Risk Evaluation for In-vehicle Sign Information

The goal of the study was to examine the influence of in-vehicle signing (IVS) pertaining to four types of changing driving conditions and determine the utility and potential safety costs associated with the IVS information. Signage displayed on a personal navigation device was presented for specific zones within the simulation to assist drivers' preparation for transitioning to new driving conditions ahead. These zones included: speed zone changes within the same roadway, notification of school zones, notification of work zones, and notification of curves. Driving performance measures known to be related to distraction as well as subjective usability and workload measures were used to help identify potential distraction associated with the IVS information. Moreover, risk analysis was conducted to evaluate the safety associated with IVS technology compared to the known safety levels with standard roadside signage. The objective measures collected in this study (both driving performance and risk analysis) indicated that implementing IVS technology would impact driving performance in the following manner:  When IVS was deployed in the absence of external signs, speeding behavior significantly increased relative to baseline levels. IVS technology was not observed to impact speeding behavior when external signs were also present.  Risk analysis suggested that IVS technology (when used in conjunction with external signs) can improve the safety associated with frontal-impact crashes; however, risk analysis proved that safety across all crash types was significantly reduced below baseline levels when IVS was used without external signs. Moreover, subjective usability results reinforced the driving performance findings.