Abstract
This paper attempts to identify factors that may influence the gap acceptance behavior of drivers who turn left from the major road at unsignalized intersections. Drivers’ accepted and rejected gaps as well as their age and gender were collected at six unsignalized intersections with both two and four lanes on the major road, with and without the presence of a Left-Turn Lane (LTL), and with both high and low Speed Limits (SLs). Whether or not a driver accepts a given gap was considered as a binary decision and correlated logit models were used to estimate the probability of accepting a gap. Models with different factors were tested and the best model was selected by the quasi-likelihood information criterion. The gap duration, the number of rejected gaps, the mean and total time interval of the rejected gaps and the gender of the driver were all significant in explaining the variation of the gap acceptance probability, whereas the number of lanes of the major road, the presence of LTL, the SL and the driver’s age category were not. Gap acceptance probability functions were determined based on the best model, including both the factors of the number of rejected gaps and the mean time interval of the rejected gaps. As the values of these two factors increase, the probability of accepting a given gap rises up. The developed model can be further applied in practice to improve the analysis of traffic operations and capacity at unsignalized intersections.
Highlights
At two-way stop-controlled unsignalized intersections, traffic of lower priority must yield to traffic of higher priority
The base values of the critical gap and follow-up time for passenger cars are provided for all non-priority manoeuvres at an unsignalized intersection
This is reflected in the Probability models, where the number of lanes and the presence of the left-turn lane are both insignificant. This result is consistent with HCM, in which the same critical gap value is recommended for both two-lane and four-lane major streets and no differences are recorded between conditions with and without left-turn lanes (Highway Capacity Manual 2000)
Summary
At two-way stop-controlled unsignalized intersections, traffic of lower priority must yield to traffic of higher priority. Capacity analysis of unsignalized intersection is founded upon a clear understanding of the interactions between drivers with different levels of priority, of which gap acceptance theory is an important part. According to the Highway Capacity Manual (2000) – HCM, the critical gap is the minimum time interval between vehicles in a traffic stream that is acceptable for the driver to complete a conflicting maneuver. It is estimated by the maximum likelihood method assuming that drivers are homogeneous and consistent, i.e. they are expected to all behave the same way and will accept all gaps that are larger than the critical gap and reject all smaller gaps. Once the critical gap is determined according to the procedures in the HCM, Transport, 2017, 32(3): 252–261 the potential capacity of each minor traffic stream can be computed using the gap acceptance model: c= v ⋅
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
