Impacts of Signal Cycle Lengths on Delay, Fuel Consumption, and Emission: Case Study of Khok Nao Intersection, Songkhla Province

Abstract

Signal cycle length of the intersection in several urban areas has been set to be a long cycle time which is inconsistent with the traffic volume in each period of the day. The long cycle length often leads to the travel delay, fuel consumption and pollutant emissions. This paper presents the effects of different cycle lengths on travel delay, fuel consumption, CO₂ emission and economic losses. The Khok Nao intersection, Hat Yai District, Songkhla Province was selected as a case study. The results showed that the cycle lengths longer than 120 seconds (i.e., 150, 180, 210, and 240 seconds) dramatically increase the economic losses by 19%, 31%, 43%, and 51%, respectively. On the other hand, if the cycle length lower than 120 seconds is set corresponding to the traffic volume (90 seconds), it could significantly reduce the economic loss by 28%. The results of this study can be used as a guideline in determining the appropriate cycle length setting for the concerned authorities.