One approach of an intersection with fixed time traffic signals, vehicles arrive at 500 veh/h on the approach. The cycle time of the intersection is 80 seconds, and the effective green time for the approach is 24 seconds. The saturation flow of this approach is 2000 veh/h. Find out solutions for the following situations with the assistance of a Time-Flow Diagram.

(a) How many seconds of green time should be extended to the current level to achieve a no delay condition if there are delays, or how many extra vehicles could pass through the intersection if there is surplus green time?

(b) Due to a traffic incident, the saturation flow of this approach is reduced by 30 per cent. Is there any delay under the new situation? How many vehicles may experience delay?