超高海拔区域驾驶人超车注视特性

为获取驾驶人在海拔超过3 500 m的超高海拔区域超车过程中的注视特性，应用头戴式眼动仪在青藏公路展开了实车测试，监控并记录了驾驶人眼动行为数据。通过统计驾驶人在超车各阶段对各注视区域注视及视线转移时长，应用马尔可夫理论计算4个海拔范围内超车4个阶段在7个区域上的注视平稳分布向量，应用超车各阶段注视平稳分布向量间的相关系数评价超车模式的相似性，基于相关系数矩阵的最大特征值建立注视特性的关联指数，并用其分析超车各阶段及不同海拔下驾驶人注视特性的差异。研究结果表明：驾驶人在超高海拔区域超车时，主要关注当前车道和目标车道，关注比例分别为61.8%和26.4%；超车4个阶段的关联指数分别为3.315，2.934，3.102和3.794，表明意图阶段的注视分布差异性最大，跟驰和返回阶段的差异性较小；初上高原驾驶人的平均关联指数是本地驾驶人的1.89倍，显示其更为谨慎，注视离散性更强；海拔超过4 400 m后，驾驶人注视特性的相关系数要比其他海拔段低39%，呈现出不同的特性；超高海拔区域驾驶人主要注视当前车道，注视目标车道的比例小于平原微丘区驾驶人，体现出驾驶人未能全面关注驾驶环境信息。研究结果可作为交通设施设计优化、道路主动安全预防等研究的基础。

Eye Gaze Characteristics of Overtaking Process in Very High Altitude Area

To obtain the eye gaze characteristic of an overtaking process in very high altitude areas that are higher than 3 500 m, the eye movement data from real vehicle experiments at the Qinghai-Tibet Highway was recorded using eye-tracking glasses. The fixed durations within the seven areas of the drivers' vision and the fixed transitions during the four phases of the overtaking process were collected. The Markov process was utilized to obtain the steady-state fixation distribution of every overtaking phase for the four ranges with various altitudes. The connectivity indicator was defined as the maximum eigenvalue of the correlation coefficient matrix. The differences in the drivers' fixation between various overtaking phases were analyzed using the correlation coefficients between the corresponding features and connectivity indicators. The results of the studies indicate that the fixation rates on the current lane and target lane at a very high altitude area are 61.8% and 26.4% respectively, which are the drivers' most interested area; the connectivity indicators of the four overtaking phases are 3.315, 2.934, 3.102, and 3.794, which illustrate that the purpose phase has the most significant otherness, and the car following and returning phases have similar fixation mode. The correlation coefficients obtained from the drivers that be in the very high altitude area for the first time are 1.89 times larger than those of the local drivers, indicating that they are more cautious during driving and are more discrete on their fixation. The correlation coefficient of the eye gaze characteristics of the area with an altitude higher than 4 400 m is 39.3% lower than other areas investigated, which leads to a different eye gaze pattern; the drivers at the very high altitude area will primarily focus on the current lane, while the drivers at the plain or hilly areas will have a higher fixation on the target lane, implying that the drivers at the very high altitude area should be more vigilant to the driving environment. The method proposed can determine the eye gaze characteristics of drivers in very-high-altitude areas. The results can be utilized in the fields of road infrastructure design and active safety prevention.