Urban Road Traffic Congestion Measurement And Identification

Urban road traffic congestion is one of the most serious problems during urbandevelopment. Exactly measuring congestion is beneficial to implement targetmeasures, means and measures to mitigate congestion. Therefore, urban road trafficcongestion identifaction and comprehensive evaluation of urban road trafficcongestion is important for improving the efficiency of urban transportation andeasing traffic congestion. This paper studies the followings:On the basis of analysis on the relationship between traffic flow parameters ofurban expressway, according to speed transition probability and traffic flow stability,using occupancy and speed the traffic flow is divided into four states: high-speedsteady flow, high-speed unsteady flow, low-speed unsteady flow, low-speed steadyflow. Then using transportation efficiency to evaluate traffic flow state, the resultsshow the transportation efficiency of traffic flow changes when state transitions.In order to make up inadequate research on traffic congestion identification byroad section detector. Based on the traffic state division parameters occupancy andspeed, a congestion identification method is created by speed-occupancy ratio andspeed difference to identify the time of congestion occurrence and over. Aftercalibrating two indicators threshold by Beijing2rd urban expressway data, thisidentification method is applied to identify congestion; the result shows that thismethod can exactly identify congestion.In order to comprehensively evaluate urban traffic congestion, urban road trafficcongestion evaluation system is established, taking into account the variousdimensions of congestion, including the time cost and energy loss caused bycongestion. Travel time index is used to build an urban transport travel time indexmodel measuring congestion severity comparable on time and space. Researchenriches the traffic congestion measurement.