Driver behavior at straight lane offset intersections: effects of dual-modal guidance in a driving simulation study.

OBJECTIVE: Straight lane offset at urban signalized intersections creates discontinuity between entry and exit lane alignments, potentially increasing drivers' path uncertainty and unsafe trajectory interactions. This study investigates how lane offset affects driving behavior and evaluates whether dual-modal guidance combining navigation voice prompts and pavement guidance markings can mitigate its adverse effects. METHODS: A driving simulation experiment was conducted with 39 drivers under six experimental scenarios combining three intersection configurations (baseline, offset, and optimized) and two traffic conditions (free-flow and steady-flow). Driving performance was evaluated using indicators of longitudinal control, lateral control, and traffic conflicts. Repeated-measures analysis of variance (ANOVA), trajectory-based spatial analysis, and fuzzy comprehensive evaluation were applied to examine behavioral differences and overall scenario performance. RESULTS: Straight lane offset degraded trajectory alignment and increased conflict potential. Under steady-flow conditions, the lane-matching degree decreased from 0.92 in the baseline scenario to 0.44 in the offset scenario, while the number of conflict points increased from 2 to 17. With dual-modal guidance, the lane-matching degree improved to 0.79, and the number of conflict points decreased to 2, matching the baseline scenario. Traffic conditions mainly influenced longitudinal control, whereas lane offset had a stronger effect on lateral trajectory organization and conflict-related outcomes. CONCLUSIONS: Straight lane offset disrupted trajectory organization by increasing lateral deviation, reducing lane-matching performance, and increasing conflict potential. Dual-modal guidance improved trajectory organization and lane-matching performance. The findings provide empirical evidence for low-cost safety improvements at existing offset intersections where geometric reconstruction is constrained.