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MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION

(Autonomous)

(ISO/IEC-270001 – 2005 certified)

SUMMER-14 EXAMINATION

Subject code: 12139 Model Answer Page No: 1/ 19

Important Instructions to examiners:

1) The answer should be examined by keywords and not as word-to-word as given in the

model answer scheme.

2) The model answer and the answer written by candidate may vary but the examiner may try

to assess the understanding level of the candidate.

3) The language error such as grammatical, spelling errors should not be given more

importance. (Not applicable for subject English and communication skill).

4) While assessing figures, examiner may give credit for principal components indicated in the

figure. The figure drawn by candidate and model answer may vary. The examiner may give

credit for any equivalent figure drawn.

5) Credits may be given step wise for numerical problems. In the some cases, the assumed

constants values may vary and there may be some difference in the candidates answer and

model answer.

6) In case of some questions credit may be given by judgment on part of examiner of relevant

answer based on candidates understanding.

Q. 1 A) Attempt any THREE of the following. 12

a) Classify roads according to Nagpur plan.

Classification roads according to Nagpur plan:- According to Nagpur plan, the roads

were classified into five categories as follows:

1) National Highway (NH)-

The main highways connecting major ports , forigion highways capital of large

states industrial and tourist centre. Including roads for strategic moment.

2) State Highway (SH) - arterial roads of state connecting with the national highway of

adjacent state , district head quarters & important cities within the states.

3) Major District Roads (MDR) – important within a district connecting with the main

01

Mark

each

( any

four )

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highway of a district , areas of production and markets.

4) Other District Roads (ODR) - Road surveying rural areas of production and

connectiong them with outlet to market centres , taluka head quarders, block development

head quarters or other main roads

5) Village Roads - connecting villeges or group of villeges with each other.

b) Progress of any country can be judged by good network of roads - Explain

Good network of roads facilitates good transportation which contributes to the

economics, industrial, social and cultural development of the country. Transportation is vital

for the economic development of any region since every commodity produced whether is

food, clothing, industrial products or medicine needs transport at all stages from production

to distribution. In the production stage, transportation is required for carrying raw materials

like seeds, manure, coal, steel, etc. in the distribution stage, transportation is required from

the production centre.

The inadequate of transport system, of a country indicates its economic and social

development. Overall economic progress can be achieved, only if reasonably adequate

transport facilities are made available between the village and other district head quarter and

commercial centres. Road development generates considerable employment potential. The

road networks have also be supplemented with express ways to keep pace with the

requirement of uninterrupted movement of fast vehicles along the arterial roads.

02

02

c) State the scales recommended for Key map and Index map.

Scales recommended for Key map:-Key map is drawn to the scale 1:250000. Shows the

location of the road with respect to important towns, industrial centres, etc. In short, it

provides bird eye view of the project.

The Key map shows the kilometerage from the beginning to the end and generally drawn to

a scale of 1:50000.

Scales recommended for Index map:- It is drawn with a scale of 1 cm = 0.5 km.

02

02

d) Define Camber. State types of camber with sketch.

Camber:- Camber is defined as ‘ the convexity provided to the surface of carriageway OR

the rise given to the centre of carriageway above its edge on straight portion of a road OR

the slope provided to the cross section of the road.

Types of camber:- 1) Composite camber 2) sloped or Straight camber.

3) Two straight line camber 4) Elliptical barrel camber 5) Parabolic barrel camber

01

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01

Mark

each

( any

three

type )

B) Attempt any ONE of the following. 06

a) Calculate stopping sight distance for a two way traffic on a single lane road. The

design speed is 80 kmph. The reaction time of the driver is 2.5 sec. The coe. of

friction is 0.6, break efficiency is 50%.

V= Speed of the vehicle in kmph = 80 kmph

t= reaction time of the driver= 2.5 sec.

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f = Coefficient of friction = 0.6

we know,

Stopping sight distance (SD) = Reaction Time + Breaking distance

= (0.278 V.t) + ((0.278V)2 /2gf)

= (0.278*80*2.5) +(( 0.278*80)2 / (2*9.8*0.6))

= 139 + 42.05

=181.05 m

When the traffic is single lane but in two ways, the stopping sight distance

= 2 * stopping distance

= 2 * 181.05

= 362.1 m

02

02

02

b) Design the super-elevation on a horizontal curve having a radius of curvature of

300 m. the design speed is 80 kmph and transverse coefficient of friction is 0.15.

R = radius of the curve = 300 m

V = Speed = 80 kmph

f = coefficient of friction = 0.15

e + f = V2 / (127 * R)

e + 0.15 = 802 / (127 * 300)

e + 0.15 = 0.1679

e = 0.1679 – 0.15

e = 0.0179 per meter carriage way.

02

02

02

Q2. Attempt any FOUR of the following. 16

a) State any four factors affecting alignment of road in plain area.

Factors affecting alignment of road in plain area:-1) Purpose and class of road:- The

alignment should be selected according to the purpose and class of road.

2) Obligatory points:-The alignment should pass through obligatory points such as

intermediate important towns, group of villages and places of commercial, social, political

and military importance.

3) Need of traffic:- The alignment should suit the needs of traffic.

4) Gradient:- The alignment should have gradient not steeper than the ruling gradient.

5) Curves:- The alignment should have flat curves.

6) Sight distance:- The alignment should have provide good sight distance.

7) Obstructions:- The alignment should be free from obstructions.

8) Number of drainage crossings:- The alignment should have minimum number of

drainage crossings.

01

Mark

for

each

( any

four )

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9) Railway and river crossing:- The alignment should cross railway line or river at right

angles.

10) Formation bed:- The alignment should run on good soil as far as possible. The

alignment should have

11) Costly land dense forests, etc.:- The alignment should not involve much costly and

cultivable land and avoid dense forests.

12) Earthwork:- The alignment should have less earthwork. And so on

b)Define highway location. State different surveys to be carried out while locating a

highway.

Highway location:- The process of marking the centre line of a road finally on the ground

is called highway location.

For locating a highway, the following surveys are undertaken

1) Reconnaissance survey.

2) Preliminary survey.

3) Location survey.

4) Engineering survey

5) Detailed survey

02

02

( any

four )

c) Differentiate flexible and rigid pavement w.r.t. any 8 points.

Sr.

no.

Points of

comparison

Flexible Pavements Rigid Pavements

1. Initial cost Low High.

2. Life span Short. Long.

3. Thickness More. Less.

4. Joints. Not required Essentially required.

5. Skill and

supervision

Moderate skill and less

supervision is required

High degree of skill and more

supervision is required.

6. Repair works. Easy Difficult.

7. Subgrade A good subgrade is required A good subgrade is not

necessary.

8. Durability Less More.

9. Resiliency More resilient Less resilient.

10. Corrugations Develop corrugations Do not develop corrugations.

11. Tractive

resistance

More. Less.

12. Maintenance

cost

High. Low.

½

mark

For

each

point

( any

eight )

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d) State the requirements of a good road pavements.

Requirements of a good road pavements:- It should 1) be strong and durable.

2) provide an impervious and sanitary surface.

3) be smooth enough to provide low tractive resistance but not to smooth which may

become slippery.

4) be cheap and easy in construction.

5) not develop corrugations.

6) not cause glare in the sun.

7) provide good visibility at night.

8) be suitable for all types of traffic.

9) provide a safe and comfortable riding surface under all weather conditions.

10) have long life.

11) have low maintenance cost.

½

mark

For

each

point

( any

eight )

e) Write the sequential steps/operations involved in the construction of WBM road

with sketch.

Sequential steps/operations involved in the construction of WBM:-

a) Preparation of foundation for Receiving the WBM Course :- i)The Foundation for WBM may be sub grade , sub-base & base coarse.

ii) The foundation layer is prepared to the required grade.

b) Spreading of coarse Aggregate :- i) The Coarse aggregate are spreads uniformly to proper profile to even thickness upon the

prepared foundation after spreading the coarse aggregate properly compaction is done by

roller having a capacity of 6 to 10 tones.

c) Application Screening :-

After the coarse aggregate are rolled adequately, dry rolling is continue as the screening are

spread.

d) Sprinkling & Grouting :- After the application of screening, the surface is sprinkled with water, swept & rolled.

e) Application of Binding Material :- After the application of screening and rolling binding material is applied at uniform & slow

rate at two or more successive thin layers.

f) setting & Drying :-

After final compaction the WBM course is allowed to set over night.

02

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Cross section W.B.M road

02

f) Describe Los Angles abrasion test.

Los Angles abrasion test.:1) Aggregate sample weighing 5 kg or 10 kg depending on the

grading is put in the machine along with the abrasive charge.

2) The machine is rotated at speed of 30 to33 r.p.m. for the specific number of revolutions

(500 or 1000) depending on the grading of aggregate.

3) Now, the sample is taken out of the machine and sieved through 1.7 mmI.S. sieve and the

weight of aggregate passing through 1.7 mm sieve is determined . Let this weight be W2 kg.

Abrasion value = (W2/W1)*100%

Where W1 is the weight of the sample put in the machine.

For cement concrete construction, Abrasion value should not be more than 16%. For

bituminous mixes, Loa Angeles abrasion value for surface courses may be allowed up to

30% and for base courses, this value may be allowed upto 50 %

02

02

Q 3) Attempt any Four of the following 16

a) Write steps to be carried out in viscosity test of bitumen.

Viscosity Test:

Viscosity is defined as the resistance to the flow of liquid bitumen. Viscosity at any

specified temperature is measured by recording the time in seconds for a give quantity of

bitumen at the same temperature to flow through an orifice of standard dimensions into a

receiver as shown in fig. below. The longer the time required, the higher is the viscosity of

the material. The test values are expressed in seconds. (I.S:1206-1958)

03

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01

b) State different types of tests carried on aggregates which are used for pavement

construction.

Different types of tests carried on aggregates:

1. Abrasion test

2.Crushin Test

3.Impact Test

4.Shape Test

5.Soundness Test

6.Specific gravity Test

7.Water Absorption Test

8.Stripping value or bitumen affinity test

½ Mark

for

each

C ) State the Sequential operation involved in the construction of Cement Concrete

Road

Sequential operation involved in the construction of Cement Concrete Road :

1. Preparation of subgrade and sub base

2.Placing of forms

3.Watering the prepared subgrade or sub base

4.Mixing and placing of Concrete

5.Compaction and finishing

6.Belting, brooming and edging

7.Curing

8.Opening to traffic

½ Mark

for

each

d)Draw a neat sketch of Longitudinal drain and Cross drain

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Longitudinal drain and Cross drain

02

Mark

for fig.

02

Mark

for

labeling

.

e) With a neat sketch, explain Surface drainage system in Urban Area.

Surface drainage system in Urban Area: The surface drainage of urban area is different

than that of the rural area. In urban area the land width is limited and the open drains cannot

be provided as they are unsightly, occupy more space and serve as a source of danger to the

traffic. Therefor the underground drains or sewers are provided. In urban area the surface

drainage is provided either in the form of catch basin or inlets as shown in fig.

02

01

01

f) Enlist any eight important factors considered for road alignment.

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Important factors considered for road alignment:

1.Need of Traffic

2.Purpose and class of road

3.Obligatory points

4.Curves

5.Gradients

6.Sightdistance

7.No.of Drainage Crossing

8.Railway and River Crossing

9. Availability of road materials

10.Ashetical aspect

1/2

marks

each

(Any 8

points)

Q4) A- Attempt any three of the following 12

a) Define Gradient. State Factors which govern the selection of gradient.

Gradient: The rate of rise or fall along the length of the road with respect to the horizontal

is known as gradient.

Factors governing the selection of gradient :

1. Nature of ground

2.Nature of Traffic

3.Drainage of Traffic

4.Type of road surface

5.Total height to be covered

6.Road and Railway intersection

7. Bridge approaches

01

1/2

marks

each

(Any 6

points)

b) State IRC recommendation for different typs of gradients in plain and

mountainous area

IRC recommendation for different types of gradient :

S.N

.

Types of

Terrain

Gradient

Ruling Limiting Exceptional

1 Plain Area 3.3 % (1 in

30) 5 % (1 in 20)

6.7 %( 1 in

15)

2 Mountainous

Area 5 % (1 in 20)

6 % (1 in

16.7)

7 % ( 1 in

14.3)

02

02

c) State object of providing super –elevation.

Objects of providing super elevation :

1. To introduce the centripetal force to counteract the effect of the centrifugal

force.

2. To ensures smooth and safe movements of passengers and goods on the road.

3. To help fast moving vehicles to negotiate a curved path without overturning and skidding.

4. To drained off rain water easily.

01

01

01

01

d) Define lead ,lift ,balancing of earthwork,spoil bank.

Lead: It is defined as the horizontal distance through which the excavated material is

moved for embankment.

Lift: It is defined as the vertical distance through which the excavated material is moved.

Balancing of Earth Work: When the excavated earth from cutting is utilized in filling i.e

01

01

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in forming embankment, then it is known as balancing of earth work.

Spoil Bank: The bank constructed from surplus excavated earth on the side of road cutting

parallel to its alignment is known as spoil bank.

01

01

Q 4 – B) Attempt any one of the following 06

a)Suggest a suitable curve for an alignment having a rising gradient of 1 in 75

followed by a rising gradient of 1 in 80 .Draw neat sketch.

Suggested suitable curve is Vertical Type Summit Curve

04

( Neat

sketch

with

labels)

02

b) Sketch label a standered C/S of NH in embankment.

Standard Cross Section Of NH In Embankment.

02

marks

for

sketch

02

marks

for

labels

02

marks

for

dimensi

ons

Q5) Attempt any four of the following 16

a) Draw a neat C/s of hill road Showing Components of road.

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02

marks

for

sketch

02

marks

for

labels

b) State types of curves on hill road and with neat sketch explain hair-pin bend

/curve

Type of curves on hill road are as follows :-

1 )Sailent carve:-

I)The carves having their convexity on the outer edges of a hill road are called as Sailent

Curves.

2 ) Re-entrant Curves:-

I)The Re-entrant Curves in Which their convexity on the inner edge of a hill road

01

01

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3)Hair pin carve:-

I) Hair pin carve on a hill Road Which Change its direction through an angle 180 degree.

II) Hair pin bends With long arms and further Spacing Should be Preferred.

III) Straight length between the length of circular and Transition curves.

Iv) The length of Hair pin bends depends upon hill slopes to avoid costly protective

measures between the upper and lower arms of the bends.

01

01

c)Define landslides, state causes of land distance .

Landslides :- The term land slide is used it indicate the downward and outward movement

of slop forming material composed of natural rock soil artificial fills or combination of both.

Causes of landslides :- i) Vibration caused by blasting & earthquakes.

ii) Formation of falls in bedding planes of strata due to seepage peculating ground water.

iii) Increase in water content of soil.

iv) Increase in weight due to external load of traffic.

02

02

d)Define design speed ,sight distance .

1)Design Speed:- The overall Design Of geometrics of any highway is a function of the the design speed .

OR

02

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The design speed is the main factor on which geometric design elements depends.

OR The sight distance ,radius of horizontal curve ,super elevation ,extra Widening of pavement

,length of horizontal transition curve and the length of summit and valley curve are all

depends on design speed.

2)Sight Distance :-

The safe and efficient operation of vehicle on road depends ,among other factors on the

road length at which an obstruction if any becomes visible to the driver in the direction of

travel .

OR In other words the feasibility to see a head or the visibility is very important for safe vehicle

operation on a highway.

OR Sight Distance available from a point is the actual distance along the road surface, which a

driver from a specified height above the carriageway has visibility of Stationary or moving

objects.

OR Sight distance is the length of road visible ahead to the driver at any instance.

.

02

e)List any four types of defects in CC roads.

i)The initial cost of concrete roads is high

ii)They required skilled supervision and labor for their construction

iii)They are liable to crack and warp due to temperature variations

iv) They become noisy under iron tired traffic.

v) They are less resilient than bituminous or W.B.M. roads.

vi)They may cause glare due to reflected sun light.

vii)They required long time for their curing and thus they cannot be opened to traffic earlier

viii) It is very difficult located repaired sewers and water mains laying under the pavement

in their case

01

Mark

for

each

( any

four )

f)State necessity of road maintenance.

i) It is important to maintain road properly. Timely and correct maintenance of the

road helps in preventing the accidents

ii) If drains are not maintained, water may start flowing on the road, rendering the road

slippery. The shoulders get eroded, decreasing the width of roads on curve.

iii) Also maintenance increases the life of the pavement, making the cost of road

economically viable in the longer run .

iv) Various types of failures in the pavement ranging from minor and localize to major

and general failure takes place on the road.

01

Mark

for

each

Q6) Attempt any four of the following 16

a) State causes of road accidents.

1)Due to Pedestrians traffic – i) Carelessness of people.

ii) Due to crossing of road at other places than the cross- walks.

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2) Due to Passengers :-

i) On the road passenger create trouble to the driver.

ii) Passengers making noise , jocking and carelessly drive.

3) Due to Vehicle :-

i) At the night head light are not provided properly.

ii) When suddenly break failure are occurs.

4) Road conditions :-

i) When maximum curves are provided

ii) When wrong super elevation are provided.

01

mark

for

each

b)Draw neat Sketch of clover leaf patterns fly over.

03

Mark

for neat

sketch

01

Mark

for

directio

n

arrows

c)Draw signs for :-

01

Mark

for

each

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d)State necessity of traffic volume study.

Traffic volume study:- The survey of the number of vehicle and pedestrian crossing a

section of road per unit time during any selected period is called traffic volume study.This

study can be carried out for vehicles and pedestrians separately or combined. It is done at

number of selected points along the road. These selected points are known as count posts or

traffic count stations. The location of the traffic count stations should be decided by

dividing every road in to convenient sections, each carrying approximately similar traffic.

This study may be carried out one or twice a year during session of peak traffic depending

up on the importance of the road. In cities the peak traffic is at the starting and end of office

timing.

04

Mark

e)State Different type of traffic Control devices with sketch.

1)Traffic control device :-

I) The various aids and devices used to control, regulate and guide traffic may be called as

traffic control devices.

II) The General requirement of traffic control devices are attention, meaning, time for

response and respect of road users.

The following are the traffic control devices are follows :-

a)Traffic Signs:-

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I) Warning Sign :-

II) informatory Sign:-

b)Markings :-

I) Kerb Marking. II) Carriageway markings.

III)Object marking IV) Reflector marking

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c)Signals :-

The signals are classified into the following types:-

1) Traffic control Signals.

I)Fixed - time Signals II)manually operated Signals

III) Traffic actuated (automatic signals)

2)pedestrian signals:-

3)Special Traffic Signal

d)Traffic Island:-

01

01

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01

f) State Objects of planting tree along Road Sides .

Objects of planting tree along Road Sides are Follows:-

1. Trees are remove Co2 to create a carbon sink.

2. Trees provide significant low-Carbon option for building and energy.

3. Tree Transform our built Environment.

4.Tree increase resilience to climate change

5. Tree make a significant Environmental Contributio

01

Mark

for

each.

(any

four)