From “warning” to “guidance”: design of a closure control zone for eight-lane freeways and evaluation of its regulating effects on driving behavior

Introduction: Emergency closures of eight-lane freeway mainlines require vehicles to execute multiple successive lane changes to detour, a maneuver that is more complex and risky than on narrower freeways. Current standards lack tailored control zone designs and empirical evidence for such scenarios. Methods: To address the lack of standards for eight-lane freeway full closures, a control zone was designed based on the principle of "active guidance, graded transition, and terminal enforcement." Recognizing the complexity of multiple mandatory lane changes, two warning signs were developed: a basic version and an enhanced version adding the advisory "Merge Right for Detour." A 2 × 2 factorial driving simulator experiment (sign type × weather condition) involving 30 licensed drivers was conducted to evaluate lateral and longitudinal driving behavior. Results: The enhanced "Warning & Advice" sign consistently improved driving performance. It prompted earlier lane-change initiation (by 966 m in clear weather and 610 m in dusty weather) and reduced the aggressiveness of three successive lane changes (by 35.8, 23.8, and 23.5% in clear weather; the first two by 49.3 and 31.3% in dusty weather). Longitudinally, it decreased maximum deceleration aggressiveness by 21.7% (clear) and 25.1% (dust) and improved deceleration smoothness by 16.0 and 25.4%, respectively. Dusty weather amplified these benefits, indicating a synergy between environmental caution and explicit guidance. Discussion: Incorporating actionable advice into warning signs optimizes driver decision-making and shifts the control strategy from passive "warning" to active "guidance." The findings provide an empirical basis for the design of closure control zones and demonstrate that well-designed information can compensate for environmental uncertainty, thereby enhancing safety in complex multi-lane closures.