城市快速路中央分隔带线性空间布局形式的视觉刺激对驾驶行为的影响

为探究城市快速路中央分隔带线性空间布局形式的视觉刺激对驾驶行为的影响，通过图像语义分割技术量化景观构成要素，并用SILAB软件平台构建虚拟仿真场景，开展模拟驾驶试验。测试路段限速值分别为50 km·h^-1和70 km·h^-1。试验获取了41名被试对中央分隔带布局形式视觉刺激的眼动和车辆运行指标以及驾驶疲劳的主观评价，以分析不同中央分隔带布局形式视觉刺激下各特征参数的变化规律。采用注视点信息熵作为布局形式视觉刺激度的量化指标，并使用ROC曲线方法为表征不同中央分隔带布局形式视觉刺激的驾驶行为指标确立了舒适性阈值，根据不同中央分隔带布局形式下的驾驶行为指标及阈值，建立了舒适性综合判别模型。研究结果表明：单次扫视时长、注视次数、车道横向偏移距离受布局形式视觉刺激的影响较大；与车速50 km·h^-1相比，当车速为70 km·h^-1时，扫视频率低，单次扫视时长短，注视次数少，平均眨眼持续时间长；注视点信息熵与视觉刺激度相关；由车辆运行特征分析可知，排列式的中央分隔带布局形式由于景观单调、视觉刺激过低会导致驾驶人出现反应迟缓、疲劳，影响行车安全；规则式布局形式视觉刺激过高，环境的复杂性、新奇性、意外性等特征过于显著，会导致驾驶人难以集中注意力，从而威胁行车安全；而自然式的布局形式不仅能够改善城市快速路景观环境的单调性，还能够提供适宜的视觉刺激。研究成果能够改善中央分隔带布局形式及提高驾驶安全性提供一定的理论依据。

Influence of Visual Stimuli on Driving Behavior in the form of Linear Spatial Layout of Urban Expressway Median Strip

In order to investigate the influence of visual stimuli on driving behavior in the form of linear spatial layout of urban expressway median strip, this paper quantified the landscape components by image semantic segmentation technology and constructed a virtual simulation scenario using SILAB software platform to conduct a simulated driving test with speed limits of 50 km·h^-1 and 70 km·h^-1. Through the test 41 subjects' evaluations of eye movements and vehicle operation indexes as well as driving fatigue were obtained to analyze the changes of each characteristic parameter under the visual stimulation of different median strip layout forms. We adopt the information entropy of gaze points as the quantitative index of visual stimulation of layout forms, and use the ROC curve method to establish the comfort threshold for the driving behavior indexes characterizing the visual stimulation of different center divider layout forms. A comprehensive discriminatory model of comfort is established according to the driving behavior indexes and thresholds of different center divider layout forms. The results demonstrate that the single sweep length, the number of gazes and the lane lateral offset distance are influenced by the visual stimulation of the layout form. Compared with the speed of 50 km·h^-1, when the vehicle speed is 70 km·h^-1, the sweep frequency is low, the single sweep length is short, the number of gazes is low and the average blink duration is long. Moreover, the information entropy of the gaze point is related to the visual stimulation degree. An analysis of the vehicle operation characteristics shows that due to the low visual stimulation the arranged median strip layout form tends to cause drivers' slow reaction and fatigue because of the monotony of the landscape thus affecting the driving safety; on the other hand, due to the high visual stimulation the regular layout form tends to cause drivers' difficulty in concentrating because of the high characteristics of complexity, novelty and unexpectedness of the environment, thus threatening the driving safety; and the natural layout form not only improves the monotony of the urban expressway landscape environment, but also provides suitable visual stimulation. This paper can serve as a theoretical basis for improving the quality of urban expressway environment and driving safety.