USING A DRIVING SIMULATOR TO ASSESS THE SAFETY BENEFITS OF VARIABLE SPEED LIMITS

In this study the authors assess the driver's reaction and acceptance of VSL (Variable Speed Limits) and VMS (Variable Message Signs) using a driving simulator, where the VMS alerts the driver about the upcoming VSL. Although it has already been proved the positive safety benefits of VSL (Abdel-Aty et al., 2006) using a microscopic traffic simulation; there is a need to evaluate in detail the driver's behavior under the presence of VSL or VMS. An experiment testing different VSLs and VMSs was designed and carried out at UCF (University of Central Florida) using subjects from 5 different age and 2 gender groups. Twenty four different scenarios were designed with three different levels of information displayed on the VMS and different VSL strategies. The base scenario, no VMS and no VLS, is included in the 24 scenarios. The VSL strategies included different levels of speed reduction, both gradually and abruptly. The scenarios were designed based on the recommendations made by Abdel-Aty et al. (2006), which includes a decrease of speed limit upstream and an increase of speed limit downstream and tests a successful implementation strategy that was observed using the microscopic traffic simulator. In addition, two levels of traffic were also included in the scenarios. The results indicated that VMS coupled with VSL produces the best results. It also showed age differences in the reaction to speed changes.