Improvement Measure Of Freeway Heavy Truck Influence Based On Simulation

The percent of heavy trucks increases gradually in recent years, and trucks become longer and heavier which brings a worse effect to traffic operation and safety. With the increase of volumes, the level of service of freeway decreases rapidly. As far as the causes are concerned, only a few freeways achieve the capacity.The reason is that for most freeways there are many overloading and overrunning vehicles with poor performances mixed with other high-speed vehicles in freeways which leads to a great number of "moving bottleneck" along the freeways. The phenomenon becomes more obvious on the upgrade, sharp turn section, which are worsen by overloading.Choosing a reasonable method to relieve the bad effect of heavy truck and maximizing the service ability of the freeway system have become a top priority in China's traffic system in order to insure the freeway system exerting their ability to the full. Based on flow-density relation of moving bottleneck, source control and traffic flow control were put forward to mitigate the unfavorable influence. Traffic flow control measure is consists of two aspects:the increase of lane number and truck restriction, which is diversified. And the effects on traffic characteristics under different measures are various, so selecting an appropriate scenario is a key point.Test schemes are designed as follows:existing roads(â… ), climbing lanes(â…¡), widen lanes(â…¢), truck lane restrictions(â…£). Basic on the traffic investigation and analysis, microcoomic simulation software TSIS is put forward to develop the traffic simulation resreach and establish the topological structure of nanning-wuhe section, calibration parameters, evaluation parameter of operation and safety, simulation times and etc.Schemeâ… ,â…¡,â…¢is analyzed as widening lane projects, which taking aim at optinal investment efficiency, and using cost-effectiveness graph to evaluate the effects of different widening projects.The simulation results suggest that the existing road is not needed to be meliorated, unless the truck percent is more than 40% which need to set climbing lanes, and the volume is higher than 1000veh/h/ln, with the truck percent is more than 50%which need to widen to six lane in two direction. Truck lane restriction(â…£) is desired to make a deep research. Basic on the setting of traffic condition and truck lane restriction, the evaluation parameters of density, speed, and lane changes are analyzed through ANOVA variance analysis method and X,Y graphic method, the improvement effect of different truck lane restrictions and the scope of application are obtained finally, which as follow:Restricting trucks from the left-lane is not recommended in existing roads. Restricting trucks from the left lane is proposed on three-lane freeway in each direction when the flow is higher than 800veh/h/ln and the grade is steeper than 3%. Restricting trucks from the two left lanes is recommended on four-lane freeway in each direction, which is used to relieve the influence of heavy truck, and improve the operation effecting and safety of freeway as a whole.