| In recent years,due to the strong support of national policies and the unremitting efforts of the majority of technologists,China’s highway transportation industry has developed steadily,and the total mileage and density of highways have further increased.However,we should also pay attention to the resulting traffic safety issues.Vehicle speed and lateral deviation are two key risk factors closely related to traffic accidents,and the driver mainly obtains road information through the vision system.Therefore,based on the driver’s visual characteristics,this paper studies the expressway speed control and lane keeping technology and proposes corresponding measures to improve the safety of the expressway.According to the research results and mechanism of the existing visual illusion deceleration markings,a new form of speed control marking is proposed.The marking block forms a certain angle with the edge of the carriageway,the marking blocks on both sides gradually converge and the spacing distance between the adjacent markings is gradually becomes smaller.The design parameters of the marking were studied,meanwhile,a high-frequency roadside column was proposed to provide additional visual information to assist the speed control marking to force the driver to slow down.12 sets of speed control measures were obtained.According to the mechanism that optical flow rate and edge rate affect speed perception,the stimulation of subjectively equal speed(SSES)is used to measure the perceived speed.Furthermore,it is studied why the spacing distance between the adjacent delineators which hanging on the left wall of the expressway tunnel affects the driver’s perceived speed.According to the existing research theories and results of lane keeping technology,for the phenomenon that the vechile deviates from the tunnel wall when driving on the overtaking lane,the asymmetric visual information is used to analyze the design parameters of the asymmetric edge rate marking,and then studying the influence of the marking on the lateral position of vehicles driving on the overtaking lane.9 sets of lane keeping measures were obtained.For speed control measures and lane keeping measures,models are constructed by using UC-win/Road software,and then driving simulation experiments are carried out and data are collected.In view of the effectiveness and safety of the measures,the speed reduction rate,deceleration and the distance between the vehicle and the speed control marking at the beginning of deceleration are used as the evaluating indicators for the speed control measures,meanwhile,the difference in the distance between the vehicle and the left border and the experimenter’s score are used as the evaluating indicators for the lane keeping measures.Using the weighted rank-sum ratio method to evaluate the measures.Finally,the optimal speed control measure is scheme 12 and the optimal lane keeping measure is scheme 4.For the spacing distance between the adjacent delineators which hanging on the left wall of the expressway tunnel,models were constructed by using UCwin/Road software,and then conducting an indoor simulation experiment based on the forced choice method to obtain driver’s perceived speeds which corresponding to different spacing distances.The recommended spacing distance is 4m,which affects the speed perception of the driver in the tunnel,and then enables the driver to drive at a certain speed.The research results of this paper enrich the form of visual illusion speed control markings,give the recommended spacing distance between the adjacent delineators which hanging on the left wall of the expressway tunnel,and verify the beneficial effect of asymmetric edge rate marking on the lateral position of vehicles which driving on the overtaking lane in expressway tunnels.The proposed measures are conducive to improving the safety of the expressway,and provide new ideas for the research of speed control and lane keeping technology used on expressways. |
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