Traffic Congestion Evaluation Method For Urban Arterials: A Case Study Of Changzhou, China

Quantitative analysis of traffic conditions provides benchmark in evaluating traffic states for effective operation and management, while the majority of existing studies was focused on measuring congestions of freeway continuous traffic flow. This paper aims to quantify states of urban interrupted traffic flow by using the field traffic data from arterial roads in Changzhou, Jiangsu province, China as a study case. The Average Congestion Index (ACI) indicator was developed by considering traffic volumes on different segments to reflect congestion state of entire road. Then, in combining with the Congestion Travel Rate (CTR), which reflects the difference between the studied state and free flow state, the two indices were adopted to measure congestions quantitatively for both weekday (Mar. 24, 2010) and weekend (Mar. 28, 2010) traffic. In addition, Fuzzy Clustering Method (FCM) was used to obtain threshold values for various traffic states, by which three states were proposed from the empirical study on the traffic conditions in Changzhou. Under this classification, congestion quantifications of field observed trends from both weekday and weekend were found to be consistent with the definitions from Urban Traffic Management Evaluation System of China (UTMES). This further validated the effectiveness of the proposed ACI indicator.