How driver risk perception affects operating speeds

Excessive speed is one of the primary safety hazards facing highway users. However, in many cases operating speeds exceed design speeds, and drivers generally ignore posted speed limits. The main objective of this research was to identify roadway elements and roadside features that could influence driver operating speeds in rural two-lane roads without compromising safety. Virtual Reality video simulations were employed and drivers recorded the influence of these elements on their judgments about the appropriate driving speed. The driver/participants viewed 22 models projected on a large screen in a darkened room, simulating the windshield of a vehicle. The viewing sessions simultaneously accommodated significant numbers of subjects and gathered their feedback through electronic audience response systems. The response feedback was modeled through use of a fuzzy set system allowing the inspection of interrelationships of many different design parameters. The arithmetic mean score for discomfort for each scenario ranged from 4.3 to 8.1, representing large variation among scenarios. Our results show that simulating the driving environment using visualization was effective in generating feedback, thus avoiding the expensive and time-consuming process of individually 'processing' subjects through a driving simulator.