What does capacity measure in traffic engineering?

• A. The average speed of vehicles
• B. A qualitative assessment of traffic comfort
• C. A quantitative measure of traffic flow potential
• D. The maximum number of vehicles allowed on a road

Answer: (C)

Capacity in traffic engineering specifically refers to a quantitative measure of traffic flow potential. It represents the maximum number of vehicles that can pass a given point on a roadway within a specified time period under prevailing conditions. This measure is crucial in understanding how effectively a roadway can accommodate traffic demands, as it considers factors like lane width, roadway configuration, traffic control devices, and environmental conditions.

This understanding helps transportation engineers design and manage roadways to optimize safety and efficiency by ensuring that the volume of traffic does not exceed the road's capacity, which could lead to congestion and increased delays. While average speed, qualitative assessments of comfort, and maximum vehicle allowances on roads relate to traffic analysis, they do not encapsulate the concept of capacity as it pertains to the potential flow of traffic through a given point in a system.