Cooperative Vehicle Infrastructure System-Based Control Strategy of Variable Speed Limit to Reduce Crash Risks in Freeway Bottlenecks

This paper develops a variable speed limit method based on cooperative vehicle infrastructure system (CVIS) to reduce the risk of accidents, alleviate road congestion, and improve the operation efficiency on the freeway. Facing the problem of real-time information interactions of variable speed limit control, CVIS based on wireless sensing technology to achieve information interconnection and mutual sharing between vehicles and infrastructure provides a new platform for developing domestic variable speed limit control systems. This research aims to reduce the risk of road accidents by using surrogate safety measures to construct the objective optimization function and restricting the two control parameters (length of control sub-section, value of regional speed limit) according to actual application constraints. Results show the proposed strategy outperforms the previous approach regarding surrogate safety measures' reduction and total time spent saving. The time-exposed time-to-collision is reduced by 36.27%, and the time-integrated time-to-collision is reduced by 40.16% on average.