Variable Speed Limit System: Development, Demonstration, and Evaluation
Investigators:	Richard Lyles and William Taylor, Department of Civil and Environmental Engineering
Partners:	Michigan State University, Michigan Department of Transportation, International Road Dynamics

Funded by the Federal Highway Administration, the development, demonstration, and evaluation of a variable speed limit system embodies a marriage of developing intelligent transportation system (ITS) technology with traditional concerns of traffic control device effectiveness and work zone safety. A product of a public-private partnership, the system is designed to monitor work zone traffic and environmental conditions in real time and adjust the speed limit according to algorithms that vary according to factors such as worker presence. The goals for the system include: more reasonable speed limits, more uniform flow, and reduced travel time.

The prototype system consists of seven trailers which can either operate independently or based on conditions observed up- or downstream (at other trailers in the system). Each trailer has a changeable-message speed-limit sign; an on-board microprocessor to control collection, processing, and transmittal of data; and sensors for monitoring traffic flow in the adjacent lane. One trailer also has a sensor for changing climatic conditions which can also be factored into the speed limit algorithm. The system can be controlled on-site or through a remote dial-up.

The system was deployed during the 2002 construction season on I-96 in the Lansing area with another deployment planned in Spring 2003.