Model of Quantitative Evaluation of Traffic Circulation Plan Based on Traffic Conflicts

Traffic impact studies (TIS) have been required by transportation agencies to evaluate the potential transportation impacts of the proposed development on the surrounding neighborhood since 2001 in Beijing. The analysis on the negative aspect brought by proposed projects in terms of improper location and excessive number of driveways or inappropriate opening of median becomes the focus of TIS. However, the analysis of the traffic conflicts generated by proposed development has been so far limited to qualitative interpretation and conflict diagrams in traffic impact reports, which makes it difficult for traffic professionals to evaluate traffic circulation plans. The objective of this paper attempts to explore to quantify traffic conflicts analysis. Concept of conflict complexity is, for the first time, introduced in this study as a new evaluation indicator. The model to estimate conflict complexity is then built up by putting vehicle-bicycle conflict, vehicle-pedestrian conflict and vehicle-vehicle conflict into consideration. This indicator can be used to quantitatively determine if traffic circulation proposed in TIS report is justified. Finally, based on the data from 65 TIS reports from Beijing city the threshold values for criterion are determined in the study. The result from this study will help transportation agencies make decision for the proposed projects in quantitative manner. In addition it can also pave the way for the standardization of traffic circulation procedure.