Effects of Variable Message Sign Content on Driving Behavior in an Expressway Exit-Diversion Scenario Under Crosswind-Induced Traffic Control

Crosswind-induced traffic control can require drivers to interpret diversion guidance and complete successive lane changes within limited distance. This study compared four variable message sign (VMS) configurations for upstream exit diversion on an eight-lane divided expressway. Thirty drivers completed simulator trials under single-phase text (A, baseline), two-phase text (B), graphic–text symbol (C), and graphic–text arrow (D) configurations. The VMS was positioned 750 m upstream of the diversion point, and no crosswind forces were applied to the simulated vehicle. Six metrics assessed response timeliness and driving stability. Repeated-measures ANOVA showed significant overall differences among configurations for all six metrics. Compared with Scheme A, Scheme D shifted first lane-change initiation 50.05 m upstream on average and reduced mean lane-change duration by 0.34 s (5.6%). Longitudinal acceleration variability and peak braking intensity decreased by 20.5% and 27.2%, while mean steering control intensity and peak steering control amplitude decreased by 8.1% and 14.8%, respectively. Scheme C had the most favorable mean values across all six metrics. The tested graphic–text configurations showed no behavioral deterioration indicative of information overload. These findings support the tested graphic–text configurations for upstream diversion, although the independent effects of individual information elements could not be isolated.