Research on the deployment locations for coordinated variable message signs and voice warning systems on eight-lane freeways under high-wind conditions

Under extreme high-wind conditions, vehicles on bidirectional eight-lane freeways should exit safely in advance. Relying on a single variable message sign (VMS) is insufficient to effectively guide vehicles in the innermost lane to exit the freeway. This study proposes installing an additional coordinated “VMS + directional voice warning” system upstream of existing facilities to enhance exit guidance before the closed control zone. By constructing a highly realistic driving simulation scenario, the influence of deploying the system at three upstream locations—1200 m, 2200 m, and 3200 m from the diversion point—on driver exit behavior was systematically compared. A multi-dimensional evaluation index system integrating longitudinal speed adjustment and lateral lane-changing operations was established, focusing on behavioral characteristics such as deceleration and lane changes performed by drivers to complete the exit maneuver. Experimental results indicate that the system installed at 2200 m provides optimal exit guidance effectiveness: the initial deceleration point after drivers receive the information is approximately 93% earlier than in the 1200 m scenario; lateral lane-changing behavior is more concentrated and stable, with the safety margin after completing all lane changes increasing by 47% and 12% compared to the 1200 m and 3200 m scenarios, respectively, significantly enhancing exit safety. This location, by effectively balancing “timely response” and “safe comfort,” best facilitates smooth and safe freeway exits, confirming that an audiovisual coordinated guidance device installed 2200 m upstream can systematically optimize exit behavior and provide crucial evidence for emergency management on wide freeways under adverse weather.