To improve driving safety on superhighways, longitudinal profile design parameters of a superhighway are calculated via force analysis while a car is driven on a slope. The calculations consider characteristics of drivers, cars, and roads. According to the vehicle type, design speed, and natural conditions, the maximum longitudinal slope of a superhighway is calculated and compared with those of an ordinary superhighway and high-speed railway. Based on analysis of the vehicle climbing performance, braking performance, and driver visual characteristics, the maximum and minimum slope lengths of a superhighway are calculated. By analyzing the elements of vertical curves, the minimum radius and minimum length of the vertical curves of a superhighway are calculated by considering factors such as mitigating the impact at the slope bottom, driving at night, and driving time along vertical curves. Analysis and calculation results show that when the maximum longitudinal slope is 2.50%, 2.25%, and 2.00%, the minimum slope length is 450 m, 400 m, and 350 m, respectively, and the minimum vertical curve length is 145 m, 130 m, and 115 m, respectively, and the superhighway travel requirements can be satisfied at speeds of 180 km/h, 160 km/h, and 140 km/h, respectively.

中文翻译：

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高速公路纵向轮廓设计的理论研究

为了提高在高速公路上的驾驶安全性，当在斜坡上驾驶汽车时，通过力分析计算出高速公路的纵向轮廓设计参数。这些计算考虑了驾驶员，汽车和道路的特性。根据车辆类型，设计速度和自然条件，计算出高速公路的最大纵向坡度，并将其与普通高速公路和高速铁路的最大纵向坡度进行比较。基于对车辆爬坡性能，制动性能和驾驶员视觉特性的分析，可以计算出高速公路的最大和最小坡度。通过分析竖曲线的元素，考虑诸如减轻斜坡底部的冲击等因素，计算出高速公路的竖曲线的最小半径和最小长度。晚上开车，开车时间沿垂直曲线行驶。分析和计算结果表明，当最大纵向坡度为2.50％，2.25％和2.00％时，最小坡度分别为450 m，400 m和350 m，最小垂直曲线长度为145 m，130分别为m和115 m，并且可以分别在180 km / h，160 km / h和140 km / h的速度下满足高速公路行驶的要求。