What is defined as the capacity of an intersection approach?

• A. Hourly volume with 100% green time
• B. Maximum traffic flow in one phase
• C. Hourly volume less than full green time
• D. Clearance time for pedestrian crossings

Answer: (C)

The capacity of an intersection approach is best defined as the maximum flow of traffic that can pass through the intersection in a given time period, considering factors such as traffic signal timing and vehicle characteristics. This understanding encompasses the context of traffic flow dynamics.

Answer choice concerning hourly volume less than full green time reflects the practical aspect of what an intersection can accommodate during its operational phases. In real-world scenarios, intersections rarely experience full green time consistently due to various influencing factors, including traffic signal cycles, congestion, and clearance times. Therefore, the capacity is typically assessed based on the realistic flow that can be expected to occur, which is often less than what would theoretically be achieved if all available green time was granted without interruptions.

The other interpretations, though they describe certain aspects of traffic operations, do not accurately capture the definition of capacity as it pertains to the operational limits of intersection approaches. For instance, maximum traffic flow in one phase addresses only a part of the broader dynamic involved, while hourly volume with 100% green time misrepresents the reality of intersection usage. Clearance time for pedestrian crossings focuses specifically on pedestrian dynamics and does not relate to vehicle flow capacity at all. Therefore, the definition around volume less than full green time encompasses a more realistic and applicable understanding of