A dynamic speed limit control method for the confluence area considering the impact of dual bottlenecks

Dual bottlenecks based on sudden bottlenecks and fixed bottlenecks may be induced in the confluence area of expressways, which can partially undermine the advantages of expressways. To address traffic problems caused by traffic bottlenecks, a DSLC method for the confluence area considering the impact of dual bottlenecks has been determined. Traffic infarction is selected as the traffic event inducing sudden bottlenecks in the SSLC, without further considering fixed bottlenecks and the real-time changes in traffic states and corresponding speeds. Therefore, on the one hand, the CA model is improved based on consideration of DSLC, thereby determining the corresponding traffic flow evolution model. On the other hand, the dual-bottleneck problem is comprehensively considered based on the static speed limit model, thereby determining the DSLC strategy for confluence areas, and the real-time traffic infarction probability and traffic state in the confluence area are used as dual criteria for initiating speed limit control. Based on the established simulation scenario and experimental scheme mainly consisting of ISLC, SSLC, and DSLC, while a one-hour simulation experiment is conducted to extract corresponding data on speed, traffic density, CI, TR, and headway are extracted, and analysis is conducted with the data to validate the effectiveness of DSLC. Furthermore, the effectiveness of DSLC is further validated by comparing the change rate of TR with DSLC, DVSL, and DZPC. Results indicate that compared to ISLC, DSLC achieved an increase in speed and a decrease in traffic density, a 1.879% decrease in CI and a 22.819% decrease in TR. Compared to SSLC, the four indicators under DSLC exhibited identical changes. This indicates that DSLC contributes to improving traffic conditions to some extent. Compared to DVSL and DZPC, DSLC exhibits a higher change rate of TR, thereby validating the superior effectiveness of DSLC.