a need to regulate the construction

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and use of the underground space in very thickly populated areas of mega cities of the country.

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CHAPTER - 3

PROBLEMS OF DELHI

Delhi, the home to 14 million people, many more join every day, is turning out to be a clumsy and unmanageable city. Unplanned development throws out of gear any planning efforts and hence Delhi had many master plans, failing to master the problems of Delhi. Any well meaning Delhi Master plan prepared with much efforts and care is thrown haywire, the very next day it is proposed. Probably this may go on as well as the efforts to make Delhi a livable city. Problems of traffic and water are at the centre stage and viable solutions for them are to be found out for improving the quality of the life of Delhi citizens. In the following paragraphs an attempt has been made to look into the Delhi, the home to 14 million people, many more join every day, is turning out to be a current status of the problems and what lessons can be learnt from it. This exercise may help in evolving solutions to the problems at hand.

Transport

Delhi has a total net work of 28,000km of road built and maintained by NDMC and MCD. These roads serve about 3.5 million vehicles as per year 2001 data. The number of vehicle will grow up to 6.0 million by the year 2021 (as reported in media), however the road length may increase by mere 7000km. The roads are therefore shrinking and as compared to 3 vehicles per km in 1972 the figure has come down to 0.001km per vehicle. This is predicted to be 0.0005km per vehicle by the year 2021. Fig. 3.1 give graphically the scenario on Delhi roads as reported by Hindustan Times, which is already a cause of great concern. The roads will get congested and people may take longer to drive through. The master plan 2021 allows mixed land use, multistoried buildings and regularization of 24 industrial estates. This may add to traffic woes and the blockages on roads may be more frequent in the years to come.

Fig. 3.1, Shrinking road space

In Delhi with 21% area for circulation, its citizens are faced with exhaust fumes creating environmental and health problems. One may say that the wider and important thorough fares may be better, but it is an illusion. Vikas marg carries 1.2 lacks vehicles and Ring Road 1.2 lacks vehicles every day during peak hours, adding to traffic snarls, air pollution and noise. The use of cars by Delhi citizen has increased tremendously. People are gradually prefering cars and every year 5-7% of cars are added. The two wheelers rise by 4% yearly and their owners are looking to buy old cars. The peak hour

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traffic has 40% cars and 35% two wheelers. On average a car carry 1.5 persons and two wheelers only 1.1. A car needs space which is three times of that of two wheelers. Progressively increasing car population is a serious cause of concern for shrinking roads.

The preference to use personal vehicle over the public transport is increasing. This is so due to lack of public transport system in the city. The travel within the city has increased. One used to travel about 6km per day in 1969 which has now doubled to 12 km. Use of bicycles has gone down to mere 10% from 30% about 20 years ago. The average per capita trip rate was 0.79km in 1993 will be 1.2 km by 2021. The average distance travelled was 11.23km in 1993 which may go up to 17.74km in the year 2021. The future portrayed is thus very gloomy for Delhi. People in the years to come may face serious traffic problems and some drastic solutions are needed to decongest the city roads. If this is not done, a Delhi citizen may be faster on foot rather than on wheels in Delhi as per Master Plan 2021.

Studies done by CRRI on 12 Delhi roads like Lala Lajpat Rai Marg, Lal Bahdur Shastri Marg, Vikas Marg, Najafgasrh Road, NH 24 by pass, Khel Gaon Marg, Arbindo Marg, Tula Ram Marg, have noted that during peak hours, the car figures go upto 50% of all types of vehicles on roads. The problems of these roads need to be studied in greater details to evolve solutions.

What is in the offing

The problems of near chocking roads of Delhi attracted the attention of the Govt. as well as the experts in the field of transport planning. The concept of peripheral express way is to divert the interstate traffic which passes through Delhi. Delhi is on route to interstate traffic. Lot of Delhi bound traffic is also there which has to reach the whole sale market situated within the congested city area. This traffic, when mingled with the traffic generated with in the city is also another cause of congestion and numerous accidents. It is at a conceptual stage now and may need to be studied for its feasibility. The peripheral express way will be passing through the National Capital Region. Such road may help in diverting the interstate traffic to some extent. Laying of these roads may need lot of land to be acquired. Construction may cost lot of money. How it can be done in foreseeable future is yet to be gone into?

The present ring road is proposed to be made an elevated corridor. This is being debated hotly these days, DMRC doubting about its viability. An elevated road may spoil the landscape in the vicinity of historical monuments and important building. Elevated roads and flyovers are very vulnerable to earthquake. Delhi is not earthquake safe and a threat of credible earthquake around 6 on Richter scale can not be ruled out. The Los Angles earthquake devastated multy level flyovers. The similar thing happened during Kobe earthquake resulted in collapse of elevated roads. The debris of these roads blocked the entire circulation space, causing great hindrance to rescue and relief operations. Elevated roads may therefore be liabilities in earthquake prone area like Delhi. Rebuilding or retro-fitting may be a difficult task as before any thing can be done,

52

the debris have got to be removed first. This may be difficult in view of all the approaches blocked by fallen remains of elevated structures.More and more fly overs seems to be the watch word for easing the transport problems in Delhi. These fly overs soon get inadequate with more cars joining in bumper to bumper vehicular movement during peak hours.

The traffic problems of Delhi may worsen in the years to come. The circulation space is shrinking. Widening of any road may be a big problem as there may not be any space for construction activities. These activities may interface with the on going traffic and activities of the people around. In view of the problem faced, the solution to traffic woes of Delhi are difficult to mitigate. Slower traffic with increasing car population slowing down further may force people to walk. Probably this mode may help them in reaching their destination faster. This may however be true for short distances. For long distances the roads or metro may be useful. People may therefore to bear with the problems at hand till such time some other viable alternative comes up.

Parking Problems

Car needs to be parked some where when not in use. The parking space has therefore to be available near the residence of the car owner and at the work place, commercial area, public places, transportation hubs and public utility establishments like hospitals, recreation centres, educational institutions and hotels. In Delhi, except at some commercial areas, parking lots are not there.

In the residential areas the cars are usually parked on roads and any space available for the purpose with in a planned residential complex. The parking space in residential areas is depleting fast due to increase in vehicle population. In many residential areas parking problems are acute and a cause for conflicts amongst the residents. The parking problem may therefore assume serious proportions in the years to come.

The parking in the commercial areas is either done off road or there are designated parking lots on vacant land. These parking lots are cramped and it is a difficult task to park a car or take it out during peak hours. Withdrawing a car after the closure of offices is a really tough job. All the approaches to the complex are full of honking cars vying with each other to pass through first. There are some below grade and multistoried parking lots also. They are usually not prefered as people find it convenient to park on the road side. Such off the road parking obstructs the traffic flow and may some times cause accidents or altercations amongst drivers.

Possible way out

Developed countries went in for underground solutions for their over ground problems. Many European and American cities have no flyovers at road intersections in the main city areas. Flyovers may be on free ways outside the city. Paris has several tunnel for traffic passing at road intersections. Such tunnelled underpasses have been considered

53

to preserve the beauty of the city and keeping the vision clear around historical buildings. The aesthetics is being forgotten in Delhi while constructing flyovers.

There may be traffic tunnels to ease the congestions in thickly populated areas. Many such possibilities can be explored in traffic hotspots where neither the space for construction of flyovers nor any scope for considering the road. Here the traffic moves very slow and the exhaust fumes add to pollution on roads. Vehicular pollution is a cause of increase in lung diseases and respiratory problems.

It is possible to short list road sections where tunnels can be built. In Delhi Aravali rocks are exposed on 6% of the area of NCT. Another 15% area has rock with in 30 metres of depth. Thus 21% area is mostly in south Delhi which has a very large vehicle population. Rock tunnelling is cheaper and tunnels may be very stable and can be used for several decades.

At many places in rock exposures or near by where underground parking lots are possible. In the developed countries major cities have underground car parks in commercial as well as residential areas. In the areas where there is rock, the underground car parks can be built very economically. It is possible to locate such places in commercial as well as residential areas where underground parking lots can be built.Going underground for transport infrastructure development is an important issue which needs developing the total package for the problems of a particular area. In the developed countries the congested areas of cities had been remodeled. The remolded areas have underground transport system and car parks adjacent to busy streets and commercial areas. Very convenient connections to city transport hubs can be provided, easing congestions and improving environment on surface by creating parks and gyms on the area free due to shifting facilities below ground.

The metro, even if fully developed, may not be in a position to wean away the Delhi motorized from his car , due to lack of parking facilities near metro stations. The park and ride concept may therefore be a distant dream without car parks near Metro stations. Underground space development must proceed through subsurface exploration, planning and designing underground space. Many legal, technological and societal problem may have to be sorted out.

Water

Introduction

Cities in the past have vanished without water. In the recorded history, Fatehpur Sikri was built by Akbar to be deserted soon for want of water. Tughlaka fort had the same history. The importance of water and its requirements for human survival was felt and efforts had been made to develop resources to feed the people. The distribution of water in Delhi is erratic, some areas are deluged while others crave for a drop. This diversity is not only peculiar to under developed areas but most prevalent in the most

54

developed areas, and Delhi is a living example of such a situation. It is feared that in future Delhi may face serious water problems due to not having its own source of water and growing water demands caused by fast and unplanned growth of population. The issue of water needs urgent attention, however, the issue had been debated time and again, specially before the onset of summer or the prospects of failure of monsoon.

Water scenario in Delhi

Delhi has a population of over 14 million and it is increasing at galloping speed with more migrating to Delhi and mostly setting in unauthorised colonies. The current consumptive need is 830 million gallons (MGD) per day. The DJB(Delhi Jal Board) supply is nearly 650 MGD within the network. The net availability is only 460 MGD which is barely 55% of the need. It is so due to leakage. The areas under Delhi Cantt, NMDC, Karolbagh, Civil lines and Rohini are well off. South and trans Yamuna areas face serious problems and have to worry about their future. Mehrauli, Narela, Najafgarh and Dwarka are the lowest water availability zones.

It is sometimes argued that Delhi has the highest per capita water consumption in the country. Probably, big cities in France, Germany and UK get less water as compared to the availability in Delhi. This may bolster the authorities dealing with water but may not help in putting it at back-burnes the burning problems of near water starved Delhi. People in Mehrauli get less then 60 litres per day, the lowest. South Delhi gets up to 140 litres per head and Central and Old Delhi citizens are in similar situations. Shahadara, a bit more comfortable with 160 litres per head. Rohini, NMDC and Contonment area get something between 175 to 400 litres per day.

By the year 2011 the water demand may grow to 1100 MGD and will ever increase at the accelerated pace. Citizens face a grin future. Some comment that future wars will be fought on water, but millions in Delhi are fighting daily battles to win water for the day.

How water is sourced

Yamuna is the life live of Delhi. It’s 2% length goes through Delhi, however, Delhi is the home to 20%population living on the entire length of Yamuna. Water through Yamuna Canal brings 225 MGD of water to Delhi which has to be drawn as per agreements with Haryana. 210 MGD falls in the share of Delhi which it can with draw directly. Ground water being pumped out contributes to 100 MGD and another 100 MGD is Ganga water which depends upon the will of U.P. In short only 55% of Delhi’s needs are met by sources which Delhi may claim to be its own.

The ground water, an important source of water is fast depleting and is a cause of great alarm. The ground water supplies about 130 MGD by the Delhi Jal Board (DJB). About 250 MGD of ground water is pumped out illegally by private tube wells operating all over Delhi, specially in south and south west Delhi. Officials of Central Ground Water Board

55

(CGWB) warn about serious decline in ground water level., Fig 3.2 depict gradual fall of water table since 1960. It has gone below 35 metres in South Delhi areas. Fig. 3.3 give area wise water table scenario.

Fig. 3.2, Progressive fall of Delhi ground water

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Fig 3.3, Water table in various Delhi areas

Search for solution

Water scenario is already grave and may continue to be so in the years to come. Scarce water to be shared by many is a difficult situation to cope up with. There may be a talk of enforcing laws to regulate water withdrawal from the sources, but its effectiveness is always in doubt. There may be tariff rise. Though legitimate, but it may give rise to theft. The real solution thus lies in developing indigenous source of water and firming up agreements with the neighbouring states for long term of water supply.Rain water harvesting is a good idea to pursue but there may be a condition. Rain water can be harvested only if there is rain. Irratic and insufficient monsoon behaviour may put all the efforts in jeopardy. Rain water harvesting will recharge the ground water which is going down very fast. Information available so for has proved that the harvested water definitely raises the ground water table. The technique is simple and a low cost effort. The idea is being encouraged and new construction can definitely adopt this technique in the areas where construction activities may be forth coming. Rain water harvesting can only be done on the roofs of ‘Pucca’ buildings. This technique may thus be limited to affluent areas and ‘Jhuggis’ may not get benefited. Jhuggis and unauthorised colonies have about 40% of Delhi population and these people may need some scheme managed by governmental efforts. How it can be possible is a matter to be considered in details? Delhi gets about 193 million cubic metres of precipitation which goes in to Yamuna every year. This is 193 trillion litres of water. For the year and on an average a Delhi citizen loses about 50 litres per day per head for want of water harvesting efforts.

57

Recycling of waste water is another idea which may find favour with policy planers. About 20% of Delhi’s water is used for flushing latrines in ‘pucca’ colonies. The water coming of industries is also huge which ultimately flows to Yamuna and contaminating it. Yamuna receives 80% of its pollutants from Delhi alone. The waste water flowing through drains can be treated and supplied for irrigation and washing. It may not be welcome for potable purposes. Recycling will not only solve water problem to some extent but also help in reducing the pollution of Yamuna. This treated water flowing beyond Delhi may be useful to the cities lying on its banks.

Getting water from the neighbouring states is also possible. Renuka Dam (Dadahu) in Himachal Pradesh has been considered an alternative. This dam is on Giri river, a tributary of Yamuna. Water stored in this dam will increase the availability of water in Yamuna and hence in supplying water to Delhi. The project is still on papers and when it will be pursued, is difficult to say. Delhi has a definite share of 300 cusses (162 MGD) of water from Tehri Dam Project which is nearing completion. This water will reach Delhi through the canal systems of Uttar Pradesh. Delhi will be at the tail end of this system. How much water will actually reach Delhi is to be treated at Sonia Vihar and will provide much needed water to South Delhi areas, which are gripped in great water scarcity these days.

The water scenario for Delhi is grim and in the absence of Delhi’s own source of water, the situation in future may be very difficult. It is therefore necessary to develop Delhi’s own source of water to avoid hardship to the people of Delhi.

Below ground solution

The transport and water are therefore two very serious problems of Delhi. It may be possible to evolve subsurface solutions to these problems.

In Delhi, there is a great scope for the development of underground space in view of the availability of good rocks of Aravali system. Underground traffic bypass, parking lots, storages and ducts for services may be possible in congested area to improve the quality of life. It is not possible to build all of them hence we may have to be selective. The water and the traffic problems are most critical hence need to be studied in details. The study has short listed scheme for storage of water underground, underground ring road and other road tunnels to ease traffic problems of the city. In the following paragraphs results of studies are being given briefly.

Underground storage of water

The National Capital Territory (NCT) has a population over 14 million and taking modest requirement of 200 liters per head per day, the need is around 2800 million liters per day, with a minimal growth of 5% per year, the requirement will be around 4200 million liters per day after 10 years. This may be rounded to 5000 million liters so as to absorb any imbalance. The needed space to store water is 5 million cubic meters per day and

58

the capacity for the year may be 1825 million cubic meters. It is possible to create so much of underground space in the rocks of Aravali system spreaded over 300 sq. km. in Delhi. In the north the Yamuna river enters Delhi and near Timarpur the rocks are closest to the river. Intake structure may be made here to divert the Yamuna flood water in to under ground main tunnel. This tunnel may end near Sarita Vihar and terminate in to a tail canal which may join Yamuna eventually. The main tunnel may have Board and Pillar (a criss- cross gallery system like chess board prevalent in coal mining) like structure on either side to store water. The galleries may extend laterally in the rocks down below. The galleries may be 5-7 metres in diameter and the entire system may be at least 50 m below the ground surface. The width of the galleries had been put at 5-7 meters so as to be self-supporting. It is possible to design optimum size after the realistic rock mass behaviour data is available. The storage may be in several levels below each other with at least a 10 meter thick parting in between.

At the intake side, there may be desilting arrangement. It should be designed to trap the silt and send it back to the river. The water may still contain some silt, which may ultimately settle on the floor of the galleries. Some arrangement or strategy has to be designed to clear this silt periodically. The withdrawal of water may be thought shafts located at predetermined places. These safts may also be useful for desilting and periodic maintenance of the system.

The entire scheme can be build in stages as per the needs and the availability of funds. The main infrastructure like intake structure, main tunnel, shafts and tail water arrangement can be constructed by the civic authorities. The lateral galleries can be constructed area wise and funded by the beneficiaries. A regulatory mechanism may have to be evolved to look after the construction operation and maintenance of the scheme.

Under Ground Road Tunnel

An underground ring road may be possible. It may be very long tunnel system, hence its viability and advisability has got to be evaluated very critically from the traffic and social acceptability point of view. Some short traffic tunnel by pass have also been considered like Nehru Place – Suraj Kund, Shakarpur-India Gate, Delhi University – Karol Bagh, Dhaula kuan, Cannaught Place and India Gate. Parking lots, an essential part of transport system can be made underground. It will help in solving acute parking problems in the city. Parking lots along Delhi metro stations may help in faster commuter traffic, which may help in park and ride mode of mass transport.

CHAPTER - 4

GEOLOGY OF DELHI

59

Introduction

The geological investigation show that the Delhi area, belongs to Alwar and Ajabgarh series of the Delhi System and it is structurally a complicated one. The Union territory of Delhi lies between latitudes 20º-20' and 28º-45' and longitudes 76º-5' and 77º-20'. Out of total 1484 square kilometers area 300 square kilometers are urban and 1184km are rural areas. Delhi is bounded in north and east by Indo-gangatic plains. In the west by the extension of the great Indian desert (Thar) and in the south by the Malwa plateau. The general trend of the ridge is N-S, which almost coincides with the strike of the rock.

It should be pointed out that no geological account is available in the geological literature except the general accounts given by Hacket (1881) and later modified by Heron (1917). Some studies had been done for metro alignment, but they are confined to limited areas. Ground water surveys have also helped in enriching the literature.

Geological setting

1. Quartzite2. Pegmatite (altered into clay)3. Schist

Quartzites and pegmatites belonging to Alwar series trend in the N-S direction and are found exposed in isolated exposures in the northern part of the area near Munirka. However, further south, near Masudpur, alluvium conceals the quartzites and such isolated exposures are rare.

Quartzite

Although the exposures are very less in number, the detailed structural mapping suggests that the quartzite occurs in the form of anticline and syncline with axial trend as N-S and SE-NW.

Quartzites are gray to bluish gray on fresh surface. But on weathering the colour varies from yellowish/ pinkish to reddish brown depending upon the extent of leaching of iron oxide. Weathering is generally pronounced along the joint planes and give rise to sub rounded blocks. At places, the rock is so much weathered that it has become friable and gives rise to a brown material locally known as ‘Bajri’ or ‘Morum’.

To the west of Jawahar Lal Nehru University, amygdaloidal appearance of quartzite is reported. The quartzite near Munirka shows pitted surfaces. Fig. 4.1 shows the location of rock exposure in and around Delhi.Pegmatite

Pegmatite bodies lie between Munirka in the north and Masudpur in the south. In all three pegmatite bodies could be mapped, two of them lie south west of Munirka and run

60

parallel to each other, whereas the third one lies south east of Masudpur village. They trend N-S and their trend coincided with host quartzite, lensoid shape measuring 1.25km to 1.5km in length and 200 metres to 250 metres in width. The thickest pegmatite vein is found near Masudpur and is about 250 metres in thickness.

Clay

Region between Munirka in north and Mahipalpur-Masudpur in the south forming an area of 7 square kilometers has been extensively quarried for clay that occurs within highly weathered zones of quartzites.

Fig. 4.1 Geological map of Delhi showing rock exposures(After Geological Survey of India)

Schist

The rock type occurs to the south-west of Munirka interlayered with quartzite in thin layers varying in thickness form 60cm to 100cm. Along the road cutting, it has acted like a lubricant during the process of gravity sliding.

61

BORE HOLE

951 701

682659

91562

0

1731

711

1688665770

931

8081498

461

462 1117

1878953

804

1256

1374

BORE HOLE

Schist bands are generally concealed on ground surface. Portion of schist and quartzites in Jawahar Lal Nehru University and Munirka areas is 15% and 85% respectively. In the pegmatite intrusion the proportion of mica schist and quartzites are 10% and 90% respectively but near Priya theatre the proportion of mica schist and quarzites varies between 30% to 70%.

Hydrogeological set up of Delhi

In Delhi the water table follows the topography of the area and lies generally at shallow depth in the alluvium and deep around the quartzite. It varies between 0.11m and 31.51m below the land surface and shows a drop of 0.5 to 1.0 metre in summer as compared with levels in winter. The fluctuation of water table normally reflects the seasonal distribution of rainfall in the region. The bedrock formations store water in cracks, crevices and bedding planes in the zone of saturation. The joints or cracks are numerous and inter communicative in the bedrocks. Ground water has played an important role in weathering of pegmatites exposed within host rocks of quartzite.

Highly jointed quartzites of Delhi system are intruded by pegmatites in the form of dykes along joints and shear zones. The quartzites on weathering have given rise to a friable zone (Badarpur gravels/ sands). The top layers of quartzites hold ground water under phreatic conditions and yield moderate discharge to open and bored wells. The Quaternary alluvium mainly comprises of clays, silts, sands and gravel in varying proportions and rest on the basement occurring at varying depths. These unconsolidated deposits hold ground water under phreatic conditions at shallow depth and probably under semi confined or confined conditions at deeper levels. Wells and tube wells dug within the alluvium yield moderate to good discharge.

A case record of seasonal fluctuation in the water table during June-November 1983 had been prepared. Water levels fluctuate seasonally a rise being caused mostly by recharge through precipitation during southwestern monsoon. In order to obtain the change in ground water storage between June and November 1983 (pre and post monsoon periods) the water levels for these months were compared. The comparison revealed that there is a rise in the water table ranging from +0.15m to +3.3m, the magnitude of rise increasing form east to west in general. A localised decline of up to –1.47m is seen around Moti Nagar located west of Delhi Ridge.

Similarly a case of net change in the water table form June 1978-83 needs mention. Besides the seasonal fluctuation in the water table, changes also occur from one year to another in response to the variation in the input and output factors. A study of the net change in the water table in five years period was made. During this period there has been a decline in the water table in almost the entire Union Territory except in a very small area in the southern most part of the Chattarpur basin where a rise of +1.89m has been recorded. The decline in water levels varies from –0.01m to –6.79m, the magnitude increasing from north east to south west in general. Only in the Chattarpur

62

basin, in the south, the trend is reversed ranging from a rise in the southwest to a maximum decline in the north east.

Hydrogeology

Water in soil and rock formations influences the rock/soil mass behaviour. The behaviour ultimately affects the subsurface construction. The Delhi area has four distinct physiographic units from the hydrogeology point of view. They are as follows.

Alluvial plain on eastern and western sides of the ridge (low to moderate yield prospects 25- 30 m³/ hr.)

Yamuna flood plain deposits (large yield prospects 50-100m³/hour) Isolated and nearly closed Chattarpur alluvial basin (low yield prospects 10-15

m³/hr.) NNE – SSW trending Quartzite Ridge (limited yield prospects 5-10 m³/hr.)

(a) Alluvial Deposits:

(i) Newer alluvium (Yamuna Sand) consists mainly clay/silt mixed with mica flakes to medium/ coarse sand and gravel. Newer alluvium, in general, is charecterised by absence of kankar.

(ii) Older alluvium is comprised of clay, silt and gravels. Older alluvium is predominantly clayey in nature.

(b)Hard Rock Formation:

The Alwar quartzites of Delhi System are hard, compact, highly jointed/ fractured and weathered. These occur with interbeds of mica –schists and gritty types that on weathering and subsequent disintegration give rise to coarse sand (Badarpur sands). Moreover, subsurface ridge also plays an important role in terms of acceptance of water in depleted aquifers and thus percolation of hard rock at depths. Subsurface ridge also plays important role in controlling the quality of ground water.

Ground water quality

Chemical quality of ground water in NCT Delhi varies with depth and space. In alluvial formations, the quality of ground water deteriorates with depth, which is variable in defferent areas. Brackish ground water mainly exists at shallow depths in northwest, west and southwest districts with minor patches in north and central districts. Ground water is fresh at all depths in the areas around the ridge in the central, New Delhi, south and south west districts. In the areas west of the ridge, in general, the thickness of fresh water aquifers decreases towards north-west. In the flood plains of Yamuna, fresh water aquifers exist down to 30-45 m . In other parts of NCT, Delhi areas falling under central, New Delhi, east and north-east districts ground water is fresh and potable at shallow depths excepts in a few pockets around Nizamuddin and Connaught Place where ground water is marginally brackish to saline.

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Depth to water levels

The Periodic monitoring of ground water levels indicates deeper water levels in the range of 20 to 45 m below ground level in southern parts of Delhi extending from Rajokri in the west to Kalkaji-Okhla industrial area including Chattarpur basin in the south. In the central part of south –west districts, water levels are in the range of 12 to 16 m below ground level. Shallow water levels within 5m are mainly in the flood plains of Yamuna falling in east and northeast within 5m below ground level are mainly in the flood plains of Yamuna falling in east and northeast districts. Most areas of north, central, New Delhi and northwest districts are having water levels in between 5 to 10 m below ground level.

Decline of water levels

A comparison of water levels from 1960 to 2001 shows that water levels in major part of Delhi steadily decline because of over-exploitation. During 1960, the ground water level was by and large within 4 to 5 meters and even in some parts water logged conditions existed. During 1960-2001, water levels have declined by 2-6m in most part of the alluvial areas. Decline of 8-20m has been recorded in south –west district and in south district the decline has been 8-30 m. Areas registering significant decline fall mainly in south and south – west districts and have been identified as priority areas for taking up artificial recharge to ground water by roof top rain water harvesting.

Rocks Along Metro Alignment

The alignment crosses the NNE-SSW trending Delhi ridge area between the Shadipur depot and Mandir Marg, a stretch for about 5km length. The eastern most rock exposures along the alignment are seen in the circular parts at the crossing of Rani Jhansi Marg and Panchkuin Marg, Barring a stretch of about 1km between Jhandewalan and Rajendra place stations, bedrock exposures are intermittently seen on both sides of the rock up to the crossing of Pusa Road and Shankar Road. Along Patel Road, the bed rock is exposed near the Patel Nagar road- over bridge across the railway line. The rock outcrops between Panchkuin Road and Patel Road are well exposed in Preet Vihar and Rajouri Garden area. The bed rock comprises grayish white coloured, fine medium and coarse grained quartzite having 0.25m to 1.5m thick interbeds of mica schists, pegmatite and quartz veins along and across the bedding joints, ranging in thickness upto 50cm are common. The quartzite are generally closely jointed and show staining and selective weathering along joints. On weathering of cementing material, the rock becomes friable and ‘Morum’ (variegated clay) pockets develop in highly weathered zones.

Joints along road alignment

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The attitude of bedding planes and principal joints sets as noticed in the rock exposures in the limited stretch of about 300m long are given below. The spacing of the bedding joints varies from 10 to 15cm.

Patel Road Area

The bedding strike N35ºE S35ºW and dips 35º to 50º towards south –easterly direction. Similarly the strike and dip of some major joints are noted down.

I. Strike: N10ºE S10ºW to N10ºW S10ºE Dip: 55º to 60º towards westerly direction

II Strike: N30ºE S30º W to N45ºE S45ºW

Dip: 15º to 40º towards north westerly direction.

III Strike: N50ºW S50ºE to N60ºW S60ºE

Dip: nearly vertical towards north-easterly directionIV Near horizontal joints

Shankar Road Area

The exposures in the area are moderately to highly weathered. The predominant bedding joints in the area strike N 5º E- S 5º W to N 35º E-S 35º W and the dip 35º to 65º towards south easterly direction. Other joint sets (major) in the area are:

I. Strike: N60ºW- S60ºE to N65ºW-S65ºE Dip: 75º steeply dipping towards north-easterly direction

II Strike: N25ºE-S25ºW to N35ºE – S35ºW

Dip: 70º to 75º towards north-westerly direction.

III Strike: N25ºE- S25ºW

Dip: 25º towards N 65º W

IV Near horizontal

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Table - Mechanical properties of quartzite in the ridge area of Delhi (After GSI)

Location Depth of rock below ground (m)

Types of rock

Porosity Crusing strength kg/cm²

Modulus of elasticity km/cm²*10 4

Karol Bagh to Mandir Marg

0.5-1.3 Quartzite with or without granite intrusion

0.69-1.42 310-421 0.96-6.7

Sidhartha Hotel to Rajendra Nagar

0.3-2.68 Quartzite with granite intrusion

Quartzite

Sandstone and quartzite with quartz piece

2.0-2.25

0.55-7.3

4.0-4.3

131-252

600-830

292-384

0.94-2.1

1.66

2.25-2.45

Palam area

Resistivity survey along the Palam – Gurgaon road revealed the depth of bedrock in the area is at 75 to 200m, except in the vicinity of exposures. The depth of bed rock is nearly 150m in the south of Palam and 110 to 130m near Gurgaon –Delhi boundry. The bed rock is overlain by sand, silt and kankar.

During the field season 1972-73, test surveys employing self potential, magnetic and resistivity survey techniques were conducted by GSI in Mahipalpur, Masudpur and Sikandarpur quarry areas in the south of Delhi to ascertain the contrast in physical parameters between the city zones and the host rock (Quartzite). The survey indicates clay occurrence within highly weathered zone of quartzite covering an area of 7 square kilometres.

With the presence of flaky minerals, few quartzites take up foliated appearance, particularly those collected from east of Mahipalpur.

During the field work conducted in the Mahipalur area, fresh to moderately exposures of quartzites were studied in the abandoned mines/ quarries and the following details of joints were collected.

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Table – I

Summary of joints in Quartzites in and around Delhi.

Joints Dip Dir/Dip Spacing

Conditions Persistency Remarks

Joint 1 115º/ 80º 30cm-200cm

Undulated altered, clayfilling, slightly rough surface, separation < 5cm

Continuous Bedding joints

Joint 2 5º/15º 30cm-100cm

Slightly weathered, and rough surface tight joint, no filling

Continuous Shearing along joints

Joint 3 20º/80º 30cm-100cm

Planner, rough to smooth, no filling separation >1mm

Discontinuous

Joint 4 288º/20º 6cm-20cm

Planner, rough, open intactuall, hard filling

Discontinuous

Well exposed at few locations

Mostly Joints were dry.

CHAPTER - 5

GEOTECHNICAL ASSESSMENT OF DELHI SUBSURFACE

Introduction

67

Working within and without the soil/ rock formations depend to a great extent on soil and rock mechanical characteristics of the ground to be dealt with. The soil/ rock response to any excavation activity disturbs the existing stress field and new state of stress may take shape. The new stress regime may or may not destabilize the excavated area. If the stress surpasses the rock/ soil mass in-situ strength, the process of failure may start. This can only be arrested by improving the rock mass behaviour or by installing appropriate support system. How soil/ rock mass may behave, what can be the extent of stress regime change and how it may affect the stress regime change and the over all stability of the excavated area, are some of the important questions to be answered before any underground construction is planned and designed. Delhi has two distinct geological formations, the alluvial plains of Yamuna and rocks of Aravali exposed in and around Delhi. Some information about the subsurface characteristics had been compiled from various sources. The reports of DMRC, GSI, Ground Water Board have been studied for this purpose. Alluvial Plains

These plains are part of Indo- Gangatic basin. Yamuna, is a perinial river and it has a gradient of 1 to 6000 from north to south in Delhi vicinity. The flood plains of the river have two categories known as older Alluvium and Newer Alluvium. The older alluviums lies below the newer alluviums are of Pleistocene age. They generally consist of inter-bedded, lenticular and interfering deposits of clay, silt and sand, ranging in size from fine to very coarse, with occasional gravely, “Kankar” which is generally hard, compact and irregular, occurs mixed with almost all their deposits. In the Shahadara block the older alluvium is sandy with clay in some proportions. In the Chattarpur area, the alluvium has been derived from the weathering of rocks and subsequent transportation and deposition.

Newer alluviums are of recent age and are confined to narrow and elongated flood plains of Yamuna. These deposits are mostly gray coloured sands containing minor properties of fines like silt, clay and fresh mica. These deposits have no kankar.

The ridge exposures are through the alluvial plains and the thickness of alluvial depends on the configuration of the ridge. The alluvial are the thinnest in the North Delhi area. The depth of alluviums is within 30 metres on the eastern side of the ridge and these deposits slope towards the river. Near Mall Road the depth of bed rock is 10 to 30 m. However, it suddenly increases to 100m on both the sides of Najafgarh drain. Near Sabzi –Mandi, Rani Jhansi road, Chandani chock and Sadar Bazar areas, the thickness of alluvium varies between of 0-20m, whereas it is 0 to 200 m near Rosanara Garden. Sudden changes in alluvium thickness may be due to faulting.

Alwar Quartzites

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Alwar quartzites are pre-cambrian rocks of Delhi system. They are mainly composed of quartzites with interbeds of schists and are intersected locally by pegmatites and quartzite veins. These quartzites are generally hard, compact, massive and jointed. After weathering they get converted to friable rock zones. The weathered pegmatites give rise to clay. The strike of quartzite varies from NE-SW to NNE-SSW and dip steeply towards east and south-east. Four sets of joints are prominent, namely bedding joints, dip joints, strike joints and diagonal or oblique joints. These joints form rectangle blocks of rock. Ferrogenous and gritty type of quartzites on weathering and subsequent distribution produce coarse sand and locally known as “Badarpur sand”.

Geotechical Assessment

Behaviour of soil and rock likely to be encountered while surface and subsurface excavations must be known reasonably accurate so as to design any structure below or over the surface. Mostly empirical approaches are used to assess the induced pressures due to excavation process. Behavioural characteristics of soils and rocks therefore be assessed as they are found in Delhi in different areas. The recent soils found in the flood plains of Yamuna and old alluviums are found close to the rock exposures and along various drains flowing through Delhi. In the following paragraphs attempts have been made to assess their behaviour with the help of prevailing rock mass classification approaches.

Alluvial Plains

They are mostly the flood plains called newer alluvium and older alluviums lies below these flood plains. These are of Pleistocene age where as newer alluviums are called recent.

Newer Alluviums

Yamuna Flood Plains

Flood plains of Yamuna constitute mainly of alternating layers of silty sand, sandy and clayey silt. These soil, close to Yamuna, show significant local variations in the soil gradation. This is probably due to shifting course of Yamuna over the centuries. It is not possible to classify all the riverbed alluviums in one group for assessment of behavioral characteristics but it is possible to have some typical values for specific sites. In the following paragraphs some values have been assessed and are given resulting from some subsurface exploration.

(i) Nizamuddin Bridge Area

Some studies had been done near Nizamuddin bridge along the railway line. In this area the soils consists of alternating layers of silty and sandy silt of about 13.0m depth. The individual layers are 1 to 3 m thick, gray fine sand with mica particles are found, popularly known as Yamuna sand. Soils below 13 meters are hard and dense silty and

69

sandy in nature, known as Delhi silt. N values vary between 7 and 36. At the surface N values are around 7 however they are upto 36 at a depth of 20 meters from the surface.

(ii) Madanpur Khadar

Soil in this area is loose, dark to brown sandy silt with low to moderate plastically. The N values near surface or around 5 and at a depth of 15m it is about 10.

(iii) Jasola

The soil have medium dense dark to brown sandy silt of low plasticity at shallow depth upto 5 metres. The N values were between 9 to 11. At higher depths, the soil was medium dense to dense, sometimes turning to very stiff brown clayey silt with gravels (traces). The N value increased from 49 to 66 for 10 to 15 metres of depths respectively.

Older Alluviums

These alluviums lie below newer alluviums. The products of the weathered rocks of ridge got mixed up with alluviums of Yamuna flood plains. These alluviums got deposited in situ or got transported to some distances before deposition. These alluviums may have better engineering characteristics. In the following paragraphs more information is provided, based upon the results of investigations done by drilling bore holes.

(i) Vasant Vihar

At shallow depth inorganic clay with stone clay had been observed. The N values were 36 in one location at a depth of 2.4 m

(ii) Pushpa Vihar

At Pushpa Vihar a bore hole was drilled up to a depth 15m. At shallow depth of upto 4m loose light brown sandy silt of low plasticity had been found out. The N values were between 18-28. From 8.25 to 12.45 m depths dense light brown sandy silt with traces of gravel were found. The N value varied between 34-51, however between the depth 12.45m to 15.0 the N value varied between 51-56 indicating better engineering behaviour

(iii) Mall Road

Loose light brown clay silt with gravel was found up to a depth of 5.55 m with N values between 3-9. At depths between 5.55m to 15.0m with N values between 3-7 were assessed. At depths between 5.55 to 15.0. medium dense to dense light brown sandy silt to silty fine sand had been found. The N values varied between16-31.

70

(iv) Kalibari – Mandir Marg

Yellowish grey sandy silt with calcareous kankars was found up to 3.45 meters and the N values were between 12-16, however there had been a patch of brownish grey sandy silt with kankars was found between 4.50 – 4.95m having N values between 11-33. The sandy silt found up to 3.45m reappeared with marginally improved N values of 14-22 between 10.50-15.45m depth.

(v) Tughlakabad

Medium dense light brown sandy silt with gravel of low plasticity was found up to 2.55m depth having N values of 13. Beyound 3.00 and up to 10.4 m stiff dark brown clayey silt with traces of gravel was found having N values between 11-20. (vi) Mehrauli

The area where the drill hole was drilled stood on fill material of loose sandy silt, loose boulders and gravels mixed with soil up to a depth of 2.5m to 10.30m. There was medium dense light brown sandy silt with traces of gravel. The N values varied between 16-29. Beyond 10.30 and up to 15.45m, there was dense light brown sandy silt with traces of gravels, having N values between 29-49.

(vii) Rohini

The area lies near Agra Canal. At a depth up to 2.55 m very loose dark brown silty fine sand having N value as 4 was found. Between 2.25 to 3.35m depth firm brown clayey silt, medium plastic was found with N values as 5. For another metre down below loose grey silty fine sand with mica particles was found with N value as 7. Between 6-11.55m medium dense grey fine sand with mica particles was found with N values between 12-26. Dense light brown sandy silt with traces of gravel was found between 14.25 to 18.45m depth with N values between 32-36.

(viii) Badarpur

From ground level to 1.5m clayey silt was found however it changed to silty loam between 1.50 to 4.25m with N values between 22-25. Between 4.25m to 5.50m sandy silt was found with N value was between 30-61.

(ix) Munirka Village

There was fill material on surface with silty sand, gravels and brick bats. Loose dense dark brown sandy silt with traces of gravel was found between 0.5 to 3.45m depth having N value varying between 5-11.

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(x) Chattarpur

Very loose light brown sandy silt and soil, dark brown clayey silt was found up to a depth of 1.95m, the N values being 3, however for 2.25 to 6.0m depth, firm dark brown clayey silt was found with N values 5-14.

(xi) Dhaula Kuan

Non- plastic sandy silt was found upto a depth of 16.55m having N values between 14-28. At depth between 18.15 to 29.85m sand silt and fine sand was found having N values between 32-65.(xii) Sultanpur Debas (Mangolpuri)

Sandy silt with N value as 11 was found between 1-2m depth, however sandy silt was found between 3-10m with N values between 11-28.

(xiii) Pusa

Sandy silt non-plastic in nature was found upto 6.15m with N values between 4-16. From 7.65 to 9.15m clayey sandy silt was found with N values varying between 11-12. Granular to medium sandy silt was found between 10.65 to 15.15m and the N values varied between 19-22.

The above details are tabulated in Table - I

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Table - I Typical Soil Charecteristics

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

1 1 Vasant Vihar 0-2.4m

Inorganic clay (CL) with stone clays 36 0.65 18 0.5

13128 770 Puspa Vihar 0-4

Loose light brown sandy silt, low plastic (ML) 7.0-8.0 0.65 6 0.1

13132 770 Puspa Vihar 4.0-8.25

Very stiff light brown clayey silt with traces of gravel, medium plastic (MI) 18-28 0.74 - 0.4

13139 770 Puspa Vihar 9.00-12.45

Dense light brown sandy silt with traces of gravel, low plastic (ML) 34-51 0.74-0.92 - 0.6

13141 770 Puspa Vihar13.50-15.00

Very dense light brown sandy silt with traces of gravel, low plastic (ML) 51-56 1.00 - 0.6

15861 951

Mall Road Near Teg Bhahdur Nagar 0-5.55

Loose light brown clay silt with gravel 3.0-9.0 0.0-0.70 - 0.1

73

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

15867 951

Mall Road Near Teg Bhahdur Nagar 5.55-9.45

Medium dense to dense light brown sandy silt 16-27 0.75 6 0.4

15868 951

Mall Road Near Teg Bhahdur Nagar 9.45-12.45

Medium dense to light brown silty fine sand 18-31 - - 0.4

15869 951

Mall Road Near Teg Bhahdur Nagar

13.50-15.00

Medium dense to light gray     - 0.4

11605 711KaliBari Mandir Marg 0.50 Filled up soil - - -  

11606 711KaliBari Mandir Marg 1.50-3.45

Yellowish grey sandy silts with kankars (calcareous nodules) of low plasticity (ML-CL) 12.0-16.0 3 7 0.2

11609 711KaliBari Mandir Marg 4.50-4.95

Brownish grey sandy silts with kankars of low plasticity (CL) 11.0-33.0 3.50-8.30 5.0-10.0 0.4

74

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

11615 711KaliBari Mandir Marg

10.50-15.45

Yellowish grey sandy silts with kankars (calcareous nodules) of low plasticity (ML-CL) 14-22 - - 0.3

13512 804 Tughlakabad 0.00-2.55

Medium dense light brown sandy silt with gravel, low plastic (CL) 13 0.67 - 0.2

13516 804 Tughlakabad 3.00-10.45

Stiff dark brown clayey silt with traces of gravel, medium plastic (MI) 11.0-20 0.80 5 0.2

15888 953 Jasola 0.50-2.55

Medium dense dark brown sandy silt, low plastic (CL) 11 0.61 - 0.2

15891 953 Jasola 3.00-3.45Loose light brown silty sand 9 - - 0.2

15892 953 Jasola 4.50-4.95

Medium dense light brown silty sand 10 - - 0.2

15893 953 Jasola 5.25-10.95

Medium dense to dense light brown sandy silt, low plastic (CL) 10.0-49.0 0.75-0.85 4.0-.05 0.6

75

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

15899 953 Jasola11.25-14.55

Very stiff brown clayey silt with traces of gravel, medium plastic (MI) 49.0-57.0 0.88-1.05 6 0.6

15903 953 Jasola14.55-15.00

Hard brown clayey silt with traces of gravel, medium plastic (MI) 66 - - 0.6

21118 1256 Madanpur Khadar 0.00-0.30

Loose dark brown sandy silt with clay, low plastic (ML) - - -  

21120 1256 Madanpur Khadar 1.77-2.55

Loose dark brown sandy silt with clay, medium plastic (MI)   - -  

21122 1256 Madanpur Khadar 3.00-15.45

Loose light grey fine sand with mica particles (SP-SM) 6.0-10.0 - - 0.1

25462 1498 Mehrauli 0.00-0.80

Fill: Very loose light brown sandy silt - - -  

76

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

25463 1498 Mehrauli 1.00-2.50

Fill: Very loose boulders and gravel intermixed with soil - - -  

25464 1498 Mehrauli 2.50-10.30

Medium dense light brown sandy silt with traces of gravel, low plastic (ML) 16.0-29.0 0.67-0.80 4 0.4

25473 1498 Mehrauli10.50-15.45

Dense light brown sandy silt with traces of gravel, low plastic (ML) 29.0-49.0 0.80-0.98 5.0-6.0  

31086 1731 Chanakyapuri 1.30 - - - -  

31087 1731 Chanakyapuri 2.19 - - - -  

31088 1731 Chanakyapuri 5.60 - - - -  

31089 1731 Chanakyapuri 6.62 - - - -  

31090 1731 Chanakyapuri 20.72 - - - -  

31091 1731 Chanakyapuri 25.70 - - - -  

32876 1878

Rohini {Agra Canal (Near Defence Sailing Club)} 0.00-2.55

Very loose dark brown silty fine sand (SM) 4 0.65 - 0.2

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SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfined compressive strength in kg/cm2

32879 1878

Rohini {Agra Canal (Near Defence Sailing Club)} 2.25-3.45

Firm dark brown clayey silt, medium plastic (MI) 5   - 0.2

32881 1878

Rohini {Agra Canal (Near Defence Sailing Club)} 4.50-5.55

Loose grey silty fine sand with mica particles (SM) 7 - - 0.2

32883 1878

Rohini {Agra Canal (Near Defence Sailing Club)} 6.00-6.45

Medium dense grey fine sand with mica particles (SP) 12 - - 0.1

32884 1878

Rohini {Agra Canal (Near Defence Sailing Club)} 7.50-11.55

Medium dense grey fine sand with mica particles (SP) 18.0-26.0 - - 0.4

32889 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

12.00-13.95

Dense grey fine sand with traces of gravel 30.0-36.0 - - 0.4

32891 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

14.25-17.55

Dens light brown sandy silt with traces of gravel, low plastic (CL) 32 0.90-97 5 0.4

78

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

32894 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

18.00-18.45

Dens light brown sandy silt with traces of gravel, low plastic (CL) 36 - - 0.4

32895 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

19.00-19.99

Very week light pinkish grey quartzite, very severely weathered disintegrated into gravel - - -  

19602 1164 Badarpur 0.00-1.50Clayey Silt (ML-CL) - - -  

19603 1164 Badarpur 1.50-4.25 Silty Loam (ML) 22.0-25.0 0.10 23.00-24.00 0.4

19608 1164 Badarpur 4.25-5.90 Sandy Silt (SM) 26 0.05 25.50 0.4

19611 1164 Badarpur 6.00-8.00

Poorly graded medium sand (SP) 30.0-61.0 0.00 29.50 0.5

13549 808 Munirka Village 0.00-0.50

Dark brown silty sand with gravel and brickbats - - -  

13550 808 Munirka Village 0.50-3.45

Loose dense dark brown sandy silt with traces of gravel, low plastic (CL) 5.0-11.0 0.70 5 0.2

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SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

18438 1117Cheman Farm Chattarpur 0.00-1.00

Very Loose light brown sandy silt, low plastic (ML) - - -  

18439 1117Cheman Farm Chattarpur 1.50-1.95

Soft dark brown clayey silt, medium plastic (MI) 3 - - 0.01

18440 1117Cheman Farm Chattarpur 2.25-6.00

Firm dark brown clayey silt, medium plastic (MI) 5.0-14.0- 0.70-0.75 12.0-13.0 0.2

11503 701 Madanpur Khadar 1.80-9.30Sandy Silt (Non Plastic ) ML 8.10-23.00 - - 0.4

11081 659Dhaula kuan Intersection 0.90-16.65

Sandy Silt (Non Plastic ) ML 14.00-27.63 - - 0.4

11093 659Dhaula kuan Intersection

18.15-29.85 ML-SM 32.18-65.18 - - 0.6

11147 665 Dhaula kuan 1.80-7.80Sandy Silt (Non Plastic ) ML 20.00-57.00 - - 0.6

6929 461Sultanpur Debas(Mangolpuri) 1.00-2.50 Sandy Silt 11 0.02 29 0.2

6933 461Sultanpur Debas(Mangolpuri) 3.00-10.00 Silty Sand 11.00-28.00 - - 0.3

80

SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

6943 462Sultanpur Debas(Mangolpuri) 1.00-2.50 Sandy Silt 8 0.01 28 0.1

6947 462Sultanpur Debas(Mangolpuri) 3.00-10.00 Silty Sand 8.00-25.00 - - 0.25

23191 1374Near Chungi Badarpur Border- 1.50-2.25 ML 9 0.09 30.0 0.2

23193 1374Near Chungi Badarpur Border- 3.00-5.25 ML-CL 10 0.12 28.0 0.2

23196 1374Near Chungi Badarpur Border- 6.00-15.00 ML 13.00-30.00 0.08 31.0-32.00 0.4

11341 688 P.M. House 0.90-5.40Sandy Silt (Low plastic) ML-CL 6.50-16.50 - - 0.2

11282 682 Raj Niwas 0.90-10.65Sandy Silt (Non Plastic ) ML 3.00-14.00 - - 0.15

10685 620 Pusa 0.90-6.15Sandy Silt (Non Plastic ) ML 4.20-16.00 - - 0.15

10690 620 Pusa 7.65-9.15

Clayey /Sandy silt (Medium Plastic) CL 11.60-12.40 - - 0.15

10692 620 Pusa10.65-15.15 GM/ML 22.40-19.50 - - 0.4

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SNo Borehole No LocationDepth in

m Soil Description SPT Value Cohesion(kg/cm2) Angle of Friction

Assessed unconfiend compressive strength in kg/cm2

   

Millinium Park- Jakir Hussain Marg 0-5.6

Fine sandy silt and silty fine sand       0.2

   

Millinium Park- Jakir Hussain Marg 5.6-10

Sandy silt fine sand and silty fine sand       0.3

   

Millinium Park- Jakir Hussain Marg 21-42.0

fine sand and silty sand, clayey silt, sandy silt       0.45

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Table –II Assessed Soil Mass Behaviour

Sl. No. Soil Type/ Place Depth SPT value Compressive strength kg/cm² (Assessed)

Cohesion kg/cm²(Observed)

1 Newer AlluviumMillinium Park

0-5m 10-19 0.20 0.10

5-10m 20-36 0.30 0.1510-20m 21-42 0.45 0.23

2 Jasola 0-5m 9-11 0.20 0.615-10m 10-49 0.20 0.75-0.8510-20m 66m 0.20 0.88-1.05

3 Older Alluvium,Puspa Vihar

0-5m 7-8 0.4 0.65

5-10m 18.30 0.6 0.7410-20m 34-50 0.6 1.0

4 Mehrauli 0-5m 16 0.40 0.675-10m 29 0.40 0.8010-20m 29-49 0.40 1.0

5 Rohini (Agra Canal)

0-5m 4-7 0.20 0.65

5-10m 12-26 0.40 -10-20m 18-36 0.40 0.97

6 Mall Road 0-5m 3-9 0.10 0.705-10m 16-27 0.40 0.7510-20m 18-31 0.40 -

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Table - III Rock Mass Characteristics

SNo Proj. No Borehole No Location Depth Rock Description Rock Type Rock Quality State of weathering Porosity

Crushing Strength in

kg/cm2

Compressive strength in

kg/cm2Point Load Strength RQD RMR Q

62 PRS222_3 915 Motiya Khan5.00-8.20

Quartzite rock with schist Veins

Quartzite rock with schist Veins - - 4 - 1020 - 60.00 68 3

1660 PRM12_16 1731 Chanakyapuri1.00-7.00

Moderately strong to strong grey quartzite, hard quartzite

Moderately strong to strong - -

167.00-488.00 - -

14.0-44.0 52 2

1676 PRM12_16 1731 Chanakyapuri7.00-14.0

Moderately strong light grey sandstone intermixed with mica particles, soft sandstone

Moderately strong - - - - - 0 15 0.8

1678 PRM12_16 1731 Chanakyapuri14.00-16.00

Weak to moderately strong reddish brown sandstone, severely weathered, soft sandstone

Weak to moderately strong severely weathered - - - - 0 15 0.8

1681 PRM12_16 1731 Chanakyapuri16.00-27.00

Moderately strong to strong light grey quartzite, hard quartzite

Moderately strong to strong - - - 355.20-414.9 16.00-18.00

16.00-20.00 52 2

1693 PRM12_16 1731 Chanakyapuri27.00-30.00

Very weak light grey sandstone intermixed with mica layer, soft sandstone Very weak - - - - - 0 15 0.8

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SNo Proj. No Borehole No Location Depth Rock Description Rock Type Rock Quality State of weathering Porosity

Crushing Strength in

kg/cm2

Compressive strength in

kg/cm2Point Load Strength RQD RMR Q

1839 PRM42_2 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

20.00-20.50

Very weak, light pinkish grey quartzite, very severely weathered, disintegrated into gravel quartzite Very weak

very severely weathered - - - - 0 15 0.8

1840 PRM42_2 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

20.50-22.00

Moderately weak light brownish grey quartzite, non-intact strongly discoloured, severely weathered quartzite

Moderately weak severely weathered - - - - 0 25 1

1842 PRM42_2 1878

Rohini {Agra Canal (Near Defence Sailing Club)}

23.50-30.00

Very weak light pinkish grey micaceous quartzite, medium grained very severely weathered, disintegrated into silty fine micaceous sand quartzite Very weak

very severely weathered - - - - 0 15 0.8

333 PRS203_4 808Munirka Village

4.40-4.60

Moderately strong dark grey quartzite, moderately to severely weathered quartzite

Moderately strong

moderately to severely weathered - - - - - 20 0.4

SNo Proj. No Borehole No Location Depth Rock Description Rock Type Rock Quality State of weathering Porosity

Crushing Strength in

kg/cm2

Compressive strength in

kg/cm2Point Load Strength RQD RMR Q

85

229 PRS228_2 931 Vasant Kunj0.00-3.45

Dense reddish brown coarse sand with mica particles ( Very severely weathered quartzite) quartzite -

very severely weathered - - - - - 30 1

235 PRS228_2 931 Vasant Kunj4.80-6.45

Very weak light brown quartzite, very severely weathered with mica particles quartzite Very weak

very severely weathered - 226.60 - 10.30 24.00 20 0.5

240 PRS228_2 931 Vasant Kunj7.50-50.0

Moderately strong light brown quartzite, severely weathered quartzite

Moderately strong severely weathered 0.043 316.50 - 6.80-10.30

24.00-26.00 30 1

86

Table - II gives the assessed soil mass behaviour parameters which may be used for designing.

Table –IV Rock Mass Parameters

S.No.

Site Q RMR Rock Pressure kg/cm² (Ult)

Cohesion internal kg/cm²

Angle of internal friction (Degrees)

Stand up time

1 Mahipalpur 1.66-8.00

50-68

0.3-0.85 0.2-0.30 25-35 1 week for 5m span

2 Nelson Mandela Marg

1.66-8.00

50-68

0.3-0.85 0.2-0.30 25-35 1 week for 5m span

3 Lado Sarai 0.87-9.0 57-77

0.32-1.39

0.2-0.30 25-35 1 week for 5m span

4 Chouri Bazar(10 m depth)

0.125 45-55

2.66 0.1-0.2 15-25 10 hrs for 2.5 m span

5 Chouri Bazar(20 m depth)

0.625 50-65

2.3 0.1-0.2 15-25 10 hrs for 2.5 m span

6 Patel Road Area

1.25 66 1.25 0.3-0.4 35-45 6 months for 8 m span

7 Shankar Road Area

1.04 65 1.27 0.3-0.4 35-45 6 months for 8 m span

8 Motiya Khan 5.0 68 1.5 0.2-0.3 25-35 1 week for 5m span

9 Chanakyapuri

0.75 15 0.3-1.4 0.1or less

15 30 minutes for 1m span

10 Chanakyapuri

2.0 52 0.3-.8 0.2-.3 25-35 1 week for 5m span

11 Rohini 0.75 15 0.3-.8 0.1 or less

15 30minute for 1m span

12 Rohini 1.0 25 1.27 0.1-0.20. 15-25 10 hrs for 2.5m span

13 Munirka 1.0 30 1.27 0.1-0.20. 15-25 10 hrs for 2.5m span

14 Munirka 0.40 20 1.33 0.1 or less

15 30 minutes for 1m span

Aravali Rocks

The ridge exposures in Delhi are the extensions of Aravali. The rocks are generally metamorphic in nature with patches of sedimentary rocks and igneous intrusions. Many holes had been drilled to study the sub-surface characteristics of rocks and the data obtained through these bore holes in some areas haves been analysed to assess rock mass behaviour using rock mass classification approaches. The Rock Mass Rating(RMR) of Bienniawaski and Rock Mass Quality(Q) proposed by Barton have been assessed as they are the two most used approaches. The data is very scanty and does not possess all the

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parameters needed for applying rock mass classification approaches. The missing data had been judiciously assumed. In the following paragraphs details for some areas are given.

(i) Motiya Khan

Quartzites with schist veins are found in the borehole up to a depth of 8.20m. The rock material has a compressive strength of 1020 kg/cm². The assessed RQD 60, RMR is 68 and the Q value is 3.0. The rocks lie below soil and weathered rock cover of about 5m in thickness.

(ii) Chanakyapuri

Moderately strong to strong gray quartzite are exposed on surface and upto a depth of 7m. The compressive strength of rock material is 167 to 488 kg/cm². Assessed RQD is 14-44, RMR is 52 and the Q works out to 2.0. From 7m to 14m moderately strong light to gray sandstone intermixed with mica particles are observed. The assessed RQD is negligible, however RMR is 15 and the Q works out to 0.75. Further down from 14 to16m, weak to moderately strong reddish brown sandstone, severely weathered and soft is found. The RQD is therefore zero, RMR being 15 and Q as 0.75. Between 16 to 27m, moderately strong to light gray hard quartzite reappears. This rock has RQD as 16-20, RMR as 52 and Q as 2.0. The weak sandstone reappears between 27-30m. The RQD is zero however RMR and Q are 15 and 0.75 respectively.

(iii) Rohini, Agra Canal (Near Defence Sailing club)

Very weak, light pinkish gray quartzite, very severely weathered, disintegrated into gravel is found between 20-20.5m. The assessed RQD is zero, RMR is 15 and Q works out to 0.75. Between 20.50 to 22.0m, moderately weak light discoloured severely weathered quartzite is found. It has practically no core recovery hence RQD is zero. The assessed RMR and Q are 25 and 1.0 respectively.

(iv) Munirka village

The rock is moderately strong dark grey quartzite, moderately to severely weathered, found at a depth of 4.0m. No core recovery, hence the RQD is zero. The assessed RMR is 20 and the Q is 0.40.

(v) Vasant Kunj

The rock exposed at surface and upto 2.45m is dense reddish brown coarse sand with mica particles and severely weathered quartzite. There had been no core recovery, hence the RQD is zero. The assessed RMR and Q are 30 and 1.0

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respectively. Further down between 4.80 to 6.45m, very strongly weathered, light brown quartzite is found. The rock material has a compressive strength of 226 kg/cm². The RQD is 24 and assessed RMR and Q are 20 and 0.50 respectively. Drilling beyond and up to 50m passed through moderately strong light brown quartzite (severely weathered). The rock material has a compressive strength of 316.50 kg/cm². The RQD was 24-25 and the assessed RMR and Q were 30 and 1.0 respectively.

The informations through drill holes are for only a few places. The data is therefore insufficient y and may be regarded as scanty. Table –III give the data for ready reference. Table - IV summarises the above data that may be used for designing. The table also includes the data reported in earlier reports. For assessing Q, RQD has been assumed between 5-10 in case the RQD value is zero. This is a normal practice.

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CHAPTER - 6

TRANSPORT UNDERGROUND

Introduction

Transport infrastructure of Delhi include road, flyovers and underpasses, beside parking lots, at many places get outdated due to very fast growth in vehicle population. The unplanned growth of the city and multiplicity of modes of transport on the roads of Delhi is a unique problem. The situation causes accidents and slows down the traffic. The under ground transport system may help in segregating traffic, providing easy way out from congested areas by providing under passes and underground roads at locations where no other solution can work in view of lack of space for roads. The metro system is under development that may cater to the need of commuter but goods transport with in and without the city cannot be helped. Every third Delhi citizen, having a motorized transport may find it difficult to switch over to metro in the near future due to lack of parking at appropriate places. The city is therefore ripe for considering an underground network of roads. In the developed countries many cities have traffic by passes, ring roads and underground parking lots. In Delhi, there are good possibilities in view of Aravali rocks and not so poor alluvials of Yamuna banks as well as at other places.

The Possibilities

It is a well known fact that four wheelers constitute up to 45% during peak traffic hours. The four wheeler population is growing at a faster rate and one can imagine the problem when Tata’s small car model comes on road in the near future. The underground road net work may help to a great extent the four wheeler traffic. Some of the underground roads may be as follows.

(1) Underground ring road(2) Tunnelled road from Nehru Place to Faridabad(3) Underground road from Laxmi Nagar to Connaught Place.(4) Underground road from Pandav Nagar to India Gate.(5) From Dhaula Kuan to Cannaught Place(6) From Dhaula Kuan to India Gate(7) Delhi University to Shankar Road

The above are some examples and most of them are more than 5km long. There may be shorter tunnel roads to provide faster movement of traffic in other areas also where there may not be space available for widening the roads or making flyovers. Fig. 6.1 give locations of the above mentioned tunnels roads. These alignments are yet to be refined in view of the traffic density and the site constraints for tunnels construction. In the following paragraphs some more details are given about these tunnel roads.

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Fig. 6.1, Proposed tunnel routes

Underground Ring Road

The ring road like at Stockholm may not be fully underground. The tunnelled portions may be in the area where space of for widening road may not be available. The ring road is given in Fig.6.1. The tunnelled portion may start as a submerged bridge flanked by concrete conduits in the Yamuna bed from near Jamia Millia to Udyoug Marg in Noida. It may pass through Nehru Place, IIT, R.K.Puram, Dhaula Kuan, Karol Bagh, Patel Nagar, ISBT and thereafter through a submerged bridge in Yamuna bed to Shahadra. The tunnelled portion may be at least 20 metres below the surface to avoid complications during construction. This may need a ramp of at least 500 metres length. The Yamuna river bed submerged bridge may provide enough space for the ramp with in the bridge and the concrete conduit system. There may be entries and exits at convenient places, like Sukhdev Vihar, Nehru Place, IIT/ Karol Bagh, R.K.Puram, Patel Nagar, Delhi University and any other convenient place. The given alignment is only general in nature and it has to be firmed up by data about traffic requirements and construction constraints at entries and exit points. About half of the alignement passes through Aravali rocks that can easily be bored through by tunnel boring machines. The ring road will be in twin tunnels having an underground length of 30 kms.

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Nehru Place to Faridabad (Surajkund)

The Nehru Place area attracts huge car traffic and most of it goes to Faridabad where there are many residential colonies around Surajkund. The current road system with fly overs fails to cope up with the rush hours and is a real bottle neck. In this area the rocks are exposed and these rocks are extended up to Surajkund. It is possible to construct tunnels through rocks. Optimum rock cover may also be available as the rock exposures are fairly above the ground. The tunnels may also have direct access to underground parking lots in the Nehru Place area. A visitor friendly walkways can also be constructed underground to approach various buildings and will mostly be under rock exposure. This tunnel may be 7km long.

Laxmi Nagar to Cannaught Place

The traffic tunnels start from Laxmi Nagar commercial complex and may end near Connaught Place. The Yamuna be crossed by submerged bridge near ITO. The tunnels will be done through soils and Yamuna sands. There may be difficulty in finding space for ramps near to Connaught Place. Many design and site problems may come up which can be over come by modern technology. The route carries very heavy car traffic during peak hours and will be very helpful in speeding up the car traffic to Connaught Place. The tunnel system may be around 5 km long.

Pandav Nagar to India Gate

The tunnels may start near Yamuna river beds. It will follow the route of existing Pontoon bridge. The route will be connected to a submerged bridge and pass under the area close to power station, Pragati Maidan and National Stadium. It may be possible to find space for exit ramps in the area adjoining National Stadium and India Gate. The tunnels will pass through soils and Yamana bed sands. The submerged bridge under Yamuna bed will provide conduits for tunnels. The twin tunnel system will have a length of about 7 km.

Dhaula Kuan to Connaught place

The tunnel system will start near the bus terminal and end close to Connaught Place. The tunnelling media will be rock as well as soils. The route will be Budha Jayanti Park, near the Presidential Estate, below Rajpath and will end near Janpath. The tunnel will be 6 km long and may carry the car traffic to Cannaught Place and India Centre. There may be exit and entries at India Gate at suitable places. The system will be 6 km long and will provide faster traffic between these two points.

Dhaula Kuan to India Gate

There may be difficulties in providing exit and entry for Dhaula Kuan, Connaught Place route, hence a separate link may be needed between Dhaula Kuan and

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India Cetre. The route will pass through Budha Jayanti Park, near Presidential Estate and may terminate on the outer periphery of C. Haxagon. There are rocks in most areas as well as soils tunnelling through them may not be difficult, however there may be problems in locating exits and entry points. The system may be 6km long.

Delhi University to Shankar Road

Approach to Delhi University from Karol Bagh is through very congested roads. The connectivity will be lot more easier through tunnels. The subsurface route will pass through Subzi Mandi, Civil Lines and Kingsway Camp. In these areas good rocks are exposed or lie very near to the surface. There may not be difficulties in locating entry and exit ramps in view of good rocks and space around these points. The tunnel system will be 7 km long.

The above routes proposed are only indicative. Their lay out is to be finalized after undertaking extensive traffic studies. The result of traffic studies will help in refining the alignments. More tunnels alignments can be proposed depending upon the traffic needs.

Entries and Exits

These are usually through ramps. The tunnels are supposed to be below ground and are to be done by tunnel boring machines, the level portion of the tunnels should be at least 20 metres below ground. This depth will eliminate the possibilities of tunnels running into services lying below ground. The cover of 20 meter would be sufficient for single lane (5.5 metre tunnels) however for two lane tunnels (7.5 media) the cover has to be 25 metres. Assuming a gradient of 3% ramps in the range of 600-800 m may be needed. These ramps may begin at the surface and dip down. Most of the length of the ramps may be dug by cut and cover method necessitating shifting of services and relaying them after construction.

For the ramps there has to be sufficient surface space available to facilitate construction. There has to be proper planning of the ramps. Their locations may dictate the method of construction as well as traffic management adopted during construction period.

Emphasis on Underground

The road network may be on elevated carriage way or in tunnels. The tunnels may either be close to surface constructed by cut and cover method or deep below populated areas by normally tunnelling method. Elevated and cut and cover mode require relocating the services and need sufficient right of way for construction. These require land acquisition for relocating services. The affected citizens resist them. The alternatives consequently cost lot of money. By going underground the problems of services and land acquisition are substantially minimized and are normally confined to the ramps only.

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The underground tunnelling may be preferred as there may not be many obstacles to be negotiated and the alignments can be kept as straight as possible. Theoretically, underground working provides lot of planning and designing freedom because it is not influenced by any obstacle coming on way in case of elevated or cut and cover method. The activities on surface go usually and the tunnel construction continues uninterrupted down below.

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CHAPTER - 7

STORAGE OF WATER UNDERGROUND

Introduction

Water woes of Delhi are well known. They are likely to grow in future due to population growth, lack of own resources, faster depletion of what ever is available and reluctance of neighboring states to help. Water for Delhi will therefore be a very important issue. There is thus an urgent need to explore the possibilities of developing Delhi’s own sources of water. Underground storage of floodwater of Yamuna is one of the possibilities. Delhi is endowed with good rock formations of Aravalis and they spread over 300 sq km of Delhi’s sub-surface. These rocks may provide good sites for developing an underground water storage system. In the following paragraphs this possibility is being discussed in details.

The storage concept

Yamuna floods occur every year and the water sometimes inundates the low laying area and the water ultimately flows away from Delhi. If the water is impounded below ground it can be very useful. The low laying areas may suffer less flood damage and the stored water can help in developing Delhi’s own water resources, besides enriching the ground water.

The Yamuna enters Delhi from north and leaves it down south. The Aravali rocks are very close to Yamuna near Majnu Ka Tila. The rocks are near university area and in Karol Bagh, R.K.Puram, Vasant Vihar, Nehru Place. They again come closer to Yamuna near Tughlakabad in the vicinity of Sarita Vihar. The rock stretch is about 25 km long and has a maximum width of 15 km. The rock spread is large enough to accommodate a network of underground galleries that may hold water. The intake arrangement may have a stilling basin close to the Yamuna bank near Majnu Ka Tila. This stilling basin can be designed to permit relatively cleaner water in to the intake tunnels. These intake tunnels may be 5 to 7 m diameter and may run parallel to each other and may diverge laterally to follow the spread of the rock formations down below. These tunnels may converge near Tughlakabad to ultimately form in to a tail structure to join Yamuna again. From these intake tunnels, the network of galleries will spread in lateral as well as longitudinal direction. These galleries will also be predominantly in rock formations. Fig. 7.1 show a schematic arrangement of the underground system. Fig. 7.2 shows a small section of the network of storage galleries.

There may be many shafts through out the network of the galleries from where the net work can be approached during construction and after construction these shafts can help in withdrawing water. The entire plan of the system has got to be

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made after very thorough study of the area, the sub-surface scenario and the surface features.

The intake and tail structures may have to be made as a common facility, however the network of galleries can be developed as and when needed. In the intake tunnels there may be provisions for taking out the ports for network of galleries. It is not necessary, therefore to develop the entire system in a single operation. The common facility may therefore have to be developed and owned by a government agency, however, the network of galleries may be developed and owned by the beneficiaries.

Stilling Basin

It will be a structure built parallel to the riverbank from where the water will enter the system. The arrangement is to be reasonably large to work as a stilling water pond where the sediments may settle and can be flushed back to the river from time to time. The wall of this structure towards the riverfront should be strong and high enough to withstand the water pressures during high floods. The entry of floodwater has to be through appropriately designed hydraulic gates and entry arrangement. The stilling basin has got to be designed on the basis of hydrological and geo- mechanics constraints prevailing at the site.

Intake Structure

At the end of the stilling basin there will be a gated entry structure for water to flow in the main tunnels. The main tunnels will have to be designed in such a way to lessen the turbulent water flow. The deepest point in the tunnels system may be about 50 metres below the surface. This depth has to be negotiated by the tunnels being driven with gradual inclination to avoid built up of water pressure during water filling. The design of the intake structure will be similar to one adopted for a hydroelectric power tunnel’s intake structure. During the filling up operation lot of trapped air may cause huge pressure built up which may cause failure. There has therefore to be a suitable arrangement of de-airation of the water entering the tunnel system.

The Main Tunnels

The main tunnels may be 7 to 10 m diameter. There has to be a gap of at least 20 metres between two parallel tunnels. There may be four or more tunnels. They may be so aligned as to reach the areas where the storage galleries may have to be built. These tunnels will be lined and may be either circular or U-shaped.

The Tail Structure

The main tunnels may converge near the tail structure to connect the system to the river. The excess water and sludge etc. will flow into the river. The structure will have gates to regulate the flow of water. The gates will also prevent the

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reverse flow of water of Yamuna during high floods. This arrangement will again be like tail race arrangement of a hydroelectric project where the tail water rejoins the river.

The Storage Galleries

These galleries may be 5 to 7 m in diameter and will mostly be unlined in areas where they have been driven through rocks. In the weak zones the galleries may have to be appropriately supported. The preference has to be the galleries being driven in rocks. These galleries may be excavated in the form of a network as per the water needs of the area for which they may provide water. These galleries may be about 50 m below the surface and may be reasonably stable in good rock formations. The area wise network of the galleries will have to be connected to the main tunnels through a suitable arrangement. This arrangement has to be provided with a gate through a shaft so that it can be operated from surface to regulate the supply of water to the individual network of galleries.

The two galleries will have a separation of 10-12 m of rock in view of stability. The total volume of these galleries may be between 400-600 billion litres of water. The volume of water may assure a supply of 80 liters per head of the water per day. Another floor of galleries can be excavated about 10 meters above to double the volume of water storage.

Fig. 7.1, General Plan of water storage system

Tail Structure

Main Tunnel System

Intake Structure

Storage space (within solid lines)

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Shafts

There may be about 100-150 shafts driven to reach to the gallery network. The diameter of these shafts may be 6m and will be lined appropriately. These shafts will be driven with the construction of the common facilities. They will be used for the construction of gallery network and the main tunnels. During the operations they may provide links for water pumping, maintenance, installation and operations of various gates and ventilation

They are to be located in suitable places where space may be available and may be at safe and secure places during construction and operations.

Water Extraction

The underground storage will be extended over 300 sq km, mostly in rocky areas where very meager ground water is available. Some of the rocky areas are the worst affected by water scarcity. The needed water can be pumped out by pumps installed in shafts. At convenient places the pumped out water can be treated and supplied to the users.

Currently the raw water is drawn either from the river, canals or pumped out from underground. This water is treated in treatment plant and the water is dispensed to consumers through long water mains. These mains pass through congested areas, sometimes are breached, wasting lot of water. Water moving through long mains loses much of pressure and low water pressure prevents the supply of water at higher elevation flats.

In the proposed scheme the water can be pumped out from many places within the area of the storage network and be supplied after treatment in smaller treatment plants. The lengths of mains may be smaller. Probably this may help in better water distribution, avoiding losses of head as well as water.

Water Seepage

As already mentioned, most of the storage galleries are unlined. The stored water may seep. This seepage water may help in augmenting the ground water around the storage area. The seepage will reduce gradually as the floodwater may bring lot of particulate matter. This particulate matter may clog the rock joints that help in reducing seepage. Thus after a few years of storage operation there will not be any seepage and the stored water may not suffer any further loss.

Silting of Storage

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The floodwaters carry huge silt. This silt entering into the storage galleries may remain there and in the due course of time the entire area may get silted up. The silt percentages in the Yamuna water during rainy season are below one of percent. The complete silting may therefore be over with in one hundred years. The silted up area so formed by deposition may still contain lot of water. It may be that even after 100 years, the galleries may have up to 50% voids that may store water. The silted area may therefore be converted to aquifer that may have a longer life. In all probabilities, the storage may serve for about 50 year most efficiently.

How Much Cost

There are no references in literature about such storages ever built any where in the world. This may not be a deterrent to discredit the new idea. Any guesswork about the cost may be difficult under such circumstances. It is a well known fact that larger the volume of underground construction, lesser is the cost. The facility can be built over a period of time and as per the needs of a particular area. The beneficiaries can contribute for its construction. A detailed techno-economic study has got to be done to adopt the idea for implementation.

Advantages and Disadvantages

Under ground storage for water may have the following advantages,

(1) A step forward towards water self sufficiency in Delhi.(2) Shortening the length of water supply mains there by reducing leakages and

loss of head.(3) Helping in reducing the damages during floods as a major part of floodwater

can be diverted to the under ground storage system.(4) Help in re-charging the ground water.(5) Ground water recharging may help in the growth of greenery on rocky areas.(6) Can be used for supply of drinking water.

Disadvantages

(1) Underground space area developed cannot be dismantled easily.(2) It is a costly proposition.(3) Can be an easy target for vandalism and terrorist attack.

The scheme is general in nature and to implement it in reality will involve lot of surface and sub-surface investigations. A very carefully thought planning and designing has got to be done, as it may be the first of its kind of work in the world.

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CHAPTER - 8

PLANNING AND DESIGN

Introduction

Underground space development depends to a great extent on the availability of realistic data about the behavioural characteristics of the tunnelling media ie soil/ rock. The data can be obtained with the help of planned subsurface investigations. For planning also the data is needed to locate a particular component, its basic dimensions and its interface with the interconnected structures. The underground space planning and development is not affected by any surface features as is a usual case with the surface structures. The planner has a lot more freedom to plan, provided the sub-surface media is component enough to sustain the construction.

Planning

The proposed tunnels roads and galleries for water storage will be extended over large areas. In a city that is already very congested, there may be many problems for locating any structure.

The entry/ exit ramps for roads and shafts for water storage have to be located in areas where the land may be available for the purpose. The following paragraphs give about the planning aspect.

Tunnel Roads

Fig. 6.1 gives the general layout of the roads. All roads will have numerous entry and exit ramps. Most of these will be 600 to 800 meter long and may have to be built by cut and cover technique. In the following paragraphs some information is given on the planning.

(1) Ring Road

It will be the longest tunnel system having a couple of submerged tunnels for Yamuna crossing. These are to be sited as per the geo-engineering advantages and traffic density. For the siting of submerged bridge the following points are worth considering.

(i) The length of the river crossing to be the most minimum(ii) The sub-soil characteristics should be better to sustain the load of structures

or may need lesser treatment for strengthening.(iii) The location of the submerged bridge should be nearer to high density traffic

areas.(iv)The entry and exit ramps may have to be located in places where space may

be available for the construction of ramps.

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The following places are suggested for submerged bridges

(1) Jamia Millia(2) Pandav Nagar – Ring Road Pontoon bridge(3) Shakarpur – ITO(4) Near old railway bridge

These alignments are across the river and there is enough space available for the construction of ramps.

Places for exit/ entry ramps

Rock out crops are to be preferred over alluvials in view of better characteristics. There has to be space available for locating the ramps. Following are some of the locations worth considering.

(1) Nehru Place(2) R.K.Puram(3) Budha –Jayanti Park(4) Karol Bagh(5) Delhi University

The following paragraphs give more details of different roads.

Nehru Place – Faridabad

The rock exposures near Kailash Hill, just behind Nehru Place is the ideal place for locating the entry and exits. There is enough space available and good rocks for construction. At the other end the Suraj Kund area has lot of space and rocks below to facilitate construction.

Laxmi Nagar-Connaught Place

Laxmi-Nagar commercial area, though very congested already can be considered for ramps. Appropriate technology has got to be adopted for construction that may cause least disturbance to the surface buildings and activities. Again the Connaught Place area is highly built up and appropriate technologies may have to be adopted to construct the ramps. The experience available with DMRC may be very useful.

Pandav Nagar to India Gate

The Yamuna bed may have sufficient space to accommodate ramps and submerged bridge. The areas near National Stadium may have to be temporarily used for construction of ramps by cut and cover method. Special technologies may have to be adopted.

Dhaula Kuan to Connought Place/ India Gate

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In the Dhaula Kuan areas there is lot of open space that may provide space for ramps. Most of the areas are in green belt but can be used temporarily for the construction of ramp. After the construction the area can be restored back. In the Connought Place area ramps can be constructed by special techniques to avoid any disturbance to the built up area. At India Gate the space may be there but appropriate technique may be needed for construction to avoid any inconvenience on surface and the heritage buildings.

Delhi University - Karolbagh

Both the places have rock exposures and vacant land around. There may not be much of difficulties in locating entry/ exit ramps in the area.

In the foregone paragraphs the locations had been discussed in general. It will be necessary to undertake detailed surveys at the locations for fixing a most suitable alignment. In the congested areas there are numerous services installed in ducts below ground. These services may have to be shifted. A detailed survey of these services has got to be made. The shifting and restoration plans have got to be worked out. The services may therefore be an important part of planning of the alignments.

Dimensions of Tunnels

The road and water tunnels are to be driven at different depths. The road tunnels are to be closer to surface in view of desired lower gradients, but for the tunnelling there has to be a minimum cover equivalent to double the span of the tunnel to be constructed. For single lane the span may be six meters, however it may be nine meters for double lane traffic. The depth may therefore be between 20 metres 25 metres respectively. This depth may provide trouble free tunnel construction as there may not be any obstacle on way due to underground service facilities. This may however pose problem at portals and ramps and the services may have to be relocated to facilitate construction. Road tunnels may need span of 6 and 9 metres.

In case of water tunnels, there are two types of tunnels, one larger tunnels, 7-10 metres which will be main tunnels running between the intake and tail end. The other tunnel for storage net work may be 5-7 m diameter. All these tunnels will be at a depth of 50m except the sections near the intake and tail ends. The storage network made at shallow depth may interfere with the future subsurface development hence there should be at least 30m of rock thickness available in between for any other underground structure.

The Tunnelling Media

The road tunnels will be driven through soil, weathered rocks at different stages of disintegration and fresh rocks. In most part of Delhi the water table is within 20

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metres except in some rocky area. The below ground water table working is difficult but can be made easier with the help of new techniques and machines.

Water tunnels will be mostly through fresh rock formations except at places where there may be weak rock zones. Usually the rocky formations are dry but some ground water is available in fractured rocks.

Behaviour of Tunnelling Media

Chapter 5 has dealt extensively with the probable behaviour of subsurface formations. The newer alluviums are a bit less compact and consolidated as compared to older alluviums. The highly weathered and disintegrated rocks may also behave like alluviums. Alluviums and weathered rocks behave very much differently with water. Since most of the tunnels for transport will be in weaker formations below ground water table, tunnelling through such a media can be done easily with earth pressure balancing shields which had very successful been employed in Delhi Metro. The weathered rocks may be considered of very poor quality.

The water tunnels and storage network are to be mostly in rocks. The rocks behaviour may vary widely laterally, however, they are likely to behave consistently in view of being less weathered. The storage system is below 50m, hence the tunnelling may be through fresh rocks. There may be sporadic weathering but it may not affect very much the over all rock mass characteristics. The tunnelling has got to be done under populated area hence tunnel boring machines will be used. The strata have been classified as poor to fair.

Design of Tunnel

The design methodologies are analytical, empirical and design and build. The analytical approach is modeled on the classical theory of elasticity. The rock material has therefore to be assumed as an elastic material that is exceptional rather than rule. The rocks being natural substances are new everywhere and they may not behave as the theory of elasticity may envisage. The analytical tool is very useful for understanding the mechanism of rock mass behavious and its response to excavation. It may be possible to study the effect of shape and size of the opening on stress distribution and areas of high stress concentration. The mechanism of crack initiation, its spread and eventual break up of the rock can also be studied. The results may help in sharpening the engineering judgment process, a very important matter in designing the structures in rocks.

The advent of computers has helped in developing computer models for understanding the tunnel excavation process and material behaviour. The rocks with simple structures may be modeled but the complicated structures are difficult to model. These complicated models are very much prevalent in nature.

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The material model may be elastic, plastic or viscous and the combination of these models. The computer analysis again simplifies the data processing exercise and may yield better results as compared to analytical approach.

The uncertainties of rock mass behaviour had been managed to a great extent by adopting rock classification approaches. These approaches are simple to apply and provide a good tool to pursue designing to begin with. The modern rock mass classification approaches help in assessing the rock mass behaviour and estimating rock pressure and deformation. They also help in designing the temporary as well as permanent supports for any tunnel in a given situation. The application of these approaches needs area specific rock mass parameters to be collected through surface and subsurface Geotechnical explorations. It is sometimes difficult to collect all the needed data. A very experienced rock engineer may help in judiciously assessing the missing data. The analysis leads in assessing Rock Mass Rating (RMR) and Rock Mass Quality (Q). These are usually used to estimate rock pressures and deformational parameters.

In case of soils or highly weathered rocks also the empirical approaches are adopted. Soils have been classified and various tests have been done to assess the soil mass behaviour. Properties like bearing capacity, unconfined compressive strength, cohesion and angle of internal friction can be assessed for designing structures on or within soil mass. Here again the assessed values may only be indicative and they are good enough to prepare initial designs. The empirical approaches are used to design the structures. The data collection, analysis, preparing initial designs help in confidence building, however the engineering judgment provides the final touches to any design to be implemented in actual field conditions.

Underground structures in soil are usually at shallow depths. The subsidence or settlement may take place that may affect the structures at surface. There is a need to assess the shear parameters for estimating subsidence so that appropriate tunnelling and surface protection measures can be adopted. The subsidence etc is be estimated for actual field conditions

Support Pressures

The tunnels to be driven have spans between 6 to 10 m are situated with in a depth of up to 20m. The tunnel support may have to sustain the entire cover pressure. This cover pressure id 5 kg/cm² for most of the soils to be encountered in Delhi areas for transport tunnels

The deep water tunnels will mostly be in rocks. The rocks are poor to fair. The rocks studied in Delhi area have been divided in to three categories and rock pressures etc. are given in the following Table.

Rock Type RMR Q Rock Pressure in kg/cm²

Standup time

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Very poor 0-25 0.1-1.0 1.2-6.0 30 mts for 1 m spanPoor 25-50 1.0-4.0 1.0-1.3 10 hrs for 2.5 m spanFair 50-75 4.0-10.0 0.8-1.1 1 week for 5 m span

The above figures are only for guidance. The poor to fair rocks are likely to be encountered for most areas where water tunnels are proposed. The rock pressures may still be lower if the tunnels are done by tunnel boring machines.

Support Design

The tunnels are permanent structures, hence are to be supported appropriately. The supports are basically of two types i.e temporary and permanent. The temporary supports are installed to prevent the roof fall during construction and they keep the opening safe till the permanent supports are installed. The soils and weathered and disintegrated rocks have been considered as very poor. The following Table suggests temporary supports.

Rock type Shot Crete Rock bolts Bolt lengthVery poor 100 mm 1 bolt per 20 sq. m 3.0 mPoor 50 mm 1 bolt per 25 sq. m 2.5 mFair 50 mm Spot bolt only 2.5 m

The shot crete has to be steel fibre reinforced and be applied soon after the excavation is made and is free from any possibility of rock fall.

Permanent Supports

These supports are mainly steel ribs encased in plain or RCC lining. Supports are to be designed to bear the full rock/soil pressure assessed for different quality of tunnelling media. This is so in view of most tunnels being at shallow depths. These supports may be installed soon after rock bolting and shotcreting operations are over.

The concrete lining may be done after ensuring that the surrounding strata has stablised. This may normally happen after a face advance of about 100 metres in most cases. The lining may be mostly plain cement concrete between 300-500 mm thick. This lining provides a smooth surface to tunnel and helps in improving ventilation and visibility. The lining may also be reinforced if the soil/ rock pressures are high and may cause cracking of the plain concrete lining.

The above designs are indicative only. There is a need to update data through investigation to assess the reasonably accurate behaviour of rocks. The estimated rock pressures may be more refined giving greater confidence to the designers to design optimum supports.

Designing of Parking lots

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The drive in parking lots can easily be constructed in very congested areas. The parking lots are very site specific and their planning and design will depend to a great extent on the surface and sub-surface conditions. Rocky areas like Nehru Place, Karol Bagh, Vasant Vihar and Delhi University are the best places for underground car parks. The Sydney Opera House car park is an important example that can easily be adopted. Other can be gallery and niche type constructed below a rocky area. The planning and designing principles are similar to those adopted for tunnels. It is difficult to propose a plan and design for underground car park is very site specific and need data of the site for proper designing.

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CHAPTER - 9

LEGAL AND SOCIETAL ISSUES

Introduction

Underground habitat for men had been a pre-historic reality. Men considered it safe against weather and enemies. The modern man may have some inhabitations about the underground space. The underground space use sometimes is the last priority but under some circumstances, underground solution is the only one that can fit into the situations.

Urban development, whether planned or unplanned, progressively reduces the space for infrastructure development. The surface space crunch may therefore encourage the use of underground space for less important activities.

The earlier underground space facilities were developed on first come first served basis. This led to unplanned development creating problems for the concerned persons and the government. The planned way of underground space development is now being advocated. The legal framework is now being formulated for underground space construction.Living underground is still a psychological block and this issue had been gone into in details. The advantages and disadvantages are being evaluated and the safe purposes for which the space can be used are being found out. Any space needing short duration stay underground are most favoured like storages, substations, garages, service tunnels and defence installations. Ways and means are being found out to encourage human activities underground so that the space crunch on the surface can be eased out. In the following paragraphs legal and human behaviour aspects are being discussed.

Legal Issues

In a society there has to be a legal frame work for any activity, because this may affect the comforts as well as the property right of individuals in a situation where surface and sub-surface constructions are involved. The legal frame work must answer all questions and must be capable of redressing the grievances of the concerned persons. In the following paragraphs some important issues are being discussed.

Limit of ownership

The person who owns the surface may claim ownership to the sky and depths. This claim is legally accepted in British, French, German, Greek and Roman law since centuries. In the countries that have centrally planned economies and ownership of resources, private land ownership may be restricted. All underground and air space is therefore publicly owned. This however does not restrict the right of the surface owner to be compensated for any subsurface use

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by any other persons. The state organizations have made laws to resolve the issue of subsurface. In U.S.A, the rights have been decided. In case of air space if it is interfered substantially with the owner’s enjoyment of his property, it would be considered as trespass. However in case of subsurface the American law recognizes the owners right up to the depths. In India, the subsurface rights are restricted and all resources like minerals down below are owned by the state.

Sub-Surface Ownership Rights

This is a complex issue and only conventions have been developed. In the countries where the space is public owned, it is easier to frame regulations for ownership rights. The local bodies may frame local by laws to regulate the sub-surface construction, with adequate compensation to the surface owned for any risk involved in underground space development by any other agency that has no surface rights. In some countries, any space below a depth of 6 metres is state owned and the surface owners rights are restricted below this depth.

Plans & Permits

The local bodies usually have plans for surface use. In view of prospects of sub-surface use in future there is a need to develop sub-surface use plans. Special permissions may be needed to develop sub-surface space. The issues of public safety on surface as well as underground has got to be gone into thoroughly and legal framework has to be developed. The permits for sub-surface construction be given on its basis. The subject is still under development and it is not possible at this stage to give more details. The countries where underground space development is taking place, the permissions for construction are given on case to case basis after fully satisfying the affected persons about any inhabitations they may have.

Risk to Nearby Structures

Any digging near or below an existing structure causes ground movement detrimental to the safety of the existing structures. The legal issues may be due to any fear of damage to surface structure. The structure may be a building or a monument, under these circumstances, the permission to construct underground space is given only after ascertaining the potential of affecting near by buildings. The construction for any underground structure under such circumstances is not normally given. Even if such construction is permitted, who bears the liability for damage to the near by structures. There has to be a legal remedy for such a situation and liability of the persons be defined clearly.

Environmental Issues

Underground construction lowers the local ground water table. During construction, the ground water collected may have to be pumped out. This pumping out of ground water may lead to settlement of surface structure. There has to be technical solutions for such a contingency with a legal provision.

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The ground water may get polluted by the pollutants generated by the underground facility. This aspect also needs careful attention and remedies found.

The environmental pollution caused by the excavated muck should also be attended to. There is a need to assess the environmental impact and ways and means be found to manage the impact.

City Area Remodelling

Cities all over the world grew with time. The open space in the cities shrink and the old buildings are now found to have over lived their utilities. Remodelling and reconstruction are usually done periodically. The usefulness of underground space is being understood well now and the remodeling process is taking the development of underground space a very important part of remodeling. The underground space provides more space down below the surface and is most environment friendly.

The remodeling process must have the support of the people living on or working in that particular area. The local government may enact special legal provisions to give effect to remodeling which include the development of huge underground space. Such remodelings had been successfully done in Chicago, Boston, Paris, Tokyo and Nagoya. The developments in these areas provided underground parking lots and markets.

In many old city areas, people may feel the necessity of remodeling. The remodeling is therefore most opportune time when the underground space development may take place. There is a huge scope for remodeling in old areas of Indian mega cites.

Global Scenario

The use of underground resources, like minerals, water, gas and oil is a part of policies of various nations. There are legal provisions to exploit the resources for the progress of any country. The use of underground space for societal purposes is a new concept and it is being gradually recognised to be useful. The underground space is therefore another form of resource which can bring cosmic benefits to the society. The underground space development is now taking the shape of legal identity. Following are the points which need to be considered for formulating a legal frame work for underground space development.

Special Permission Needed

The underground space development has to be a regulated activity like mining. The mining is done under special permits and conservation and safety codes have got to be followed. For underground space development rules, regulations

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have got to be evolved. The existing mining codes may have to be modified to cover the underground space development activity.

Land use Regulations

In many countries surface land use zoning extends to sub-surface also. How for or upto what extent surface regulations may extend to sub-surface is a debatable issue. There is thus a need to evolve sub-surface land use planning and regulations.

Environmental Control

There is a need to develop environmental control and protection regulations. Here again the legal frame work existing for mining may be very useful.

The issue of development of underground space is very much talked about in the context of urban infrastructure development. There is a need to evolve an approach which may help in framing legislations under which the underground space development can be regulated.

Context Delhi

In India, the state has the right to own what lies down below. Mineral concession act and treasure trove acts amply clarify the legal provisions. In the light of these acts it may be possible to device a legal frame work to promote the underground space development. The subsurface planning and detailed Geotechnical surveys are to be done. Sub-surface land use plans may be the part of city land use planning. Delhi is on the threshold of underground space development and hence there is a need to undertake sub-surface planning and enacting legislations to promote underground space construction.

Societal Concerns

The societal concerns are mostly the personal safety and property loss. These concerns are there during construction as well as while operations. The following points need careful evaluation.

(1) Safety regulations(2) Collapses and accidents(3) Water in rush(4) Fire(5) Psychological(6) Physiological

Safety Regulations

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Under construction as well as being underground are considered risky. The underground construction is done by intrinsically safe equipments used in a manner which prevents to a great extent any accident. Careless working may be a cause or there may be accidents which may or may not be prevented. The safety regulated for man and machines are there to be observed.

In traffic tunnels, there are safety regulations for drivers. These regulations are to be followed and progressively updated. These mostly pertain to speed limits, lane changing and overtaking. The entry to the tunnel is the place where most of accidents occur.About 3000 traffic tunnels are under operation all over the world. Vast experience is available on safety aspect. With the introduction of intellect transport system, the travel through a traffic tunnel may be lot more easier. There are many people underground who man the smooth operations. Their personel safety is also codified and they are well trained to handle difficult situations down below. In India, the underground city transport is yet to take shape. There will be a need to develop safety regulations and traffic norms for the tunnels. Tunnels operators as well as the drivers have to learn the safety code well to ensure a hassle free travel through tunnels.

Collapse and Accidents

They may occur both during construction as well as operations. The design and construction is done in such a way as to eliminate any possibility of collapse. The running vehicles may hit the side wall or collide with reach other. There has to be preventive measures to guard against it.

Water In Rush

The ground water and surface water may get collected into the tunnel. The tunnel may get flooded due to sudden ingress of surface water. Usually there is well laid drainage system and the collected water is pumped out so that the tunnel remains dry. The sudden in rush is a difficult situation to deal with. This may be very common on sea shores or river banks. Appropriate measures are taken to prevent the flooding. This mechanism is an in built feature of a road tunnel.

Fire

Accidental fire in vehicles passing through tunnels had been reported in literature. Same fire caused deaths and damage to tunnel system. Most important case is of Mount Bloc Tunnel under Alps between Italy and France. A margarine loaded truck accidentally caught fire. The smoke caused many deaths as a number of cars got trapped in the tunnel. The rescue and relief operations had been a difficult task. Rescue and relief operations are rather difficult underground, hence preventive measures are adopted to ward of any eventually. After this incident transport of any inflammable substance through the tunnel was banned. There are a thousands of transport tunnel for roads and rail transport.

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The cases of fire are very rare. The design of transport vehicles and other system installed in the tunnels are to be intrinsically safe, pre-empting any fire incident.

Psychological

To be underground or pass through underground has a major psychological effect on man. Mentally the underground evokes dislike and psychologically a man has many inhabitations like being unsafe, left and trapped in a hostile environment. Studies had been conducted to understand the human behaviour underground. It revealed that a short stay underground is acceptable however longer stay or working are disliked. Some people talk of being compensated for working underground. The usual motorist in underground is only for a short period, however for the staff manning the underground system, feel unsafe.

Physiological

The man underground suffers no physical effects. The usual blood chemistry remains unchanged provided the underground space is well ventilated and lighted. The studies done on this aspect therefore not support the notion of being harmed physically under the normal conditions.

Surface-Underground Debate

It is an on going activity and people debate its merits and demerits. Inspite of this major cities are favouring underground mode of transport. This system helps faster transport with in a busy city. There are certain advantages of going underground.

(1) Faster travel(2) Earthquake resistant(3) Infrastructure development facilitated(4) Energy Economy(5) Improved Aesthetics on surface(6) Long life of underground system

In the following paragraphs the above points are further elaborated.

Faster Travel

Surface roads are rarely signal free and a moving car has to halt at many traffic signals coming on its way. There is thus time loss. In New York, the average travel speed of a transport bus is about 5km per hour. In Delhi, it is over 10 km. This speed is going down at an accelerated pace. In underground the travel is almost signal free and a motorist can definitely move at a faster pace as compared to what he can do on surface. Dangerous driving, sometimes slowing down the traffic on surface is not permitted underground hence, the traffic passes in a stream lined manner, increasing over all speed. The tunnels can connect

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two points through a shortest passage, as the construction underground can be done without any hindrance which is usually posed by any structure on surface. This ultimately shortens the travel distance, reducing travel time.

Earthquake Resistant

The underground structures are less prone to damages caused by earthquakes. In the recent past there had been two major earthquakes which caused extensive damage to the transport infrastructure. The Los Angles earthquake brought down numerous fly overs, which were designed to be earthquake resitant. The flyovers collapsing led to disruption of road transport over large areas. The Japanese designed better flyovers subsequently, which were severely damaged by Kobe earthqake. There was a 60 km long elevated road, a rail line and elevated tracks of bullet trains between Kobe and Osaka. All these collapsed due to earthquake. The massive collapses disrupted the entire transportation system in and around Kobe. The relief and rescue operations were hindered very much. The repair of the entire elevated transport structure took very long time for traffic restoration.In Los Angle as well as Kobe the underground transport infrastructure remained largely intact and could soon be put to use after minor repairs. The road tunnels below Rokko Mountain in Kobe were intact.

Delhi has over 80 fly overs and many more are planned to be constructed in near future. The city lies in zone 4 which is considered prone to earthquake in the region as 6-6.5 magnitude. This magnitude is very much critical to the fly overs. The collapsed flyovers and near by buildings may lead to blockage of roads hampering rescue and relief operations. The repairs and restoration of system may take a very long time because the fallen debris of the structures may have to be removed first. The underground road transport system in Delhi may be a step towards achieving preparedness against any earthquake threat.

Infrastructure Development facilitated.

The unplanned urbanization of Delhi is causing scarcity of surface space for infrastructure development like transport, water supply, public services and space for commercial activities. The underground placement of critical facilities like transport and water supply may help to a great extent the resolution of problems of Delhi citizens. Literally another Delhi lies below ground for the development to improve the quality of life of persons living in Delhi.

Energy Economy

It is a well known fact the energy needs per capita reduces with rise in population density. Denser the population lesser the energy needs. The large cities are growing laterally and vertically. The lateral expansion drastically changes the land use. The agricultural or forest land is therefore diverted to the urbanisation. This changes the ecological paradigm of the nearby area. People live in such areas, away from their work place. They commute to the down town for work and the trip length for the travel increases. If they live near by, the density of

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population may increase, but it will decrease the transport expenses. The infrastructure in the densely populated areas may be built underground to sustain large population. This infrastructure, may be parking lots, road tunnels, services conduits and utility space for services. Shopping and commercial space can also be developed underground to facilitate people.

The underground space development will thus be very energy efficient. Closer living concept may help in preserving the agriculture and vegetation around the cities. Energy economy will be there due to less fuel consumption. The over all effect will be less pollution and improvement in the ecology of the area.

Improved Aesthetics on surface

Delhi is a historical city. There are evidences of people living for past 5000 years. Numerous archeological monuments are there. Lutyens Delhi is an internationally acclaimed land mark is in Delhi. The modern high rise building has also contributed to the sky line of Delhi. The fly overs are gradually changing the landscape and over a period of time my prestigious buildings may disappear in a maze of high rises and fly overs. The heritage conscious people are very much concerned about preserving the old monuments, which dot the city. Many monuments have already been encroached upon, due to pressure of population and infrastructure development.

There is a possibility of developing under ground roads in place of fly overs. This may help in changing the landscape of Delhi and enthuse the heritage conscious people.

Long life of Underground Structures

Cave temples of Ajanta, Ellora and Elephanta are more than 1000 years old and they still stand to survive for at least 500 years. The underground structures are not directly exposed to weathering due to rains, heat and humidity. The London tubes started in 1863 and by the turn of 19 th Century most of the tube tunnels were in place. These have survived over one hundred years and there are no sign of deterioration. The engines, rolling stock, ventilation, lighting, drainage and signaling arrangements have changed umpteen number of times all these years, however, the tunnels remain as such. The underground structures survive longer as compared to their surface counter parts. In Delhi the metro tunnels and any traffic tunnel made in the future may have a very long life.

Disadvantages

Any underground construction is difficult to dismantle. The underground construction may therefore be done only in situations where the underground construction is the only solution.

For psychological reasons, people do not like being underground, hence the use of underground space is very much restricted.

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It is costly to construct as compared to surface structures.

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CHAPTER - 10

CONCLUSIONS AND RECOMMENDATIONS

The study has been aimed at proposing a couple of useful underground facilities for easing the problems of Delhi. Conceiving and designing any underground structure need a very through sub-surface Geotechnical investigations. The design has to be very reliable to ward off any problem that may arise while working below a busy city. The present study has been based upon the meager data available in the published literature and various reports prepared for construction of structures and probing the ground water. The data so obtained is very scanty and inadequate to proceed with actual design. However, it is good enough to conceptualise some underground facilities like storage of water and road tunnels to ease the problems of Delhi. The following broad conclusions and recommendations can be drawn from the study.

Conclusions

(1) Water and transport are the two main problems of Delhi.(2) The floodwater that no body welcomes during rainy season can be interned

into special network of underground tunnel. This water can be pumped out when needed and from any place in the storage area.

(3) The proposed underground water storage system is feasible and can be constructed economically within the Aravali rocks that cover about 20% of the Delhi subsurface.

(4) The storage will help in improving the ground water scenario which is going down very fast.

(5) Delhi can have its own source of water and its dependence on the mercy of the neighbouring states may reduce considerably.

(6) Road tunnels are feasible at many places to improve traffic condition with in busy city areas.

(7) Road tunnels may also help in improving the landscape of Delhi that has been very much affected by fly overs.

(8) Underground parking lots can be constructed for busy business areas of Delhi to reduce the dangers posed by off street car parking.

(9) The underground infrastructure concept will reduce pressure on land and may help in saving what ever little greenery left in the city.

Recommendations

(1) Area wise subsurface investigations be done to assess the behaviour of soil/ rocks to help in planning and designing of underground structures.

(2) Delhi master plan should have chapter on subsurface utilities. This plan may reserve locations and fix priorities for sub-surface development.

(3) There is a need to develop legal codes for underground space development.(4) Public debate be encouraged to project the virtues and vices of underground

facilities and their adaptation by people.

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Godard, J.P. and Terean, J.P (1995): Underground Car Parks in France – a case study, Tunneling and Underground Space Technology, Vol.10, No.3, PP-311-320.

Hanmura, T. (1993): Japan’s New Frontier Strategy: Underground Space Development, Tunneling and Underground Space Technology, Vol.5, No.1/2, PP-13-21.

Hacket, C.,(1881), “Geology of Aravali region, Central & Eastern.” Rec. G.S.I, Vol. 14(4), pp. 279 – 303.

Heron, A.M., (1917), “Geolgy of North – Eastern Rajasthan & adjacent districts”, Mem. GSI, Vol.45 (1), pp. 1 –28.

Nisi, J., Kam, F and Ozawa, K.(1990): Rational use of Urban Underground Space for surface and sub surface activities in Japan, Tunneling and Underground Space Technology, Vol.5, No.1/2, PP-23-91.

Sterling, R.L and Cormody, J.(1993): Underground Space Design, Van Nostrand Reinhold, New York, P-328.

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