Safety Benefits of Implementing Adaptive Signal Control Technology: Survey Results

Abstract

The safety benefits and costs associated with implementing adaptive signal control technology (ASCT) were evaluated in this study. A user-friendly online survey was distributed to 62 agencies that had implemented ASCT in the United States. Twenty-two agencies responded to the survey, providing information about the system type, detection type, and cost of ASCT implementation. These agencies were from city governments (47%), state governments (29%), and county governments (24%). They represented both a wide range of ASCT implementation rates (from 1 to 700 intersections) and five of the most popular ASCT systems. There was a range of ASCT costs for different systems and detection types used with the system. The average cost per intersection to the agencies that responded was $38,223 when cost data from all agencies were included, but it was$28,725 when the cost data from agencies with the lowest and highest figures were excluded. Detailed volume and geometry data were provided by the respondents for six specific intersections. Crash data were provided for three of these six intersections. Each of the three intersections exhibited a crash reduction, but the sample size was too small for statistical testing. The observed ASCT cost per intersection per annual crash reduction was computed for the three intersections, and it ranged from $5,444 to$37,500. The scope of this study was very limited; thus, only very limited conclusions could be drawn. The limited data seem to indicate that there are safety benefits for implementing ASCT. It is recommended that a controlled experiment of ASCT implementation in Illinois be conducted to determine benefit–cost ratios and compute a crash modification factor (CMF).Illinois Department of Transportation R27-SP20published or submitted for publicationnot peer reviewe