ASSESSING AND MITIGATING THE IMPACTS OF DYNAMIC MESSAGE SIGNS ON HIGHWAY TRAFFIC

Abstract

As a critical component in Intelligent Transportation Systems (ITS) of modern traffic management, dynamic message signs (DMS) are widely used in many countries as an effective means to provide motorists with up-to-date information regarding accidents, congestion, road conditions and travel time, etc. However, it was observed in traffic data that motorists tended to slow down when approaching active DMSs and speed up after passing these signs. The speed variations could pose safety hazards to other motorists on highways. To gain insights into this issue and understand associated causes and risks, a human factors study was conducted to help ease the speed variation when approaching DMSs. The effect of DMS messages on traffic approaching and passing the signs were assessed by analyzing highway traffic data near DMSs. A questionnaire survey was conducted to identify associated causes and risks. Participants were further surveyed about their preferences on DMS characteristics such as message category, message type, number of frames, message details, and the use of graphics. Individual drivers' responses to various DMS designs were evaluated through a simulation test. This study has provided updated knowledge regarding the effects of DMSs on highway traffic and has identified measures to improve the design and display of DMS messages to help ease the speed variation of approaching traffic.