Estimating Driver Mandatory Lane Change Behavior on a Multi-lane Freeway

The driver gap acceptance and rejection behavior during mandatory lane changes on a multilane freeway are analyzed in this paper. Gaps are accepted or rejected based on comparison with a minimum value generally defined as the critical gaps. Critical gaps are estimated based on the accepted and rejected gaps observed in the field. Driver behavior can be classified as consistent or inconsistent on the basis of gap rejection. For consistent driver behavior, it is assumed that the rejected gaps are shorter than the accepted gaps. This paper focuses on the estimation of critical gaps values and its distribution for consistent driver behavior. Critical gap, for consistent driver behavior is defined as the minimum value of gap above which the lane changer does not reject a gap to execute a lane change. Several gaps may be rejected prior to a gap being accepted, therefore, different types of rejected gaps can be utilized to estimate critical gaps. To systematically evaluate rejected gaps and propose the most suitable rejected gaps for use in estimating the critical gaps, rejected gaps were analyzed using the mean rejected, median rejected, and the largest rejected gaps less than the accepted gaps (LRLA). To model the consistent gap acceptance behavior of drivers i.e. the rejected gap is less than the accepted gap, LRLA is used in estimating the critical gaps. The values of critical time gaps were estimated using the maximum likelihood estimation method. This paper utilized the data collected by the NGSIM project on I-80 during both uncongested and congested traffic conditions.