Examining the effects of improved signs on lane-changing behavior at expressway emergency stop area

The emergency stop area at expressways is designed to help drivers handle emergencies. However, to enter the emergency stop area, some risky lane-changing behaviors often occur. This study evaluated drivers' lane-changing behavior under various sign schemes to identify an effective sign scheme that can improve lane-changing performance when entering the emergency stop area.

Based on the pre-position distance, disappearance distance of the signs, as well as the driver's judgment distance and action distance, different sign positions and number conditions were set. A driving simulator was used to examine drivers' lane-changing behavior when approaching the emergency stop area under various sign schemes. The lane-changing behavior was divided into the decision process and the action process. The Generalized Estimating Equations (GEE) model was used to analyze five selected behavioral variables. Besides, the entropy-weighted TOPSIS model was employed to select the recommended sign scheme.

The results show that both the Single position improved (SPI) sign and the Two-stage improved (TSI) sign effectively advanced the drivers' lane-changing position by over 52.4%, increasing the lane-change success rate by more than 23.8% compared to the baseline sign. The TSI sign further increased the lane-changing speed and improved comfort compared to the SPI sign. The entropy-weighted TOPSIS model results identified TSI380 as the recommended sign scheme. Additionally, mature drivers performed better in lane-changing performance than novice drivers, and female drivers were more likely to follow the sign information.

The findings provide scientific guidance for the placement of signs before emergency stop areas. It is recommended to set signs at 380 m and 230 m before the entrance of the emergency stop area to reduce risky lane-changing behavior.