Test: Highway Transportation- 1 - Civil Engineering (CE) MCQ

Correct Answer :- a

Explanation : In 1927 Jayakar committee for Indian road development was appointed. The major recommendations and the resulting implementations were :

 This paved the way for the establishment of a semi-official technical body called Indian Road Congress (IRC) in 1934.

The Indian Roads Congress (IRC) is the Apex Body of Highway Engineers in the country. The IRC was set up in December, 1934 on the recommendations of the Indian Road Development Committee best known as Jayakar Committee set up by the Govt. of India with the objective of Road Development in India. 

The urban roads mostly in cities and towns are congested during morning and evening times due to the school, college and office timings.

The Nagpur Plan divided the District Roads into two classes and the District Roads were defined as roads traversing each district, serving areas of production and markets and connecting these with each other or with highways and railways.

The state highways are usually roads that link important cities, towns, district headquarters, tourist centres and minor ports within the state, and connect them with National Highways or highways of neighboring states. These highways provide connections to industries or places from key areas in the state, making them more accessible.

The branch of engineering that deals with improvement of traffic performance, traffic studies and traffic network is called as traffic engineering, it also includes geometric design and other specifications.

Correct Answer :- a

Explanation : The main objectives of the preliminary surveys are:

 To survey the various alternate alignments proposed after the reconnaissance and to collect all the necessary physical information and details of topography, drainage and soil.

All geographical and other man made features along the traverse and for a certain width on either side surveyed and plotted.

Longitudinal & Cross-sectional Profile→

Plain Terrain:100-200m

Rolling Terrain:50m

Hilly Terrain:30m

Vertical curve:

Vertical alignment is the elevation of the centerline of the road. It may be in the form of a circular arc or a parabola

The common practice has been to use parabolic curves in summit curves. Parabolic curves with it can be laid out with ease as well as allowing a comfortable transition from one gradient to another. Hence statement I is true.

Although a circular curve offers equal sight distance at every point on the curve, for very small deviation angles a circular curve. and parabolic curves are almost congruent.

In valley curves the centrifugal force will be acting downwards along with the weight of the vehicle and hence impact to the vehicle will be more. It will result in jerking and cause discomfort to passengers. Hence comfort to passengers has to be considered in valley curves. Hence statement II is false.

The peak hour factor (PHF) is defined as.

Less PHF means that more congestion.

The minimum value of PHF is  and Maximum value is 1.

Given:

x = 15 minute.

Time Headway:- It is the time interval between the passes of the rear bumper of successive vehicles at a point.

• When the signal at an intersection turns green, the vehicles in the queue will start crossing the intersection. The first driver in the queue needs to observe and react to the signal change at the start of green time and the second driver does the same but only when he see the first vehicle moving.
• This results in a shorter headway than the first because the driver had an extra vehicle length to accelerate. This process carries through with all following vehicles where each vehicle’s headway will be slightly shorter than the preceding vehicle.
• This continues until a certain number of vehicles have crossed the intersection and start-up reaction and acceleration no longer affect the headways.
• The headway will remain constant beyond this point and this constant headway is known as the saturation headway. It generally occurs after the fourth or fifth vehicle passes the intersection.

Flow (q) = Density (k) × Velocity (V)

For Greenshields’s Model

Where,

V = Velocity at any instant

V_f = Free mean velocity

k = Density of the flow

k_j = Jam density of the flow

Maximum capacity (q_max) = V_max × K_max

As per Greenshields’s model

Maximum capacity ⇒ 

Road Camber height depends upon

1. Rainfall intensity in the area.
2. Type of the road surface whether it is flexible or rigid.
3. In case of flexible pavement, the recommended height of camber is 2 %. of the total width of the pavement.
4. For rigid pavement, the maximum recommended width is 1:72 .

P: d = 60t

Q: d = 60t²

Space Headway (S) = 60t² – 60t

For space headway to be max,

dsdt=0

120t – 60 = 0

⇒ 60(2t – 1) = 0

⇒ t = ½ hr

Maximum space Headway

= 60 × ½ - 60 × (½)²

= 60 × ½ - 60 × ¼

= 30 – 15 = 15 km