Traffic Congestion Evaluation Method for Urban Arterials

Abstract

Quantitative analysis of traffic conditions provides a benchmark for evaluating traffic states for effective operation and management. Most existing studies focus on measuring congestion in freeway continuous traffic flow. This paper quantifies states of urban interrupted traffic flow by using field traffic data from arterial roads in Changzhou, Jiangsu Province, China, as a study case. Development of the average congestion index considered traffic volumes on various segments to reflect the congestion state of the entire road. The congestion travel rate reflected the difference between the studied state and the free-flow state. The two indexes were adopted for measuring congestion quantitatively for both weekday (March 24, 2010) and weekend (March 28, 2010) traffic. In addition, the fuzzy clustering method was used to obtain threshold values for various traffic states, and three states were proposed from the empirical study on traffic conditions in Changzhou. Under this classification, congestion quantifications of field-observed trends from both the weekday and the weekend were found to be consistent with the definitions of the Urban Traffic Management Evaluation System of China. This finding further validated the effectiveness of the proposed average congestion index indicator.