ABSTRACT
The influence of stopped delay on driver gap acceptance behaviour is investigated. Gap rejection/acceptance data collected for minor road drivers executing left-turning manoeuvres at two separate priority intersections are analysed. The mean critical gapfit (C) and its variance (O2) are separately estimated from the aggregated data and from abstractions of the data based on the durations of stopped delay. It has been found that at shorter durations of stopped delay by minor road drivers, the mean critical gaps obtained are higher than those obtained when minor road drivers experience higher durations of delay. A statistical comparison shows that at the %% level of significance, the mean critical gaps estimated from the disaggregated data are significantly different from the value obtained from the aggregated data, the values being in reasonable agreement when the mean delay to minor road drivers is about 30s. The practical significance of these differences in mean critical gaps as reflected in the computed values of the minor road capacity is also investigated. It has been found that the minor road capacity will be slightly underestimated during periods when minor road drivers experience high durations of stopped delay and seriously over-estimated at situations when durations of stopped delay are short. Empirical equations have been derived relating the mean critical gap to the mean delay, average main flow and the minor road capacity.