Test: Highway Transportation- 2 - Civil Engineering (CE) MCQ

Thin bituminous surface 1÷40 = 0.025.
0.025 convert to %.
So 0.025*100 = 2.5%.

Thin bituminous surface 1÷40 = 0.025.
0.025 convert to %.
So 0.025*100 = 2.5%.

• Definition of Width of Formation: The width of formation refers to the total width of a road or path, including the roadway and any shoulders or drainage features.
• Importance of Width of Formation in Mountainous Areas: In mountainous areas, the width of formation is crucial for ensuring safe passage of vehicles, especially on narrow and winding roads.
• Considerations for Village Roads: Village roads in mountainous areas typically have limited space and may need to accommodate various types of traffic.
• Width Options: The options provided are 3.0 m, 4.0 m, 4.75 m, and 5.0 m.
• Selection of 3.0 m: Among the given options, a width of 3.0 m is most suitable for village roads in mountainous areas due to the following reasons:
  • Allows for safe passage of vehicles while minimizing the impact on the surrounding environment.
  • Provides enough space for single-lane traffic, which is common on village roads.
  • Helps to reduce construction costs and land acquisition requirements.
  • Balances the need for sufficient width with the constraints of mountainous terrain.

Minimum Right of Way for a Village Road

• Definition: Right of way refers to the legal right of a vehicle, pedestrian, or property owner to cross a specific piece of land. It is essential for the construction of roads to ensure safe passage.
• Importance: Having the minimum required right of way for a village road is crucial for ensuring smooth traffic flow, emergency vehicle access, and pedestrian safety.
• Factors to Consider: The minimum right of way required for a village road is determined by factors such as the volume of traffic, the width of the road, the presence of sidewalks, and future development plans.
• Standard Requirement: In an open area, the minimum right of way required for a village road is typically 15 meters. This width allows for two lanes of traffic, pedestrian sidewalks, and space for future expansion.
• Alternative Options: In some cases, local authorities may allow for a slightly reduced right of way, such as 12 meters, if certain conditions are met. However, it is always advisable to adhere to the standard requirement of 15 meters for optimal road safety and functionality.

Recommended Right of Way for Highways in Open Areas

• Definition: Right of way refers to the legal right of a driver or pedestrian to proceed first in a traffic situation.
• Importance: Proper right of way rules ensure traffic flows smoothly and safely.

Factors to Consider when Determining Right of Way

• Speed Limit: Higher speed limits may require a wider right of way to allow for safe merging and passing.
• Visibility: Areas with limited visibility may necessitate a wider right of way to allow for ample reaction time.
• Traffic Volume: Higher traffic volume may require a wider right of way to accommodate more vehicles.

Recommended Right of Way for Highways in Open Areas

• Option A: 50 m - This may be excessive for open areas and could lead to wasted space.
• Option B: 45 m - While a reasonable choice, there may be more optimal dimensions.
• Option C: 40 m - A narrower right of way may lead to congestion and safety issues.
• Option D: 30 m - This may be the most suitable option for highways in open areas, providing enough space for safe passage without unnecessary width.

Conclusion

• Based on the factors considered and the optimal balance between safety and efficiency, a recommended right of way for highways in open areas is 30 m.

Exceptional Gradient in Plains

• Definition: Exceptional gradient refers to the steepest incline that can be found in plains.
• Limited to: In plains, exceptional gradient is limited to a certain ratio of rise over run.

Options and Analysis

• Option A: 1 in 25 - This ratio indicates that for every 25 units of horizontal distance, there is 1 unit of vertical rise. This gradient is not considered exceptional in plains.
• Option B: 1 in 20 - This ratio indicates that for every 20 units of horizontal distance, there is 1 unit of vertical rise. This gradient is also not exceptional in plains.
• Option C: 1 in 15 - This ratio indicates that for every 15 units of horizontal distance, there is 1 unit of vertical rise. This is the correct answer as it represents an exceptional gradient in plains.
• Option D: None - This option implies that there is no exceptional gradient in plains, which is not accurate as there is a limit to the steepness of inclines in flat areas.

Conclusion

• Therefore, the exceptional gradient in plains is limited to a ratio of 1 in 15, making option C the correct answer.

In steep terrain ruling gradient is limited to. 1 in 25.

• Height of line of sight of driver: The height of the driver's line of sight is typically taken as 1.2 meters above the road surface. This is the height at which the driver's eyes are positioned when seated in the vehicle.
• Height of line of obstacle on road: The height of the obstacle on the road is usually taken as 0.15 meters. This is the height at which an obstacle or object on the road is positioned above the road surface.
• Stopping distance calculation: To calculate the stopping distance of a vehicle, the height of the driver's line of sight and the height of the obstacle on the road are important factors. These heights help determine the visibility of the obstacle to the driver and the time required for the driver to react and stop the vehicle safely.
• Relation to road safety: By considering the heights of the line of sight and the obstacle, road safety can be improved as it helps in determining the required stopping distance for a vehicle to avoid collisions or accidents.

Concept:

Stopping sight distance:

• At any spot having sufficient length to enable the driver to stop a vehicle traveling at design, Safety, without collision with any other obstruction.
• The stopping sight distance is the sum of the lag distance and the braking distance.
• Lag distance is the distance the vehicle traveled during the reaction time t and is given by vt, where v is the velocity in m∕sec2.
• Braking distance is the distance traveled by the vehicle during the braking operation.
   

​Hence, SSD = lag distance + braking distance and given by:

The main objective of a good transportation system is to provide safe economical, efficient transportation for the facility of passengers and the transport of goods.

IRC recommended the value of the coefficient of friction (f) as 0.35 for a design speed of 100 kmph.

• Speed of the overtaken vehicle = 40 kmph


• Speed of the overtaking vehicle = 60 kmph (assuming the overtaking vehicle is going at a safe speed)


• Relative speed = 60 - 40 = 20 kmph = 20 * 5/18 m/s = 50/9 m/s


• Time taken to overtake = Distance / Relative speed


• Distance = Relative speed * Time taken to overtake

• OSD = (Relative speed) * (Time taken to overtake)

• Time taken to overtake = Length of overtaken vehicle / Relative speed


• Assuming the length of the overtaken vehicle is 10 meters


• Time taken to overtake = 10 / (50/9) = 90/50 = 1.8 seconds

• OSD = (50/9) * 1.8 = 10 * 10 = 200 meters

• Initial Speed of the Overtaking Vehicle: 80 kmph


• Assuming the Speed of the Vehicle Being Overtaken: 0 kmph (as it is stationary for calculation purposes)


• Reaction Time: Assuming a reaction time of 2 seconds

• Reaction Distance = Initial Speed x Reaction Time


• Reaction Distance = 80 kmph x (2/3600) hr (converting seconds to hours)


• Reaction Distance = 0.444 m

• Overtaking Distance = (Initial Speed + Speed of Vehicle Being Overtaken) x Time to Overtake


• Time to Overtake = Overtaking Distance / (Initial Speed - Speed of Vehicle Being Overtaken)


• Time to Overtake = Overtaking Distance / (80 kmph - 0 kmph)


• Time to Overtake = Overtaking Distance / 80 kmph


• Time to Overtake = Overtaking Distance / (80 x 1000/3600) m/s (converting kmph to m/s)


• Time to Overtake = Overtaking Distance / 22.22 m/s


• Overtaking Distance = 22.22 x Time to Overtake


• Overtaking Distance = 22.22 x (2 + 5) s (Assuming 2 seconds reaction time and 5 seconds overtaking time)


• Overtaking Distance = 155.54 m

• Total Overtaking Sight Distance = Reaction Distance + Overtaking Distance


• Total Overtaking Sight Distance = 0.444 m + 155.54 m


• Total Overtaking Sight Distance = 155.984 m

• Intersection Sight Distance: Intersection sight distance is the minimum sight distance required at an intersection to ensure that drivers have sufficient visibility to make decisions safely.


• Approaching Vehicle Speed: The sight distance at an intersection should be enough to allow the approaching vehicle to change speed if necessary to avoid a collision.


• Stopped Vehicle Crossing: It should also be enough to enable a stopped vehicle to safely cross a main road without obstructing traffic or endangering themselves.


• Approaching Vehicle Stop: The sight distance should also allow the approaching vehicle enough time to stop if needed to avoid a collision.


• Optimal Value: The highest value of all these factors (approaching vehicle speed, stopped vehicle crossing, and approaching vehicle stop) should be considered to ensure the intersection sight distance is adequate for safe decision-making by drivers.

• Definition of Sight Distance: Sight distance is the length of roadway ahead visible to the driver.


• Importance of Sight Distance at Intersections: At intersections, sight distance is crucial for drivers to safely navigate through the crossing.


• Minimum Sight Distance Requirement: The minimum sight distance at an intersection along the minor road should be at least 40 meters.


• Reasoning for 40 Meters: This distance allows drivers on the minor road to have sufficient visibility of oncoming traffic on the major road to make safe decisions.


• Options Analysis:
  
  
  
  • Option A: 15 meters - This distance may not provide adequate time for drivers to react to approaching vehicles.
  
  
  • Option B: 30 meters - While better than 15 meters, this distance might still not offer enough time for safe maneuvering.
  
  
  • Option C: 40 meters - This is the recommended minimum sight distance for intersection safety.
  
  
  • Option D: 50 meters - While more than the minimum requirement, 40 meters is sufficient for safe intersection navigation.
  
  
  
  


• Correct Answer: Option C - 40 meters is the most appropriate choice for ensuring safe sight distance at the intersection.

• Design Speed: Given design speed of the main road is 100 kmph.


• Reaction Time: Assuming a conservative driver reaction time of 2.5 seconds.


• Braking Distance: Using the formula for braking distance - \(D = \frac{V^2}{254f}\), where V is speed in kmph and f is the coefficient of friction (assumed to be 0.4), we calculate the braking distance.


• Total Stopping Sight Distance (TSSD): TSSD is the sum of reaction distance and braking distance.


• Required Sight Distance at Intersection: Required sight distance at intersection should be at least equal to TSSD to ensure safe stopping in case of any unexpected event.

• Reaction Distance: \(V \times \text{Reaction Time} = 100 \times \frac{1000}{3600} \times 2.5 = 69.44 \text{ m}\)


• Braking Distance: \(D = \frac{100^2}{254 \times 0.4} = 98.43 \text{ m}\)


• Total Stopping Sight Distance (TSSD): \(69.44 + 98.43 = 167.87 \text{ m}\)

• The calculated total stopping sight distance at a design speed of 100 kmph is 167.87 m.


• Therefore, the required sight distance at the intersection should be at least 220 m to ensure safe stopping within the sight distance.


• Hence, the correct answer is option D: 220 m.

• Length of the vehicle: The length of a vehicle plays a crucial role in determining various design aspects related to driving and safety.


• Impact on overtaking distance: A longer vehicle will require more space for overtaking safely, as it will take longer to pass another vehicle on the road.


• Design considerations for gradient: The length of the vehicle can also impact how it handles gradients on the road, as longer vehicles may have different weight distribution and center of gravity.


• Camber adjustments: The camber of the road, which refers to the slope of the road surface, can also be influenced by the length of the vehicle and its design requirements.

Therefore, the length of a vehicle can have a significant impact on design considerations such as overtaking distance, gradient handling, and camber adjustments.

Explanation:
upto 10% : plain
between 10% and 25%: Rolling between 25% and 60% : mountaineous more than 60% : Steep.

Given ⇒ R = 120 m

f = 0.15

f= 0.24

Determination of the specific gravity

Where,

W₁, W₂, W₃, and W₄ are the percentage by weights of the coarse aggregate, fine aggregate, fines and bitumen respectively.

G₁, G₂, G₃, and G₄ are the specific gravity of the coarse aggregate, fine aggregate, fines and bitumen respectively.

Effective specific gravity of aggregates (coarse + fine) is given by

Where,

W1, and W2 are the percentage by weights of the coarse aggregate and fine aggregate respectively.

G1, and G2 are the specific gravity of the coarse aggregate and fine aggregate respectively.

Calculation:

Given,

W₁ = 55.0, W₂ = 35.8, W₃ = 3.7,and W₄ = 5.5

G1= 2.6, G2 = 2.7, G3 = 2.65 and G₄ = 1.01

Theoretical specific gravity

Effective specific gravity of aggregates (coarse + fine) is given by

∴ Theoretical specific gravity of the mix = G_t = 2.42 and the effective specific gravity of the aggregates = G' = 2.64

Concept-

• The fundamental relation between flow(q), density(k) and mean speed v is q = k x v

• When the density is zero, flow will also be zero, since there is no vehicles on the road.
• When the number of vehicles gradually increases the density as well as flow increases.
• When more and more vehicles are added, it reaches a situation where vehicles can't move. This is referred to as the jam density or the maximum density. At jam density,  flow will be zero because the vehicles are not moving.
• There will be some density between zero density and jam density, when the flow is maximum. The relationship is normally represented by a parabolic curve as shown in figure.

Given data and Analysis -

• At point S, speed is non zero but flow is zero, so density will be zero to get zero flow. So K_s will be minimum.
• At point P, speed is zero which means it is the jam condition so the density will be maximum.SO Kp will be maximum.
• So from point S to point P the density will increase gradually.
• So the correct order of density will be  k_P > k_Q > k_R > k_s.

Concept:

Where

V = Speed of the vehicle, e = super elevation, f = coefficient of lateral friction and R = radius of curve

Calculation:

Given:

V = 110 kmph, e = 8% = 0.08 and f = 0.10

R = 529.3 m

∴ The ruling design radius of the curve is 529.3 m

Given:

Initial weight of the vehicle (W₁) = 50 kN Final weight of the vehicle (W₂) = 100 kN Initial minimum skidding velocity (v₁) = v

When the weight of the vehicle is doubled (from 50 kN to 100 kN), the frictional force needed to maintain the same minimum skidding velocity (v) must also double to counteract the increased weight and maintain equilibrium.

The minimum skidding velocity (v₂) when the weight is doubled is therefore:

v₂ = v₁ * √(W₂ / W₁)

Substituting the given values:

v₂ = v * √(100 / 50) v₂ = v * √2

Therefore, the minimum velocity for skidding on a curve when the vehicle's weight is increased to 100 kN is:

v₂ = √2 * v

Concept:

Airport reference temperature =

Where, T_a = Average temperature of the hottest month

T_m = Monthly mean of the maximum daily temperature of the same month

Calculation:

Given:

T_m = 48°C, T_a = 39°C

∴ Airport reference temperature =

= 42°C