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. 

Second 20 Year Plan focused on developing highway infrastructure in India.

• The plan aimed to provide 1600 km of expressways as part of the proposed national highway system.
• This initiative was designed to enhance connectivity and support economic growth.
• It included strategies for the efficient use of existing transport networks.
• Significantly, the plan allowed for the detection of railway track lengths when calculating road lengths.

This comprehensive approach aimed to ensure that road development met the needs of urban and rural areas alike.

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.

City roads that provide access to residences, businesses, and other buildings are categorised into different types based on their function.

• Arterial streets: Major routes designed for high traffic volumes and long-distance travel.
• Sub-arterial streets: Secondary routes that connect arterial streets, accommodating moderate traffic.
• Collector streets: Streets that gather traffic from local streets and direct it to arterial roads.
• Local streets: Roads primarily serving residential areas, designed for lower traffic volumes.

Among these, the sub-arterial street plays a critical role in connecting neighbourhoods and facilitating access to various local amenities.

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.

The principle of road alignment considers several factors to ensure that the road is efficient, safe, and economically viable.
Here's why each statement is correct:

• B: Its gradient should be easy: The gradient of the road should not be too steep to ensure safe driving conditions and to reduce wear and tear on vehicles. It should be smooth and manageable.

• C: It should aim at avoiding deep cuttings and fillings: Deep cuttings (digging into the earth) and fillings (piling earth) can be expensive and environmentally disruptive. Road alignment aims to minimize these, as they add to the cost and environmental impact of the project.

• D: It should be straight: While roads do not need to be entirely straight, the principle of alignment aims to keep the road as straight as possible within the constraints of the terrain to minimize travel distance and ensure smoother driving conditions.

Thus, A: all the below is the correct choice, as it encompasses all the principles of good road alignment.

The sequence of surveys in a road project is as follows:

• Topographic survey: This involves mapping the physical features of the land, including elevations, contours, and existing structures. It provides essential data for design.

• Reconnaissance survey: A preliminary assessment of the area. It helps identify the best routes and any potential challenges or obstacles.

• Preliminary survey: A more detailed examination of the chosen route. This includes gathering data on soil conditions, hydrology, and environmental impacts.

• Detailed survey: The final and most precise survey. It focuses on specific design requirements and incorporates all relevant data for construction plans.

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.

In the final survey, the center line stakes are typically driven at an interval of 50 meters in plain terrain for detailed and accurate surveying. This interval helps in providing sufficient control points for measurements and ensuring the alignment of the project.

While other distances like 100m or more may be used in specific situations, 50 meters is the standard interval for staking in plain terrain.

In hilly terrain, the distance between centre line stakes is crucial for accurate surveying. The recommended intervals for driving these stakes are as follows:

• 10 m - Suitable for very detailed work in steep areas.
• 20 m - A good balance for moderate detail and accuracy.
• 30 m - Useful for less complex terrains.
• 50 m - Ideal for flatter, less detailed surveys.

Choosing the right interval depends on the specific requirements of the survey and the terrain features.

Longitudinal & Cross-sectional Profile→

Plain Terrain:100-200m

Rolling Terrain:50m

Hilly Terrain:30m

The final report on a road project should include the following key components:

• Land acquiescence plan: This outlines the agreements and permissions regarding land use.

• Cross-drainage details: Essential for managing water flow and preventing flooding on the road.

• Plans of quarries: Information about the sources of materials for the project, including location and capacity.

Each of these elements is crucial for ensuring the project is viable and sustainable.

Ascending order according to width:

• Carriageway - This is the main part of the road where vehicles travel.
• Formation width - This refers to the total width of the road structure, including the carriageway and shoulders.
• Right of way - This is the legal right to pass through or over a property or area, typically wider than the carriageway.

The correct order, from the narrowest to the widest, is:

• Carriageway
• Formation width
• Right of way

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 portion of the roadway between the outer edges of the carriageway and the drains in case of cuttings is known as:

• The shoulder is the area adjacent to the roadway.
• It provides space for vehicles to pull over safely.
• The shoulder enhances safety by accommodating breakdowns.
• It also assists in drainage by directing water away from the road.

Understanding the role of the shoulder is essential for road design and maintenance.

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.

The base course of a road is crucial for ensuring stability and durability. It typically consists of:

• Gravel: A mixture of rock fragments that provides drainage.
• Sand: Helps with compaction and stability.
• Silt: Fills voids between larger particles, enhancing the mix.
• Stabilised soil: Soil treated to improve its strength and durability.
• Selected granular soil: Carefully chosen soil types that meet specific engineering requirements.
• Broken stone aggregates: Crushed stone that offers resistance to deformation.

These materials are often combined to create a strong and stable base layer, which is essential for supporting the overlying layers of the road. The choice of materials depends on factors such as local availability, cost, and the expected load on the road.

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