Zhao Xiaohua, Wu Yiping, Rong Jian, Ma Jianming
Beijing University of Technology, College of Metropolitan Transportation, Beijing 100124, China.
Texas Department of Transportation, 10016 Liriope Cove, Austin, TX 78750-2636, USA.
Accid Anal Prev. 2015 Feb;75:226-35. doi: 10.1016/j.aap.2014.12.004. Epub 2014 Dec 16.
To develop a practicable and clear guideline for implementing Chevrons on China's highways, it is necessary to understand the effect of Chevrons on driving performance in different roadway geometries. Using a driving simulator, this study tests the effect of China's Chevrons on vehicle speed and lane position on two-lane rural highway horizontal curves with different roadway geometries. The results showed a significant effect of Chevrons on speed reduction, and this function was not significantly affected by curve radius but was statistically affected by curve direction. The speed reduction caused by Chevrons was also significant at the approach of curve, middle of curve and point of tangent. The 85th percentile speed was also markedly lower when Chevrons were present. We also found a significant effect of Chevrons in encouraging participants to drive the vehicle with a more proper lane position at the first half of curves; and this function was slightly affected by curve radius. Meanwhile, the effect of Chevrons on keeping drivers staying in a more stable lane position was also statistically significant at the second half of curves. In sharp curves, the function of Chevrons to make drivers keep a stable lane position was lost. Besides, the impact of curve direction on the function of Chevrons on lane position was always present, and drivers would drive slightly away from Chevrons. Regardless of the curve radius, China's Chevrons at horizontal curves provide an advance warning, speed control and lane position guide for traffic on the nearside of Chevrons. Besides, combing with the function of Chevrons on preventing excessive speed and the benefit to make drivers keep a more proper lane position, China's Chevrons appear to be of great benefit to reduce crashes (e.g., run-off-road) in curves.
为制定一套切实可行且清晰的中国高速公路上实施人字形标线的指南，有必要了解人字形标线在不同道路几何形状下对驾驶性能的影响。本研究使用驾驶模拟器，测试了中国的人字形标线对不同道路几何形状的双车道农村公路水平曲线上车辆速度和车道位置的影响。结果表明，人字形标线对速度降低有显著影响，且该功能不受曲线半径的显著影响，但在统计学上受曲线方向的影响。人字形标线在曲线起点、曲线中点和切线点处导致的速度降低也很显著。当设置人字形标线时，第85百分位速度也明显更低。我们还发现，人字形标线在鼓励参与者在曲线前半段以更合适的车道位置驾驶车辆方面有显著影响；且该功能受曲线半径的影响较小。同时，人字形标线在曲线后半段使驾驶员保持在更稳定的车道位置方面的影响在统计学上也很显著。在急弯中，人字形标线使驾驶员保持稳定车道位置的功能丧失。此外，曲线方向对人字形标线在车道位置方面功能的影响始终存在，驾驶员会稍微偏离人字形标线行驶。无论曲线半径如何，中国高速公路水平曲线上的人字形标线为标线近侧的交通提供了提前预警、速度控制和车道位置引导。此外，结合人字形标线防止超速的功能以及使驾驶员保持更合适车道位置的益处，中国的人字形标线似乎对减少曲线中的碰撞（如驶离道路）有很大益处。
