Implementing the maximum likelihood methodology to measure a driver's critical gap

Most of the capacity calculation procedures for two-way stop-controlled (TW SC) intersections are based on gap acceptance models. Critical gap is one o f the major parameters for gap acceptance models. The accuracy of capacity estimation is mainly determined by the accuracy of the critical gap. This p aper focuses on the implementation of the maximum likelihood technique to m easure a driver's critical gap using field data. A methodology to define ga p events is proposed, so that the accepted gaps and maximum rejected gaps r equired by the maximum likelihood technique could be obtained. Specific iss ues regarding multi-lane situations and major street right turn movement ar e discussed. Special conditions observed during the research are addressed when the proposed method cannot be applied directly, such as the existence of a mid-block refuge area where minor street drivers can seek gaps in a tw o-stage process, pedestrian blockage, and downstream queue spill back. The proposed method was adopted in measuring critical gap under US conditions d uring a research project, described by Kyte et al. (1996). (C) 1999 Elsevie r Science Ltd. All rights reserved.