Overview
A driver approaching a signalized intersection where the light has turned yellow must make a decision whether to stop or proceed. A signal that is proper ly designed will provide an opportunity for a safe and legal maneuver. As approach speeds increase, how ever, it becomes more difficult to execute a safe maneuver. One countermeasure that is used to help provide advance warning to drivers of an approaching intersection or the impending signal cha nge at an approaching intersection is an advance warning signal (AWS) system. A number of AWS systems have been installed throughout the country. Four such systems were installed in the state of Utah in 2005. Since that time the effectiveness of these systems has been evaluated as a function of intersection safety. The metrics used for evaluation include crash data analysis, speed distribution analysis, and red-light running (RLR) analysis. The objective of this study is to evaluate and report the long-term e ffectiveness of the AWS systems installed in the state of Utah in June 2005, particularly at the intersection of Bangerter Highway and 13400 South. The results of the study indicate that overall the AWS sy stem has generally had a positive impact on the community, with positive results noted in all areas of an alysis. Given the nature of the study, however, it is difficult to quantify the extent of the overa ll impact as a function of only the AWS system.