IDLING AT AN INTERSECTION

^{1}and AMARJIT SINGH

^{2}

^{1}Petroleum Authority of Thailand , Bangkok, Thailand

^{2}Dept of Civil and Environmental Engineering, University of Hawaii at Manoa,

Honolulu, USA

The objective of this project is to find an optimal solution minimizing the number of vehicles idling at the Kapiolani-McCully intersection during the evening peak period (6 pm - 8 pm), by assigning appropriate traffic signal times for each direction. This duration would also take into account pedestrian safety constraints, set by the US Federal Highway Administration, i.e., that standard walking rates for pedestrians should be 4 feet per second for safe crosswalk countdown times. Signal times for four directions, i.e., McCully straight turn, McCully left turn, Kapiolani straight turn, and Kapiolani left turn, were determined using linear programming based on queue length, crosswalk countdown time, and vehicle arrival rates. Average vehicle arrival rates for each direction were measured to calculate the cumulative number of vehicles waiting. Since all vehicles in all directions can use the “right on red” rule for right turns without waiting for a green signal, the study focused on the number of vehicles waiting in the left-turn and straight-turn lanes. The study found that, in order to minimize the number of vehicles waiting under the constraints, a green-light time assigned for straight turns on McCully should be 23 seconds, a green-light time for straight turns on Kapiolani should be 20 seconds, and a green-light time of 9 seconds for all the left turns.