山区高速公路上坡路段合理速差研究

Reasonable speed difference on uphill section of mountainous freeways

为了明确山区高速公路上坡路段,货车行驶速度与路段上交通流平均速度的差值对通行效率和安全影响,研究了客车和货车合理速差范围,在西汉(西安—汉中)高速K1185+120～K1185+820段进行实测试验。利用AxleLight RLU11便携式路测激光交通调查仪,实时收集车辆位置、类型、速度、车头时距、时间间隔等交通数据。根据车头时距筛选车队,分别建立速差、平均速度数据库。利用SPSS软件进行正态分布检验,在确保数据有效性的前提下,建立以速差为自变量、以平均速度为因变量的非线性回归模型,通过与无货车混行车队的平均速度进行比较,得到影响通行效率的客货车速差最大阈值。研究结果表明:货车的混行对通行效率有较大影响,与无货车混行相比,其平均速度减小13.6%;速差与平均速度呈二次相关的关系,随着速差的增大,平均速度呈现出先增大后减小的趋势;为了保持良好的通行效率,速差的最大阈值为21km/h。

Aimed to study the traffic efficiency and safety enabled by the speed difference between trucks and regular traffic flow on the uphill section of a mountainous freeway.A field experiment was carried out in Xihan（Xi’an to Hanzhong）Freeway from K1185＋120 to K1185＋820.Traffic data consisting of location,speed,headway time,interval and vehicle type,which were collected on a timely basis using AxleLight RLU11.Platoons were chosen according to vehicular headway,and then,the database comprising speed difference and average speed were built.After the normal distribution test,the regression model was established with the speed difference as the independent variable,and the average speed as the dependent variable through SPSS.The threshold value of speed difference influencing traffic efficiency was further determined,compared to the platoon without trucks.The results show that mixed driving with trucks has a considerable influence on traffic efficiency.The average speed of a platoon with trucks shows a significant decrease,about approximately 13.6%compared to a platoon without trucks.Speed reduction has aquadratic correlation with the dispersion of average speed,traffic efficiency can be well maintained by limiting the allowable speed reduction to approximately 21 km/h.