Quantifying Effectiveness and Impacts of Digital Message Signs on Traffic Flow

Digital message signs (DMS) are a vital part of the advanced traveler information systems (ATIS) that disseminate various real-time travel information to the road users, including traffic diversion, travel time, congestion, upcoming roadwork, lane closures, and incidents such as accidents. Other information includes inclement weather, speed regulations, special events, and safety related messages such as seatbelt usage campaigns. Although many state DOT guidelines (including Michigan) closely follow the Federal Highway Administration (FHWA)’s Changeable Message Sign Operation and Messaging Handbook, there exist a number of DMS operational practices that are unique to different states. With a limited budget and resources, it is important for the Michigan Department of Transportation (MDOT) to evaluate its current practices in order to invest only on DMS practices that have proved to be highly effective. Therefore, this research intended to develop a data driven methodology to assess the effectiveness of different DMS, message types and installation location in Michigan. The study also generated results to facilitate better allocation of MDOT’s resources by investing in effective sign technologies for traffic improvement, and improve overall DMS operational practices in the state of Michigan. This report is available from the Michigan DOT web site at https://www.michigan.gov/MDOT/-/Media/Project/Websites/MDOT/Programs/Research-Administration/Final-Reports/SPR-1709-Report.pdf