What is average queue length used for in arterial signal design?

What is average queue length used for in arterial signal design?

• A. To set the number of lanes.
• B. To determine the color of pedestrian crossing lights.
• C. To schedule maintenance windows.
• D. To estimate the impact of red times on throughput and safety.

Answer: (D)

Average queue length measures how many vehicles are waiting on an approach during red, and that helps quantify how much service is lost each cycle. In arterial signal design, this metric is used to gauge the effect of red times on both throughput and safety. If the average queue grows long, fewer vehicles pass per cycle, lowering overall throughput, and the long queues can create safety issues such as rear-end crashes or blocking downstream intersections and pedestrian crossings. By evaluating queue length, designers adjust timing parameters (cycle length, green splits, offsets) to keep queues reasonable, maintain efficient flow, and reduce safety risks. This is why it’s used to estimate the impact of red times on throughput and safety.

Average queue length measures how many vehicles are waiting on an approach during red, and that helps quantify how much service is lost each cycle. In arterial signal design, this metric is used to gauge the effect of red times on both throughput and safety. If the average queue grows long, fewer vehicles pass per cycle, lowering overall throughput, and the long queues can create safety issues such as rear-end crashes or blocking downstream intersections and pedestrian crossings. By evaluating queue length, designers adjust timing parameters (cycle length, green splits, offsets) to keep queues reasonable, maintain efficient flow, and reduce safety risks. This is why it’s used to estimate the impact of red times on throughput and safety.