Simulation Of Operating Speed On Mountainous Two-lane Highway

With the development of the society and the increasing of traffic mileage and vehicle population, the traffic accidents have become one of the most serious damage. Mountain accounts for more than 70% of national area. Due to terrain condition, weather, and environment reasons, serious traffic accidents happen on mountain area frequently. The safety of vehicle driving on mountainous area has to be focused on. Many traffic accidents happen because of over-speed.The design speed is mainly used as the main basis for word design, which all the road alignment parameters must be matched with. The design speed is the maximum speed on the restricted road sections. The ratio of restricted road sections is not very large, so vehicle can drive over design speed on other road sections. Then the highway alignment continuity can not be ensured. Research on the model of operating Speed provide reasonable basis for the safety of alignment design and road safety evaluation.The operating Speed forecast, which relies on the National Science Foundation" simulation of road alignment design and safety evaluation", predicts and simulates the operating Speed through software program and evaluates the continuity and safety of the road sections.Firstly, after analyzing the traffic safety condition of two-lane highway and domestic and international research on operating Speed, an overall framework is established.Secondly, the concept of operation speed is explained on this paper and the application of the speed in road design is explained. The paper introduces the effect of each factor of road traffic system on operating Speed in detail, which provides the theoretical foundation for the forecast model of operating Speed.Thirdly, the road is divides into 4 kinds of sections (straight line segment, curve line segment, slope segment, slope and curve segment). Different Longitudinal kinds of models are established according to different working station, which can supply available evidence and method for computer simulation.Moreover, it has taken one week to experiment on antu-erdaobaihe second highway, using the speed-measuring system. Horizontal curvature is calculated by longitude and latitude, measured by Driftbox. Longitudinal slope and super elevations are measured through digital balance level. The visual range is measured by laser ranger finder. The operating Speed can be obtained by S3 radar and Driftbox and the operating Speed database is set up in mountain area.At last, according to the need of overall framework and the speed simulation model, system flowchart is developed. The predicting program is established by Matlab language and GUI interface. The accuracy and practicality of the model are proved by the experiment data from road sections,K7+600 to K7+900 forward and backward, K27+000 to K27+900 forward and inverse and K42+900 to K43+200 forward and inverse. The model can reflect the real character of the operating speed. Then the traffic safety and speed continuity are evaluated and effective advice is given.