No abstract

A Type II dilemma zone (DZ) is the segment of roadway on the approach to an intersection at which drivers have difficulty deciding whether to stop or proceed at the onset of the circular yellow (CY) indication. The safety of signalized intersections is improved when DZs are correctly identified and steps are taken to reduce the likelihood that vehicles will be caught in such zones. This research purports that using driving simulators as a means of collecting driver response data at the onset of the CY indication is a valid methodology for augmenting analysis of decisions and reactions made within the DZ. The data obtained were compared with data from previous experiments documented in the literature, and the evidence suggested that driving simulation was valid for describing driver behavior under the given conditions. After the data were validated, fuzzy logic was proposed as a tool for modeling driver behavior in the DZ, and three models were developed to describe driver behavior as it relates to the speed and position of the vehicle. These models were shown to be consistent with previous research on this subject and were able to predict driver behavior with up to 90% accuracy.

Summary: A novel procedure was developed and validated for the accurate observation of naturalistic driver gap acceptance behavior at unsignalized intersections. Specifically, two-way stop-controlled intersections with a two way left turn lane (TWLTL) on the major road were examined. Three intersections were included as experimental locations. A sample size was collected of approximately 875 minor street vehicles which were exposed to over 2400 individual gaps. Characteristics such as gender, approximate age, vehicle type, presence of a queue behind the lead vehicle, and presence of passengers in the vehicle were collected as a function of the time of day (TOD). This work provides updated measures for the accepted gap as TOD varies, as well as exploring how accepted gaps are related to the wait time of a vehicle at the stop line.