Behavior of two-wheelers at limited priority uncontrolled T-intersections

• We analyzed and modeled gap acceptance behavior of two-wheelers in India.
• The right turning movements at uncontrolled T-intersections are considered.
• Critical gap for major road by different methods vary from 2.378 to 3.06 s.
• Critical gap for minor road vary from 2.77 to 3.71 s.
• Maximum likelihood method is found to give more consistent results.

Being convenient and affordable, motorized two-wheeler is the most widely used personal mode for short and medium distance trips in India, thereby resulting in a very high concentration of two-wheelers on Indian roads. Its compact size and aggressive nature of two-wheeler riders have significant impact on the overall traffic characteristics and safety. A large number of unsignalized intersections in India do not have stop or yield sign, and even if it exists, drivers in general do not follow the intended priorities. The combinations of these factors create complex conditions at unsignalized intersections. At some intersections, where the drivers clearly perceive major and minor roads, priority rules are followed to a certain extent. Such partially controlled intersections where limited priorities are observed are studied here. The focus of this paper is on analyzing and modeling gap acceptance behavior of two-wheelers at limited priority unsignalized T-intersections in India. The data collected at four intersections revealed that accepted gaps/lags follow lognormal distribution. Logit models are developed for major and minor road right turnings which show that the probability of accepting a gap is higher if the driver is young, the conflicting vehicle is a two-wheeler, or both. Critical gap values are estimated using Raff's method, lag method, Ashworth's method, logit method, and maximum likelihood method. These values vary from 2.38 to 3.06 s for major road right turning and 2.77 to 3.71 s for minor road right turning. The maximum likelihood method is found to give the most consistent values. The findings of this study are useful in developing performance and safety evaluation of uncontrolled intersections in India.