Evaluation of Dynamic Message Signs on Rural Freeways: Case Study of a Full Freeway Closure

Abstract

The evaluation of dynamic message signs (DMSs) has been challenging to undertake because of the difficulty of identifying the effects of DMSs from traffic patterns. The primary contribution of this study is the comprehensive evaluation of DMSs in a rural area during a full freeway closure by using field data, driver surveys, and simulation. A full freeway closure scenario offers an opportunity to identify the effects of DMSs, because there is a network-wide shift in traffic demand from the closed route to the alternate route(s). A unique data collection and analysis approach was used to capture regional traffic patterns, including the processing of all traffic movements from four full interchanges. A significant increase in traffic flow on the detour route and a corresponding decrease on the affected route were observed during the freeway closure. Simulation was used to isolate the benefits of DMSs from other traveler information modes such as newspaper, TV, and radio, and to explore the sensitivity of the network to different levels of driver compliance. Depending on the proportion of drivers who chose to divert based on DMSs, monetary benefits were estimated to range between US$2,394 and $65,643 for the three-day freeway closure. Driver surveys conducted during the freeway closure revealed that 57% of the drivers utilized DMS information and 41% of drivers relied solely on DMSs to obtain information related to the closure and the detour route.