Study On The Evolution Of Urban Regional Traffic Flow Under The Condition Of Snow And Ice

Traffic congestion has become the common problem of China's major cities and regional road network. Snow and ice conditions not only reduce the traffic capacity of roads, increase traffic jams, and the worse is that the traffic congestion at local intersections or roads may spread to adjacent roads or intersections, causing massive area traffic jams. Study on the evolution of urban regional traffic flow and the spread of congestion under the condition of snow and ice, has a very practical and significant meaning on the relief of traffic congestion and avoid massive paralysis on urban road network.This paper research on the traffic flow of the urban road network basic unit—the intersection and the road section in snow and ice conditions based on the review of the current situation at home and abroad. First of all, the saturation flow rate and vehicle arrival rates at the intersection, point speed and road capacity and other parameters related to traffic flow are observed by video recording method. Get the mathematic relational model between traffic flow parameters and snowfall. Then, the vehicle operation characteristics at intersection under the snow and ice conditions are analyzed, a delay model based the length of queue is posed, select the average delay of vehicles to divide the state of traffic flow at intersections, which cross into four state such as smooth, mild congestion, crowding and blocking. Examined the transformation laws of the traffic flow state, give out the various threshold to determine the division between the states based on the relevant standard home and abroad. Then, similarly, the vehicle operation characteristics on road section under the snow and ice conditions are analyzed, Select the location speed indicators is selected for the division index, which cross into four state such as free traffic flow, car flow, congestion flow, plug flow, examined the transformation laws of the traffic flow state, and the threshold between the traffic flow states was gave out using self-organizing neural network.Finally, from a system point of view, a single point of traffic congestion on roads and intersections have impact on the adjacent network, traffic congestion diffusion mechanism in the network is analyzed, describe the traffic jam with queue length in the spread of a single point and proposed the estimation of traffic jam spread based traffic congestion at intersection and road section separately.