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根据城市快速路的特性,将城市快速路分为基本路段、交织区和分合流区。运用Greenshields模型计算自由流行程速度,通过双线圈检测器获取地点速度并由此估算行程速度。对行程速度指数进行右侧均值和均方差的一致性检验,将服务水平量化,提出了基于行程速度指数的城市快速路服务水平评价方法,并在西安市南二环某路段上进行实例验证。评价结果表明:当自由流、高峰时段、平峰时段的行程速度分别为82.514、47.825、67.930km·h-1时,高峰时段行程速度指数的均值和均方差检验结果分别为7.206、8.482,城市快速路服务水平为2.667,为Ⅲ级;平峰时段行程速度指数的均值和均方差检验结果分别为6.408、8.960,城市快速路服务水平为4.083,为Ⅱ级。计算结果与实际情况相符,提出的方法有效。
According to the characteristics of urban expressway, the urban expressway is divided into basic sections, intertwining areas and sub-converging areas. The Greenshields model is used to calculate the free-run speed and the dual-coil detector to obtain the speed of the location and hence the travel speed. We test the consistency of the mean and the mean square error of the travel speed index, quantify the service level, and propose the evaluation method for the urban expressway service level based on the travel speed index. Finally, an example is used to verify the travel speed index in a section of South Second Ring Road in Xi’an. The evaluation results show that when the free-flow, peak-hour and peak-peak travel velocities are 82.514, 47.825 and 67.930 km · h-1 respectively, the average and mean-square-deviation test results of the travel time indices at peak hours are 7.206 and 8.482, The road service level is 2.667, which is Grade III. The average and mean square deviation test results of the travel speed index during the peak hour are 6.408 and 8.960, respectively. The service level of the urban expressway is 4.083, which is level II. The calculation results are in accordance with the actual situation and the proposed method is effective.