Alternative Methodology for Determining Gap Acceptance for Two-Way Stop-Controlled Intersections

Vehicles approaching a two-way, stop-controlled intersection from the minor roadway will wait for a large enough gap in the traffic on the major roadway before entering the intersection. The primary method for modeling intersections for both safety and operations is to determine a critical gap size such that a vehicle waiting at the stop sign will enter the intersection if the gap on the major roadway is larger than the critical gap. The method that is currently most accepted for measuring the critical gap is a maximum likelihood estimation developed by Troutbeck. The Troutbeck method may yield biased results and cannot be used with data sets that contain only rejected gaps. This paper proposes an alternative model for estimating the critical gap that is unbiased and can be used with naturalistic data. The proposed model requires that the gap distribution of the major street be known. This proposed model is compared with the Troutbeck model through a Monte-Carlo simulation. The proposed model yields accurate estimates of the mean critical gap as long as accurate estimates of the major street traffic are used.