Which of the following is known as design capacity ?

Answer: Option D

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.