Research On Speed Limit On Urban Street

Speed control is the primary way to makethe traffic safe and effective on urban road.The vehicle on the road at a reasonable speed, while reducing accidents for security, on the other hand increased capacity effectively and efficiently. The speed limit is one of the primary means to traffic safety protect on urban road. Reasonable speed limitwill reduce the probability and severity of the accident. when the vehicle traveledfollowing the speed limit, the velocity distribution of the dispersionand the driver to change lanes to overtake other acts owing tothe speed differential reduced, thus ensuring the traffic driving orderly and efficiently. However, the decision speed limits making is lack of theoretical support, often designed to limit the rate of speed as the basic value of the special sections and more to 20 km / h were discounted. In fact, there is a certain link between running speed and the speed limit, and it is a big difference.Acordding to the insufficient of speed limit of urban roads presented recently, the researchcarrys out.I analyze the calculation methodof essential speed combined with the existing researchand domestic standard which have been published,then quantify the value of the factor whicheffect on the speed, and proposeevaluation of speed limit. it takes basic both speed Vsafeselecting steady flow conditions of the road conditions and speed Vi selecting Vsafe as an ideal vehicle for the basic values linear.There were four aspects: the free flow of running speed situations entrance number, average lane width, road-side interference and impact analysis four road conditions, for each aspect of the calculation of the basic value, thenconsolidatesections,set a reasonable speed transition section.Finally, it provide to evaluation by vissim software which can simulation the environment and enhancing supervision and inspection of speed limit zones,until it qualified.Use results of this study, that "guidelines for establishing posted speed limit" on the actual project in the urban roads the speed limit value determined, has some practical significance.