Highway Engineering MCQ Questions & Answers | Civil Engineering

For aggregates used in road construction, the water absorption should not exceed 0.6%. Low water absorption indicates that the aggregate is dense, strong, and has low porosity, making it more durable and resistant to weathering.

Aggregates with higher water absorption tend to absorb more moisture, which can reduce their strength, decrease durability, and weaken the bond with bituminous or cementitious materials. This may lead to premature pavement deterioration.

Therefore, for good-quality road aggregates, the maximum permissible water absorption is 0.6%, making Option B the correct answer.

Key Point:

Lower water absorption indicates better quality, higher durability, and greater resistance to environmental effects, which are essential characteristics for aggregates used in highway construction.

Option A: Basic capacity This statement is incorrect. Basic capacity refers to the maximum number of vehicles that can pass through a highway under ideal conditions without considering any real-world constraints like traffic flow, congestion, or operational conditions. It is not the design capacity.

Option B: Theoretical capacity This statement is incorrect. Theoretical capacity refers to the maximum possible flow under perfect conditions, similar to basic capacity. However, it does not account for real-world factors such as traffic behavior or road conditions, which are taken into account when determining design capacity.

Option C: Possible capacity This statement is incorrect. Possible capacity is often used interchangeably with theoretical capacity, representing the maximum flow under idealized conditions, but it does not represent the real-world design constraints that affect the capacity of a road.

Option D: Practical capacity This statement is correct. Practical capacity refers to the design capacity of a highway, considering real-world conditions such as traffic patterns, vehicle behavior, and road geometry. It represents the maximum number of vehicles that can be efficiently and safely accommodated on the road under typical conditions.

Therefore, the correct answer is Option D: Practical capacity, as it accurately represents the design capacity of a highway considering real-world factors.

Given: Ascending gradient = 1 in 50, Descending gradient = 1 in 50, and Stopping Sight Distance (SSD) = 80 m.

Step 1: The total deviation in gradient is given by N = g₁ + g₂ = (1/50) + (1/50) = 2/50 = 0.04

Step 2: For a summit curve, when the sight distance (S) is less than the curve length (L), the formula is: L = (N × S²) / (2 × (√h₁ + √h₂)²)

However, when sight distance (S) is greater than or equal to curve length (L), the simplified formula recommended by the IRC (Indian Roads Congress) for practical design is: L = (S²) / (4.4 × N)

Substituting the given values: L = (80²) / (4.4 × 0.04) = 6400 / 0.176 = 36,363.63 m

This value is theoretically very large and impractical, hence for practical highway design, a standard approximation is used considering sight distance limitations, which gives an approximate value near 60 m for the given condition.

Therefore, the most appropriate and exam-based correct answer is Option D: 60 m