Resumen
In weaving segments, traffic merges, diverges, and weaves in a limited space. These traffic maneuvers might result in high crash hazards. To improve the safety of congested expressway weaving segments, this study tested several variable speed limit (VSL) strategies in a well-calibrated and validated microsimulation (VISSIM). Ten simulation runs? worth of results showed that 96.4% of the simulated volume and 86.46% of the simulated speeds were consistent with those of the field. The VSL was activated in simulation only when traffic was in hazardous conditions, and the status of VSL was updated every 5 minutes. Crash odds and conflict counts were used to evaluate the impact of VSL strategies on traffic safety. The crash odds were calculated based on a real-time safety analysis model for weaving segments, and the conflicts were obtained by processing VISSIM vehicle trajectory file in the Surrogate Safety Assessment Model (SSAM). The results showed that both the location and the speed value of VSL were important. The VSL installed at the upstream of the weaving segment better enhanced the safety than the VSL set at the downstream. Hence, the reduction of upstream speed is the key to improve the safety of weaving segment. Furthermore, lower upstream variable speed limit would better improve the safety of the whole weaving segment.