Evaluation of Traffic Signal Installations

To signalize an intersection, certain warrants need to be met. A series of such warrants have been developed since the 1920's and most of them deal with vehicular flows. Currently, eight warrants exist that govern the installation of a traffic signal and these warrants reflect current thinking and views regarding traffic flows and intersection safety. However, these warrants do not account for site specific traffic patterns, geometric alignments or safety issues that may affect the operational and safety performance of the intersection. Previous studies have shown that traffic signals can cause more problems than their intended goals--they stop traffic unnecessarily, increase delays and pollution levels, and may compromise safety. Crash severity and type, exposure levels, geometric features, and other trash related features need to be addressed to more accurately describe the implications from a traffic signal installation.