This study examined the safety effectiveness of Sydney Coordinated Adaptive Traffic Systems (SCATS) on a six mile segment of M-59 in the northern metropolitan area of Detroit, Michigan. In addition to a before and after analysis, researchers compared performance on M-59 to a similar corridor (Dixie Highway) having only pre-timed signal control.

SCATS was initially deployed at 28 intersections and then expanded through Oakland County's traffic control system, Faster and Safer Travel through Traffic Routing and Advanced Controls (FAST-TRAC). The design was intended to use roadside video cameras, computers, and communication networks to monitor traffic conditions and automatically adjust signal timing as needed to reduce vehicle stops, decrease delay, and improve traffic flow. After the initial deployment, engineers continued to fine tune SCATS to improve traffic conditions and increase safety.

In 2007, a study was conducted on M-59 to evaluate the performance of SCATS in terms of mobility benefits. Initial results showed that after the system was initially installed the number of vehicle stops on the corridor decreased significantly. Benefits for other measures, however, were marginal. To gain a better understanding of the impacts on safety, researchers conducted additional analysis on the following crash data.

• Crash data of 1999-2001 (before period) and 2003-2008 (after period) on M-59.
• Crash data of Dixie Highway (pre-timed corridor) and M-59 (SCATS corridor) during 2003-2008.

FINDINGS