final project

1

Table of Contents Section 1 ........................................................................................................................................................ 3

Introduction .................................................................................................................................................. 3

Background ................................................................................................................................................... 4

Objectives ..................................................................................................................................................... 4

Methodology ................................................................................................................................................. 4

Broad Band Analysis ...................................................................................................................................... 5

Broadband Selection ................................................................................................................................. 7

Decision Matrix ......................................................................................................................................... 9

Risk Analysis ............................................................................................................................................ 10

Narrowband Analysis .................................................................................................................................. 13

Earthworks .............................................................................................................................................. 15

Existing Structures .................................................................................................................................. 15

Right of Way ............................................................................................................................................ 16

Drainage .................................................................................................................................................. 16

Maintenance Costs ................................................................................................................................. 17

Economic Analysis ................................................................................................................................... 17

Financial Analysis .................................................................................................................................... 18

Cost Analysis ........................................................................................................................................... 20

Decision Matrix ....................................................................................................................................... 22

Risk Analysis ............................................................................................................................................ 24

Environmental Impact Assessment ............................................................................................................. 41

Anticipated Impacts Due To Highway Construction Project ................................................................... 41

Encroachment on precious ecology .................................................................................................... 41

Adverse impact on historical/cultural monuments ............................................................................ 41

Water quality impacts due to construction sites: ............................................................................... 41

Air Quality Impacts during Construction ............................................................................................. 42

Effect on Natural resources ................................................................................................................ 42

Conclusion ................................................................................................................................................... 42

SECTION 2 ................................................................................................................................................... 44

Introduction. ............................................................................................................................................... 44

Design Criteria ............................................................................................................................................. 44

2

Design Traffic Volume ............................................................................................................................. 44

Design Speed ........................................................................................................................................... 44

Grade ................................................................................................................................................... 45

Methodology of Route Location ................................................................................................................. 45

Plotting of Horizontal Curves: ................................................................................................................. 45

Plotting of Vertical Curves ...................................................................................................................... 46

Horizontal Curvature ................................................................................................................................... 46

Horizontal Alignment .............................................................................................................................. 47

Results ..................................................................................................................................................... 48

Sample Calculation .............................................................................................................................. 48

Vertical Alignment ...................................................................................................................................... 49

Stopping Sight Distance .......................................................................................................................... 49

Results ..................................................................................................................................................... 50

Sample Calculation: ............................................................................................................................. 50

Cross Section ............................................................................................................................................... 51

Drainage .................................................................................................................................................. 52

Safety Features ........................................................................................................................................... 53

Soil Failure ............................................................................................................................................... 53

Driver Safety ........................................................................................................................................ 54

Conclusion ................................................................................................................................................... 55

References .................................................................................................................................................. 56

Appendix ..................................................................................................................................................... 56

3

Section 1

Introduction Travel to and from the East West Corridor to Maraval, Trinidad, is currently facilitated by two

routes out of Maraval, two routes out of Port-of-Spain, and the Lady Young Road. These routes

are often congested at peak hours during the week, and for most of the day during weekends and

public holidays. Special events have also resulted in massive jam density causing untold

inconvenience and distress to users. Thus, an alternative route that traverses from the Lady Young

Road to the Maraval Road is required to be designed in order to alleviate the current traffic

congestion.

A highway by definition is a thoroughfare, route, or way on land between two places which has

typically been paved or otherwise improved to allow travel by some conveyance. Highways are

one part of transportation infrastructure, and transportation is one aspect of meeting human

needs. In order to construct new highways, there is an entire design process in which a

considerable amount of planning is done. This process is comprised of two major portions: 1) the

route location and 2) the geometric alignment. Under the general heading of the route location

stage, there are two main processes that must be undertaken: 1) a broad band analysis and 2) a

narrow band analysis. This portion of the report deals with the extensive route location stage in

which a tentative general area for the final alignment is selected.

In the route location stage, the first thing that must be done is properly study the area in which

the required route must be designed. The given area subtended by the Maraval Road and Lady

Young Road, consists of Cascade and St. Anns: two very densely populated residential areas.

Directly north of this area is the St. Anns peak: a very steep and mountainous terrain that goes in

excess of 300 metres in height above sea level. It is also important to note that there are largely

forested areas around the residential areas, as well as existing rivers in the general area, namely

the St. Anns river and the Arapita river.

4

Once the observation and study of the general area has been accomplished, the broad band

stage can now begin; this stage consists mainly of dividing the broad study area into large

(broad) bands that can be studied and assessed individually in order to determine which area is

Background Travel to and from the East West Corridor to Maraval, Trinidad, is currently facilitated by two routes out

of Maraval, two routes out of Port-of-Spain, and the Lady Young Road. These routes are often congested

at peak hours during the week, and for most of the day during weekends and public holidays. Special

events have also resulted in massive jam density causing untold inconvenience and distress to users.

Objectives

The objective of this project is to plan and produce an alternative route between the Lady Young

Road and Maraval in order to reduce the congestion and travel time on the current route.

Establish a suitable broadbands with the aid of Google Earth satellite imagery with at least

three alternatives along with a risk analysis

Produce a route alignment within the established broadband utilizing the concepts of

horizontal and vertical curves in accordance to appropriate design guidelines.

Produce detailed drawings of the roadway with setting out data, profiles of the existing and

proposed roadway, location and type of water crossings, retaining structures and safety

features along with cross sections.

Methodology

1. Using Google Earth satellite imagery, three broad bands with the widths ranging from

500m to 500km were set out in the area of interest. Each broadband was then analyzed

and rated and the optimum broad band was selected.

2. After establishing the optimum broadband, two narrow bands were selected within it.

These narrow bands were then analyzed, rated and compared under more detailed criteria

which includes the Economic, Financial, Environmental, Physical, Social, Technological

factors and a Risk Analysis which was given a 40% weighting in any considerations done.

5

3. A route alignment was then designed using the ideal narrow band. The geometric

alignment was that designed in accordance to the criteria set out in the American

Association of State Highway and Transport Officials (AASHTO 2001) design handbook.

4. Engineering drawings including cut and fill, vertical and horizontal curves and profile views

were produced.

Broad Band Analysis

Fig. 1 showing the location of the broad band alternatives.

6

Fig. 2 showing the geographical map along with the broadband alternatives

Fig. 3 showing the Hydrological map along with the broadband alternatives

7

Broadband Selection

Physical suitability in addition to the Triple bottom line factors were used in order to analyze rate and

compare the broadband. The triple bottom line factor are:

1. Environmental

2. Social

3. Economical

4. Physical

Environmental Factors

During construction, sufficient care for the environment must be undertaken in order to ensure

the sustainability of the project. Special considerations must be made to meet the needs of the

design without heavily compromising the standards of the environment such as foliage, wild life

and also to prevent obstruction or contamination to any natural water ways and drainage that

may be present.

Social Factors

The Social factor deals with the impact of the construction to the community and those in close

proximity to it. Construction brings about a lot of noise, pollution and many undesirable factors

which negatively affect residents in the area. Also, it may be necessary for land to be acquired

from residents to facilitate possible widening or realignment of the road. Some social factors

include; travel time, background views along travels, noise levels, pollution during construction

and pollution of water supply

8

Economic Factors

The economic factors play a pivotal role for any construction project to determine the economic

feasibility of said project. In highway construction, it is important to minimize the total project

cost and duration, while providing a quality facility. Also, minimizing vehicle operating costs,

which means; the shorter and less steep the route, the less cost in fuel. This also results in less

pollution and increased leisure time as well as lower vehicle maintenance costs. It is also equally

important to minimize the cost of environmental mitigation.

Physical Factors

The physical considerations deal with the stability of the soil which if unstable would require the

use of stabilizing structures such as retaining walls. The geology of the construction area such as

fault lines, slope of the land and rock types present. The type of soil which contributes to the soil

stability and facilitation of drainage

The vegetation and land use of the area- the removal of which may affect the potential for soil

erosion and lead to land slips.

The amount of rainfall that the area receives as well as the level of the water table level in the area

both relate to the drainage as the soil in the area may not allow for quick infiltration of surface

water which may cause pooling problems on the roadway.

9

Decision Matrix

ObjectivesMeasure of

EffectivenessDescription

1 Economic Incurs the least amount of cost

2 SocialIncreases quality of life in surrounding

communities

3 Physical Incurs the least amount of physical risk

4 EnvironmentalIncurs the least negative environmental

impact

Table 1. Measures of Effectiveness

I II III

1 Economic 6 4.5 4

2 Social 8 7 5

3 Physical 7 7 6.25

4 Environmental 7 6.5 5

NumberMeasure of

Effectiveness

Broadband Alternatives

Objective RankingRelative

Weight

Weighting

Factor

1 3 3 20.0

2 3 3 20.0

3 1 5 33.3

4 2 4 26.7

TOTAL: 15

Table 3. Ranking and Weights

I II III

1 20.0 15.0 13.3

2 26.7 23.3 16.7

3 38.9 38.9 34.7

TOTAL 85.6 77.2 64.7

Measure of

Effectivene

ss

Alternatives

Table 4. Point Score for Alternatives

10

Risk Analysis

Broadband 1

Environmental

Risk Event Likelihood Impact Severity Risk Level

Suspension of works during heavy

rainfall.3 3 9

Traversing over the mountain will

increase work time and constuction

risks (higher elevations)

3 5 15

Landslides, Mudslides during

construction2 5 10

Social

Clearing of land for construction:

Visual Pollution; Construction

is unsightly and can affect

businesses in the nearby

region

3 4 12

Noise Pollution can disrupt

public productivity3 3 9

Construction of roadway:

Displacement of private

residents and worplaces4 5 20

Environmental

Displacment/Destruction of Flora in

construction path5 3 15

- Removal of wildlife habitats 2 2 4

Noise Pollution 4 3 12

Pollution of waterways 3 3 9

Air pollution:

- Incurrence of respiratory ailments

due to inhalation of dust particles3 3 9

Total Risk Level124

11

Broadband 2

Broadband 3

Environmental



rainfall.3 3 9




3 5 15


construction3 5 15

Social





region

3 3 9





Environmental






Air pollution:



Total Risk Level130

12

Broadband 1 was shown to have the lowest risk level and the highest score in the decision matrix. Hence

it was chosen for further analysis.

Environmental



rainfall.3 3 9




5 5 25


construction5 5 25

Social





region

2 2 4





Environmental








Total Risk Level131

13

Narrowband Analysis

Narrowband Alternative I: This corridor passes close to mountain and provides a more direct route from

Lady Young to Maraval

14

Narrowband Alternative II: This corridor passes close to the existing path to Maraval

This corridor passes close to mountain and provides a more direct route from Lady Young to Maraval.

The factors considered in the following matrix and risk analysis included:

Economic

Financial

Social

Environmental

Physical

Technological

After selecting an effective broadband that satisfied the requirements of the analysis, it was

necessary to undertake the narrow band stage of the route alignment. A narrow band is of the

order five to ten times the final alignment; hence it shows the specific area within the chosen

broad band that would be directly affected by the construction of the final alignment. In this

stage of the analysis, we were required to select alternative narrow bands from the optimum

corridor that would be most effective to construct within. In the area between the Lady Young

15

Road and Maraval Road, two suitable narrow bands were plotted out such that certain criteria

were considered; the criteria of selection of the narrow band are stated below:

1) Earthworks (amount of cut and fill)

2) Existing structures

3) Right of way

4) Drainage

5) Maintenance costs

These considerations were applied more in depth under the individual data considerations for

the weighted narrow band analysis; in this section, they would each be introduced.

Earthworks

One of the most costly aspects of any road works project is the amount of cut and fill that needs

to be done in order to accommodate the foundation and structure of the proposed road. Cutting

existing earth requires hiring the use of plant/equipment that would be able to remove the earth

in order to achieve the necessary grade; the grading process is not cheap as the rental cost of

equipment is high and the time required to grade existing earth may be extensive, depending on

the type of soil present at the site as well as the length of the proposed narrow band. On the

opposing side, filling existing earth also is costly because even though it is easy to quantify the

amount of fill required, more fill that the calculated volume is required as compaction of the

loose fill must be taken into consideration. Thus the volume of fill required as well as the

equipment necessary to compact the fill are contributing factors to the cost of filling. In order to

minimize costs of earthworks, narrow bands were chosen such that they traversed along a

relatively constant grade along the entire route. By doing this, longer narrow band lengths were

obtained; narrow band 1 was approximately 3.15 km in length while narrow band 2 was 3.26 km.

Existing Structures

Considerations of existing structures within the narrow bands were also made. It was almost

impossible to avoid existing structures due to the fact that the chosen broadband was mainly

consisting of built up areas. It would be a major project delay if the final alignment were to pass

16

through currently existing structures, thus requiring time to be put into acquiring rights to

demolish structures and acquire land. It is for this reason that both narrow bands were routed in

order to avoid existing structures in the presently built up areas.

Right of Way

Right of way takes into consideration the legal right for a road to be routed through parcels of

land belonging to residents in the area. For the chosen broadband, right of way is a major cause

of concern due to the fact that any alignment through the residential area would infringe the

right of ownership of parcels of land by residents, thus requiring land to be acquired. In major

construction projects, acquiring land is a very costly and time consuming process as the legal

procedure to acquire land is very drawn out. For major roadwork projects, land is almost always

able to be acquired; however the process would become longer if there is resistance from the

owners of the land to forfeit their parcels. Even if the final alignment is routed along existing

roadway, there still may be the necessity to acquire land in order to widen the roads to

accommodate heavier traffic. While there is still a risk of the necessity of land acquisition, it is

more feasible to route the alignments along existing roads, as was done by the proposed narrow

bands.

Drainage

One of the greater causes for concern would be the resulting drainage situation, should an

alignment be constructed within the chosen narrow band. Drainage has already been accounted

for in the design of the currently existing road, thus any cut, fill or change of gradient of the

current earth would have an impact on the volume of flow through culverts and drains. It is for

this reason, that in the final alignment, grades of road must be selected such that effective

drainage of the roadway can be obtained. Constructing roads results in removing existing soils

which may have allowed drainage through ground seepage and changing of the existing grade

would both have an impact on the volume of direct runoff that would flow through the drains. It

is for this reason that due care and consideration must be given to re-designing the existing

drainage routes; this would therefore result in an increase in the financial cost of the project, as

it is impossible to neglect drainage designs of the alignment.

17

Maintenance Costs

Lastly, we must consider the long term maintenance cost of the chosen route. The maintenance

cost of a project is one of the major deciding factors in determining the economic feasibility of

the proposed narrow band. Major factors that affect the maintenance costs along the design life

include repair costs due to natural occurrences such as slope failures and general wear and tear

of the road from daily usage over an extended period of time. For our proposed narrow bands, it

has been estimated that the maintenance cost of the route would be 5% of the original

construction cost, leading narrow band 1 to have a lower maintenance cost.

Economic Analysis

While the financial section of the narrow band analysis was concerned mainly with up front, initial

project costing, the economic analysis is concerned with the long term financial aspects of the

proposed roadway. The economic considerations deal mainly with aspects such as, design life and

maintenance cost of the roadway, cost/benefits and rate of return for the proposed roadway, long

term improvement to industrial and agricultural production, funding to reduce environmental

hazards in the long term and reducing vehicle maintenance costs over the roads design period.

Overall, the economic analysis of the narrow bands deals mainly with the long term financial

benefits of the proposed roadways to be built in the tentative narrow bands.

Under the economic examination of the narrow bands, we deal with maintenance cost over the

design life of the roadway and the estimated vehicle operation costs incurred by motorists. It has

been estimated that the maintenance cost for the proposed narrow bands in the given area would

be approximately 5% of construction costs of the roadway. On this basis, it can be clearly noted

that the narrow band that possessed a lower construction cost to build within it would have a

lower maintenance cost over its design period; this would lead narrow band 1 to be more

economically feasible in incurring an estimated lower maintenance cost over its design period. In

addition to maintenance costs, vehicle operating costs must also be considered, as it is an indicator

of how efficient the road is in transporting motorists from point A to point B with least effects on

their vehicles. Vehicle operating costs have various contributing factors, including the gradient of

18

the road, roughness of the road surface, curvature of the road and the amount of speed changes

done by the vehicle while traversing the route. Taking these factors into consideration, vehicle

maintenance costs for the area of the proposed roadway have been generalised as roughly $2 per

kilometre of road. Based on this estimated vehicle operating cost, it can be said that narrow band

1 would contribute to a lower cost as it has a generally shorter length of road. The unit cost of

construction, which has been derived by dividing the machine rates by the production rates, is

generally the same for both narrow band 1 and 2; hence it is not a major economic factor that

needs to be considered.

It is also necessary to pay attention to other economic factors, such as improvement to agricultural

and industrial productivity, while balancing the cost to mitigate environmental impacts after

constructing the road. It is noted that building a road through narrow band 1 would allow for an

increase in industrial productivity, as it would allow easy access to large businesses located nearby;

agricultural productivity would also be improved as a road built on the peak of the mountain would

allow easy access to agricultural lands there. Lastly, the economic analysis deals with the cost for

the mitigation of environmental hazards and disturbances. This encompasses all environmental

risks that can be encountered should a road be built in the proposed narrow band and the funding

that would need to be allocated in order to mitigate these risks.

After comparison of both narrow bands in terms of their economic benefit, it can be seen that

narrow band 1 has a better economic standing than its alternative under the aforementioned

headings. It must be noted that both financial and economic factors will be discussed further and

with more accuracy after the actual alignment of the proposed road way is set out.

Financial Analysis

In the scope of the project, it is quite necessary for us to consider the financial factors that could

impact the progress of the project, as without proper funding, major construction projects cannot

be undertaken. These factors come mainly in the form of construction costing, which includes the

costing of plant/equipment, cost of cut and fill, payment for labour and funding for property

acquisition. In conducting a feasibility study of a project, construction cost is of utmost importance

as it necessary to inform the client, who would be funding the project, of the amount of money

19

needed to be put in so they can decide whether or not the project is worth undertaking. While the

estimated construction cost is quite important, of equal importance is the funding source (the

client), the current financial ecosystem and the economic conversion rates. However, as pertains

to the current project being undertaken, it would be more necessary to consider construction cost,

due to the fact that the three aforementioned factors would be common for all alternative narrow

bands under analysis.

In the process of planning out road works, one of the most influential factors in construction is the

soil type that must be built on as it dictates how much soil preparation (in terms of compaction of

soil, backfill etcetera) must be done before construction can begin. However, in the present

situation, both alternative narrow bands are mapped out on relatively similar soil types, mainly

consisting of alluvium rock. As per the Department of Civil Engineering in the University of the

West Indies, St. Augustine, estimated costing per kilometre of road for building on alluvium rock

have been obtained and calculations are shown below it is noted that building on alluvium rock

has an estimated value of $1.4M per kilometre of road works. In examining narrow band 1 with

an average length of 3.15 km, the estimated construction cost of road works would be $4.4M. On

the other hand, building on narrow band 2 with an estimated length of 3.26 km, the estimated

construction cost of road works would be $4.56M. We must also examine the cost of undertaking

earthworks for the construction of the roadway. It is important to note that in doing this, the

method of selecting an equilibrium length was used, in which an attempt was made to reduce

earthworks by sacrificing short road lengths. In inspecting the cost of earthworks, it must be noted

that narrow band 1, while attempting to stay as close as possible to reducing property acquisition

and keeping the road shorter, there was a compromise in the amount of earthworks needed to be

done; this can be seen when cutting a section through the existing path of the narrow band. It can

be seen that the existing ground is quite undulating, thus more attention must be paid to cut and

fill with regards to this narrow band. Narrow band 2, however, sacrificed road length in order to

obtain less need for cut and fill.

20

Cost Analysis

Narrow Band 1 total distance = 3.14 km

Construction Cost

Construction cost for alluvium soil = $M1.4 TT/km

alluvium soil would cost = $M1.4 TT x 3.14km

= $M4.4TT

Total construction cost = $M4.4TT

Maintenance cost.

Maintenance cost = 5% of total construction cost

= 5% x $M4.4 TT

= $M0.22TT

Vehicle operating cost.

Vehicle operating cost = $2.30 per km

= $2.30 x 3.14km

= $7.22 per trip across the path

21

Narrow Band 2 total distance = 3.26 km

Construction Cost.

Construction cost for alluvium soil = $M1.4 TT/km

3.26 km of alluvium soil would cost = $M1.4 TT x 3.26km

= $M4.56 TT

Total construction cost = $M4.56 TT

Maintenance cost.

Maintenance cost = 5% of total construction cost

= 5% x $M4.56TT

= $M0.23 TT

Vehicle operating cost.

Vehicle operating cost = $2.30 per km

= $2.30 x 3.26km

= 7.50 per trip across the road

22

Decision Matrix

I II

1 Financial 4 3.5

2 Economic 3 3

3 Social 4 4

4 Physical 3 3

5 Technological 3 3

6 Environmental 3 2.5

7 Risk Analysis 5 5

NumberMeasure of

Effectiveness

Alternatives

Objectives RankingRelative

Weight

Weighting

Factor

1 1 7 22.6

2 2 6 19.4

3 5 3 9.7

4 2 6 19.4

5 7 1 3.2

6 4 4 12.9

7 4 4 12.9

TOTAL 31

I II

1 22.58 20

2 19.35 19

3 9.68 10

4 19.35 19

5 3.23 3

6 12.90 11

7 12.90 13

TOTAL 100.00 95

Alternatives

Point Scores for Alternatives

Measure of

Effectiveness

24

Risk Analysis

Narrowband 1

Economic

Risk Event Likelihood Impact

Severity

Risk Level Mitigation,

Prevention,

Control

Likelihood after

Mitigation

Impact Severity

after Mitigation

Risk Level

after

Mitigation

Demand for environmental

mitigation and compensation

3 4 12 Education of

public on

benefits of

roadway and

expected

effects

3 2 6

Change in alignment due to

unforeseen conditions:

- Delay in project

completion time

3 4 12 Perform

necessary site

investigations

in order to

address

problems

during design

stage

2 2 4

25

- Prolonged use of leased

equipment

2 3 6 Perform

necessary site

investigations

in order to

address

problems

during design

stage

2 2 4

Increased cost due to legal

action taken by (third party)

community members

2 4 8 Education of

public and

regular

progress

announceme

nts

2 3 6

Relocation of

homes/businesses

compensation

3 4 12 Placing of

persons in

areas more

convenient to

lifestyles or

business

1 2 2

Social

26

Clearing of land for

construction:

- Dislocation of persons

settled in nearby areas causing

emotional distress

3 4 12 Giving of

sufficient

notice and

available

options of

alternative

residents

2 3 6

- Loss of arable land that

may have been used as source

of income

3 4 12 Provision of

alternative

crop land

3 3 9

- Interference with

culturally, historically significant

sites

2 3 6 Monumentin

g of

significant

areas if

possible,

preservation

of discovered

artifacts

1 3 3


27

- Noise from construction

activities causing distress to

surrounding communities

4 3 12 Use of sound

walls, work

schedule

implemented

at times

convenient

for

surrounding

community

2 2 4

- Respiratory issues arising

due to dust from construction

processes

2 4 8 Wetting of

site to reduce

spread of

dust

1 3 3

- Restricted access to

certain areas of land due to

enforce safe distance from

construction site

3 2 6 Education of

public on

necessity of

safety

measures

2 2 4

Steep Terrain:

- Risk of landslips resulting in

danger to site personnel

3 5 15 Carry out soil

stability

studies and

construct

2 3 6

28

effective

earth

retaining

structures.

- Risk of damaging equipment

due to mountainous terrain

4 5 20 Only operate

machinery

rated for the

specific

terrain

3 3 9

Risk of encountering

underground waterways,

aquifers during cutting process

2 3 6 Prior in-depth

hydrogeologic

al study

1 3 3

Environmental Impacts

Deforestation:

- Loss of agricultural lands for

food production

4 3 12 Provision of

alternative

crop land

3 3 9

- Removal of wildlife habitats 3 3 9 Creation of

protected

wildlife

3 3 9

29

reserve in

other location

Noise Pollution 4 3 12 Use of sound

walls, work

schedule

implemented

at times

convenient

for

surrounding

community

3 4 12

Pollution of waterways 3 3 9 Wetting of

site to reduce

spread of

dust and

effective

clean up of

site

2 3 6

Air pollution:

30

- Incurrence of respiratory

ailments due to inhalation of

dust particles

3 3 9 Wetting of

site to reduce

spread of

dust

2 2 4

- Damaging local flora due to

coating of tree leaves with dust

particles

4 3 12 Wetting of

site to reduce

spread of

dust

2 2 4

Project Delay

Delayed processes in property

acquisition, due to resistance

from residents and drawn-out

negotiations

3 4 12 Education of

the public of

the benefits

of the project

2 3 6

Equipment malfunctions 3 4 12 Prior

Inspection

and regular

maintainace

during project

duration

2 3 6

31

Delayed approval of project

from regulatory bodies, such

as Town and Country, EMA,

OSHA etc

4 4 16 Early

document

submition

and constant

follow up

3 3 9

Total Risk Level 250 Total Risk Level

After

Mitigation

134

Narrowband 2

Economic

Risk Event Likelihood Impact

Severity

Risk Level Mitigation,

Prevention,

Control

Likelihood after

Mitigation

Impact Severity

after

Mitigation

Risk Level after

Mitigation

Demand for environmental

mitigation and compensation

5 5 25 Education

of public on

benefits of

roadway

and

3 2 6

32

expected

effects

Change in alignment due to

unforeseen conditions:

Delay in project

completion time

3 4 12 Perform

necessary

site

investigatio

ns in order

to address

problems

during

design

stage

2 2 4

Prolonged use of leased

equipment

2 3 6 Perform

necessary

site

investigatio

ns in order

to address

problems

2 2 4

33

during

design

stage

Increased cost due to legal

action taken by (third party)

community members

4 4 16 Education

of public

and regular

progress

announcem

ents

3 3 9

Relocation of

homes/businesses

compensation

3 3 9 Placing of

persons in

areas more

convenient

to lifestyles

or business

2 2 4

Social

Clearing of land for

construction:

34

- Dislocation of persons

settled in nearby areas

causing emotional distress

3 4 12 Giving of

sufficient

notice and

available

options of

alternative

residents

2 3 6

- Loss of arable land that

may have been used as

source of income

3 3 9 Provision of

alternative

crop land

2 2 4

- Interference with

culturally, historically

significant sites

4 4 16 Monumenti

ng of

significant

areas if

possible,

preservatio

n of

discovered

artifacts

3 3 9


35

- Noise from

construction activities causing

distress to surrounding

communities

4 3 12 Use of

sound

walls, work

schedule

implemente

d at times

convenient

for

surrounding

community

2 2 4

- Respiratory issues

arising due to dust from

construction processes

2 4 8 Wetting of

site to

reduce

spread of

dust

1 3 3

- Restricted access to

certain areas of land due to

enforce safe distance from

construction site

3 2 6 Education

of public on

necessity of

safety

measures

2 2 4

Steep Terrain:

36

- Risk of landslips resulting in

danger to site personnel

2 5 10 Carry out

soil stability

studies and

construct

effective

earth

retaining

structures.

2 3 6

- Risk of damaging equipment

due to mountainous terrain

4 5 20 Only

operate

machinery

rated for

the specific

terrain

3 3 9

Risk of encountering

underground waterways,

aquifers during cutting

process

2 3 6 Prior in-

depth

hydrogeolo

gical study

1 3 3

Environmental Impacts

Deforestation:

37

- Loss of agricultural lands for

food production

3 3 9 Provision of

alternative

crop land

2 2 4

- Removal of wildlife habitats 3 3 9 Creation of

protected

wildlife

reserve in

other

location

3 3 9

Noise Pollution 4 3 12 Use of

sound

walls, work

schedule

implemente

d at times

convenient

for

surrounding

community

3 4 12

38

Pollution of waterways 3 3 9 Wetting of

site to

reduce

spread of

dust and

effective

clean up of

site

2 3 6

Air pollution:

- Incurrence of respiratory

ailments due to inhalation of

dust particles

3 3 9 Wetting of

site to

reduce

spread of

dust

2 2 4

- Damaging local flora due to

coating of tree leaves with

dust particles

5 4 20 Wetting of

site to

reduce

spread of

dust

3 3 9

39

Project Delay

Delayed processes in

property acquisition, due to

resistance from residents

and drawn-out negotiations

4 4 16 Education

of the

public of

the benefits

of the

project

3 3 9

Equipment malfunctions 3 4 12 Prior

Inspection

and regular

maintainac

e during

project

duration

2 3 6

Delayed approval of project

from regulatory bodies, such

as Town and Country, EMA,

OSHA etc

4 4 16 Early

document

submition

and

constant

follow up

3 3 9

40

Total Risk

Level

279 Total Risk Level

After

Mitigation

143

Narrow Band 1 was chosen as it scored higher in the decision matrix and was shown to be of lower risk after mitigating steps have been taken.

41

Environmental Impact Assessment

Anticipated Impacts Due To Highway Construction Project

Encroachment on precious ecology:

The proposed routing of the highway encroaches upon precious ecological resources, including forests

and streams. This also disturbs the natural habitats of animals living on the encroach land. The

ecological disturbance is likely to occur.

The construction activities will drive some wildlife away from their habitats, particularly the birds that

live on the hill. Many birds within about 500 m of the proposed roadway will leave their currently

roosting and feeding places and move away.

During road construction, the vegetation on the acquired land will be destroyed, and the local

ecosystem is changed. In addition, the destruction and fragmentation effect of the road construction

may diminish the habitats for some of the animal species, so that there may not be enough roosting

places any more for them to survive. During operation, the traffic noise, traffic lights at night and vehicle

emissions may cause some adverse impacts on the wildlife around the road.

Adverse impact on historical/cultural monuments:

The nearby structures to highway projects are adversely affected due to the pollution and

environmental disturbances created by the project. During the construction phase, huge amount of CO2

(Carbon Dioxide) and CO (Carbon Monoxide) gases are released into the atmosphere. The gas poses a

threat to cultural landmarks as they are made up of lime which reacts with these gases in presence of

water/moisture.

Water quality impacts due to construction sites:

Wastewater and hazardous materials may drain into streams and drainage areas, causing pollution to

surface water and groundwater. This is particularly true for large construction sites, construction

campsites, and staging areas where workers, construction equipment, and building materials are most

concentrated.

42

Air Quality Impacts during Construction Construction activities particularly earthworks; increased traffic and the use of cement, asphalt, and

other building materials will produce excessive airborne dust and toxic asphalt fumes, causing a major

impact on air quality within the project area.

Effect on Natural resources The highway will disrupt some existing irrigation systems, particularly below the hilly areas where the

road will be constructed. This interception will also affect the existing flood relief channels and natural

drainage of the area.

Conclusion After comparing each broad band under the general headings of the triple bottom line: social,

economic and environmental factors in conjunction with physical characteristics of each, an

evaluation matrix based on these factors was constructed which was used to give scores to each

broadband. The economic aspect of the broadband was weighted as the most imported factor,

while physical characteristics were weighted second and social and environmental factors were

placed third. From this analysis, broad band 1 was calculated to have the highest point score,

thus becoming the chosen broad band in which to construct a narrowband. A risk assessment of

each broad band was subsequently done, in which all possible risks that could occur within each,

was identified and given a risk score. It was determined that broad band 1 also had the lowest

risk score, thus determined to be the least likely to pose serious risk.

Once broad band 1 was chosen, two alternative narrow bands within the chosen broad band

were constructed. These narrow bands were planned out such that they have minimal

earthworks, short lengths and suitable soil types such that they reduce maintenance costs, and

existing roadways were utilized where possible in order to reduce interference of right of way

and existing structures. The narrow bands were analyzed under the broad headings of financial,

economic, physical, environmental, social and technological characteristics. Additionally, a risk

assessment was done for each narrow band in which the initial and mitigated risk scores were

calculated for each. After scoring for each of the aforementioned considerations, a final point

43

score was obtained for each, which showed that narrow band 1 was the higher scored of the 2

alternative narrow bands, thus leading it to be the chosen narrow band in which to construct the

final alignment.

44

SECTION 2

Introduction. The geometric design of the highway alignment was done in accordance to AASHTO standards.

AASHTO is an American organisation responsible for setting design standards which all engineering

works must comply to. In roadway design, these include, design speeds, topography, safety and

earthworks. Some design guidelines were also taken from the recommended Manuals &

Guidelines on Road Engineering for Development published by TRL Ltd, specifically, from the Road

Safety Guidelines chapter (pg. 2848 3394).

Design Criteria

Design Traffic Volume

The proposed route is expected to have a projected average daily traffic flow of 400 2000

vehicles. This range was also used for the economic analysis of the narrow bands to access vehicle

operating costs.

Design Speed

Design should be consistent with a specific design speed selected as appropriate for

environmental and speed is a selected speed used to determine the various design features of the

roadway. Geometric design features terrain conditions.(ASSHTO 2001) The design speeds were

chosen with reference to Chapter 5, Local Roads and Streets

In the mapping of the horizontal and vertical alignments, the main objectives were:

The minimisation of cut and fills in order to reduce cost

The avoidance of possibly unstable areas

The safety and comfort of the driver along the entire route

45

Grade Different grades were selected throughout the entire route. The grades chosen were defined by AASHTO

guidelines. They are dependent on the terrain and the design speed involved. The maximum grade for the

road designed was 16

Methodology of Route Location The following steps were undertaken in order to plot the centreline of the proposed roadway.

A contour interval spacing of 30m was selected

Circle with radius CI/G was calculated and used to plot out alignment by moving from contour to

contour within the boundary of the radius extension in order to comply with the required maximum

grade of 14%=0.14.

R = CI/G = 25/0.14 215

Where necessary, alignment was plotted along the contours in order to get to a point where

movement from one contour to another is possible within the radius boundary.

Plotting of Horizontal Curves:

The radii of each curve was calculated using the following formula below (sample calculations are

shown in latter sections). The values of e and f were selected based on the design speed.

=2

127( + )

Using AutoCAD, the Fillet tool was used to trim each intersection point with the appropriate radius.

46

Plotting of Vertical Curves

Civil 3D was used to generate the profile view of the existing ground, EG. on a grid where the

vertical scale was in 30 m intervals and the horizontal scale at 100m intervals.

The length L of the chord on which the vertical curve is suspended was calculated from the

equation below and was drawn onto the vertical intersection points in AutoCAD.

=

||

The vertical curve was then generated using the ARC command in AutoCAD.

Horizontal Curvature.

A horizontal curve provides a transition between two tangent strips of roadway, allowing a vehicle to

negotiate a turn at a gradual rate rather than a sharp cut. The design of the curve is dependent on the

intended design speed for the roadway, as well as other factors including drainage and friction. These

curves are semicircles as to provide the driver with a constant turning rate with radii determined by the

laws of physics surrounding centripetal force. . There are three main factors to consider in horizontal

curvature:

Superelevation, e Which is the amount of rise seen on an angled cross-section of a road given a

certain run, otherwise known as slope. The presence of superelevation on a curve allows some of

the centripetal force to be countered by the ground, thus allowing the turn to be executed at a

faster rate than would be allowed on a flat surface.

Side Friction factor, f refers to the need for the vehicle to have friction with surface on which it is

travelling.

Velocity, v Depends on the type or terrain, purpose of the road and the location of the roadway.

47

Horizontal Alignment

According to the AASHTO design guidelines, the recommended maximum grade for an Urban Collector in

mountainous terrain is 14%

The velocity, side friction and superelevation values were selected based on the design speed which was

in turn selected by terrain type. The design values used in the geometric design of this highway are

summarized below.

Table Showing Selected Design Values

The radius for each curve, R, was calculated using the formula below:

=2

127( + )

The length of the curve, L was calculated using the formula below:

= 2 360

The Tangent length, T, was calculated using the formula below:

= 2

Velocity (km/h) 50

Superelevation, e 0.1

Side Friction, fs 0.16

Maximum Grade, G 14%

Contour Interval, CI 30

Design Values

48

Results

Sample Calculation:

Curve #1

Angle of directional change, = 32.88

Design Speed, V = 50 km h

Superelevation, e = 0.10

Friction factor, f = 0.16

Min. Radius =V2

127(e+f)=

202

127(0.10+0.16)= 75.7m rounded to 80 m

Radius used = 135 m

Tangent length, T = R tan (

2) = 135 tan (

32.88

2) = 39.84 m

Beginning of Curve, PC = PI T = [0 + 461.75] 39.84 = [0 + 421.91]

CURVE

POINT OF

INTERSECTIO

N

CENTRAL

ANGLE VELOCITY

SIDE

FRICTION

SUPER

ELEVATION

RADIUS

Min

RADIUS

USED

TANGEN

T

BEGINNING

OF CURVE

LENGTH

OF

CURVE

END OF

CURVE

# PI V f e Rmin R T PC L PT

1 0+461.75 32.88 50 0.16 0.1 80 135 39.84 0+421.91 77.47 0+499.39

2 0+659.16 30.23 50 0.16 0.1 80 135 36.46 0+622.70 71.23 0+693.92

3 0+883.71 7.4 50 0.16 0.1 80 135 8.73 0+874.98 17.44 0+892.42

4 1+104.34 39.86 50 0.16 0.1 80 135 48.95 1+055.39 93.92 1+149.31

5 1+320.67 29.54 50 0.16 0.1 80 135 35.59 1+285.08 69.60 1+354.68

6 1+582.00 15.19 50 0.16 0.1 80 135 18.00 1+564.00 35.79 1+579.79

7 1+765.34 45.19 50 0.16 0.1 80 135 56.18 1+709.16 106.48 1+815.64

8 1+992.33 12.65 50 0.16 0.1 80 135 14.96 1+977.37 29.81 2+007.17

9 2+201.41 23.47 50 0.16 0.1 80 135 28.04 2+173.37 55.30 2+228.67

10 2+410.73 36.47 50 0.16 0.1 80 135 44.48 2+366.25 85.93 2+452.18

11 2+644.30 12.96 50 0.16 0.1 80 135 15.33 2+628.87 30.54 2+659.40

12 2+867.87 60.55 50 0.16 0.1 80 135 78.81 2+789.06 142.67 2+931.73

13 3+150.76 16.62 50 0.16 0.1 80 135 19.72 3+131.04 39.16 3+170.20

14 3+426.93 50 0.16 0.1 80 135 0.00 3+426.96 0.00 3+426.93

HORIZONTAL CURVE DATA

49

Arc Length, L =2R

360=

2 135 32.88

360= 77.44 m

End of Curve, PT = PC + L = [0 + 421.91] + 74.44 = [0 + 499.39]

Vertical Alignment Two types of vertical curves exist: Sag Curves and Crest Curves. Sag curves are used where the change in

grade is positive, such as valleys, while crest curves are used when the change in grade is negative, such

as hills. Both types of curves have three defined points: PVC (Point of Vertical Curve), PVI (Point of Vertical

Intersection), and PVT (Point of Vertical Tangency). PVC is the start point of the curve while the PVT is the

end point.

Stopping Sight Distance

Sight distance is dependent on the type of curve used and the design speed. For crest curves, sight

distance is limited by the curve itself, as the curve is the obstruction. For sag curves, sight distance is

generally only limited by headlight range. AASHTO has several tables for sag and crest curves that

recommend rates of curvature, , given a design speed or stopping sight distance. These rates of

50

curvature can then be multiplied by the absolute slope change percentage, to find the recommended

curve length, .

Results

Sample Calculation: Curve #1

Design Speed = 50 km h

Type of curve: Crest

Design K value for sag curve = 44

Point of Intersection, PVI = 0 + 540.008

Absolute Difference of Gradients, |A| = |G1 G2| = |3.317 (11.995)| = 8.678

Length of Chord, L = K |A| = 44 8.678 = 555.376 ft = 182.210 m

Beginning of Vertical Curve, BVC = PVI L

2= [0 + 540.008] (

182.210

2) = [0 + 096.355]

CURVEPOINT OF

INTERSECTIONVELOCITY

GRADE OF

TANGENT

GRADE

OF

TANGEN

T

TYPE OF

CURVE

DESIGN

VALUES

DIFFERENCE

IN GRADES

CHORD

LENGTH

BEGINNING

OF CURVE

HALF

CHORD

END OF

CURVE

# PVI V(km) G1 (%) G2 (%) K |A| L BVC L/2 EVC

1 0+540.008 50 -3.317 -11.995 Crest 44 8.678 182.210 0+096.355 91.105 0+278.745

2 1+263.784 50 -11.995 1.292 Sag 44 13.287 278.986 0+698.827 139.493 0+997.113

3 1+624.357 50 1.292 5.223 Sag 64 3.932 82.555 1+215.633 41.277 1+298.187

4 1+986.663 50 5.223 13.841 Sag 64 8.617 180.941 1+414.490 90.470 1+594.430

5 2+714.852 50 13.841 5.066 Crest 64 8.775 184.248 1+659.376 92.124 1+843.624

6 2+950.026 50 5.066 -6.835 Crest 64 11.901 249.882 2+576.869 124.941 2+826.751

7 3+050.348 50 -6.835 -10.899 Crest 44 4.064 85.332 3+199.884 42.666 3+285.216

8 3+265.048 50 -10.899 0.000 Sag 44 10.899 228.846 3+402.507 114.423 3+631.353

VERTICAL CURVE DATA

51

End of Vertical Curve, EVC = PVI +L

2= [0 + 540.008] = (

182.210

2) = [1 + 278.745]

Cross Section According to the New Zealand State Highway Geometric Design Manual (2002), the cross section

of a road is a vertical plane at right angles to the road control line (centreline). It is standard

practice for the cross sections to be viewed in the direction of increasing stationing and shows

traverse details of the road way. The locations of the cross sections for the proposed carriageway

are detailed below:

Type of Cross

Section Stationing (km)

Elevation of

Ground Level (m)

Elevation of

Proposed Road (m)

Cut and Fill 0+600 84.12 84.34

Fill 0+700 68.34 75.19

Cut 1+200 65.94 62.98

Fill 1+400 63.34 68.97

Fill 3+000 131.47 133.96

Cut 3+300 118.93 113.67

52

Drainage

Provision for adequate drainage is of paramount importance in road design and cannot be

overemphasized. The presence of excess water or moisture within the roadway will adversely affect the

engineering properties of the materials with which it was constructed. Cut or fill failures, road surface

erosion, and weakened subgrades followed by a mass failure are all products of inadequate or poorly

designed drainage. Many drainage problems can be avoided in the location and design of the road. When

the location of a road way is being chosen hydrological factors such as water table level, natural steam and

drainage patterns must be considered. When it comes to road design the cross slope is critical to the design

a long with effect drains and channels to effectively and safely move away from the road protect the road

sublayer.

Pavement cross slope is an important cross-sectional design element. The cross slope drains

water from the roadway laterally and helps minimize ponding of water on the pavement. This prevents

maintenance problems. On roadways with curbed cross sections, the cross slope moves water to a

narrower channel adjacent to the curb, away from the travel lanes, where it can be removed. Cross

slopes that are too steep can cause vehicles to drift, skid laterally when braking, and become unstable

when crossing over the crown to change lanes. These conditions are exacerbated by windy conditions

which are common in Trinidad. Both maximum and minimum criteria exist for cross slope. The cross slope

for the proposed road was selected to be 2% in accordance to the AASHTO 2002 guidelines for

mountainous roadways.

53

Safety Features

Soil Failure

As shown on the cross section drawings, the mountainous terrain on which the proposed

alignment is defined resulted in large amounts of cut and fill in some areas which will increase the

risk of soil and slope failure. Therefore, safety features have to be implemented in these areas that

help to minimise soil instability. Below shows some of the problems associated with cutting and

filling on a slope as well as well as safety features to combat them.

Methods that can be used to reduce the risk slope and soil failure include the use of:

54

Stepped slopes- however, this greatly increases the amount of earthworks that need to be

performed

Retaining Walls

Crib walls these are much cheaper to construct than retaining walls.

Vegetation Inexpensive and sustainable. Those with deep roots can provide stability for

long periods of time.

Geotextiles Also sustainable Gabion walls cheaper and easier to construct than

retaining walls.

Driver Safety

Safety features implemented for driver safety:

Picture Above shows Guard Rails that should be installed as a safety feature to prevent Roadway

Departure hazards.

55

Sign should be clearly displayed along the route alerting drivers to potential hazardous conditions along

the route.

Conclusion

From the analysis performed on the area of study, it was concluded that narrow band 1 would be

used to design the highway for the alternative route form Lady Young Road to Maraval..

The geometric alignment was designed in accordance to the AASHTO highway manual. The

design was found optimum and sustainable design minimizing damage to the environment and

the negative effects to the community. The detailed drawings were produced.

56

References

1. Engineering Economic Analysis, Ninth Edition. Newnan Donald G; Eschenbach Ted G;

Lavelle Jerome P. Oxford University Press. 2004

2. Trinidad and Tobago Soils map and Topographical map

3. White, John A., Kenneth E. Case, David B. Pratt and Marvin H. Agee. 1939. Principles of

economic analysis. 4th ed. New York: John Wiley and Sons, Inc.

4. Highway engineering handouts and spreadsheets (V.O.C). Department of Civil

Engineering. University of the West Indies.

5. Civil Engineering Design 2 Handouts. Department of Civil Engineering. University of the

West Indies.

6. Slope Stabilization and Stability of Cuts and Fills.

http://ntl.bts.gov/lib/24000/24600/24650/Chapters/M_Ch11_Slope_Stabilization.pdf

British Columbia. How Vehicle Emissions Affect

Us.http://www.env.gov.bc.ca/epd/bcairquality/topics/vehicle-emissions-impacts.html

7. David Levinson.Superelevation.http://www.learncivilengineering.com/wp-

content/uploads/2012/11/superelevation.pdf

8. http://safety.fhwa.dot.gov/geometric/pubs/mitigationstrategies/chapter3/3_crossslope.c

fm

Appendix

final project

Documents

risk analysis

narrowband analysis

economic analysis

financial analysis

cost analysis

broad band analysis

decision matrix

table of contents section