AN EVALUATION OF TRAFFIC CONTROL DEVICES AND DRIVER DISTRACTION ON DRIVER BEHAVIOR AT RAILWAY-HIGHWAY GRADE CROSSINGS

At-grade crossings (grade crossings) are those crossings in which any part of a roadway intersects with railroad tracks. Safety at these railroad-highway grade crossings is a major concern, with traffic control warning devices serving as the main mechanisms for improving safety. There are three factors that influence a driver’s behavior at a given crossing. First, traffic control devices, including warning devices at the railroad-highway grade crossings, provide the driver with information whose impact will depend in part on the likelihood that the driver knows whether to glance in the direction of the device based on prior experience, and in part on what the driver understands the warning device to mean. Second, assuming that the driver identifies the warning, the driver’s prior knowledge influences his or her expectancy regarding various railroad-highway grade crossing situations and, therefore, the way in which the driver responds to the hazard presented by the crossing. Finally, the driver’s own physiological (e.g., impaired) and psychological (e.g., distracted) state will modify the role that conspicuity and expectancy have on the driver’s behavior. This dissertation centers on the impact of distraction and the effect of traffic control and warning devices have on stopping behavior and glance behaviors at non-gated railroad-highway grade crossings and studies a possible countermeasure which when combined with traffic control and warning devices can mitigate the effects of distraction due to less than optimal glance patterns. Two driving simulator experiments were conducted that arguably targeted the most critical need, in particular the need to identify the role that distraction has on the effectiveness of traffic control and warning devices at grade crossings. Ninety-nine participants were evaluated across two driving simulator experiments. For the first experiment, the role distraction plays in reducing the benefit of crossbuck and flashing lights was analyzed. Participants either engaged in a distracting task or did not engage. The secondary tasks included a mock cell phone conversation or an in-vehicle task where the participant driver was asked to change the radio station. The first experiment showed participants in all groups had trouble navigating the grade crossing environment thus pointing to the need to evaluate supplementary treatments which may benefit driver behavior at these crossings. The second simulator experiment evaluated the impact of the dynamic envelope pavement markings on driver glance pattern and behavior as they approached grade crossings while drivers also performed a distracting or non-distracting task. Results show that the addition of these markings can alert drivers of the presence of a grade crossing with anticipation, and as a result induce drivers to glance more and potentially stop in higher proportions than when the markings are not present