Analysis of the differential per-lane speed limit on freeways considering safety and efficiency

The differential per-lane speed limit (DPLSL) is a type of speed control for freeway traffic management in some countries. However, there is no unified standard for the maximum and minimum speed limits for individual lanes. The purpose of this paper is to explore the optimal DPLSL combination scheme on freeways considering safety and efficiency. We simplified the traffic composition to fast and slow vehicles. The slow-start rule was introduced based on the Nagel-Schreckenberg (NaSch) rule and considered the relative speed of adjacent vehicles, acceptable gap, and safety distance to establish lane-changing rules. To reflect the driver’s lane change differences, the lane-changing probability of different types of drivers was calibrated by UC-win/road software and driving simulator. In the numerical simulation, six different DPLSL combination schemes were established, and the effects of each speed limit scheme on different traffic flows and different proportions of slow vehicles were separately analysed. The defined safety performance and operation efficiency of traffic flow via the entropy weight method (EWM) were adopted to determine the weight of each index to comprehensively consider various safety and efficiency indexes. The optimal DPLSL combination scheme was obtained through evaluation of the comprehensive indicators.