فهرست نشریات علمی دسترسی آزاد ایران

This paper describes an attempt to develop congestion indices for a developing country with a limited sampling. Speed and ow rate information was collected from urban highway trac ow videotaping in Iran. Video display provided information for trac modeling when, similar to most of the developing nations, Iran does not have locally developed highway capacity manuals. Processing of the extracted data and trac modeling provided free and capacity ow information for the selected freeway and principal arterial sections for the capital city of Tehran. The congestion indices were associated, in simple and logical models, with ve trac descriptive variables of travel speed, travel rate, delay rate, travel rate ratio and delay ratio, respectively. To calibrate the congestion index models, specic congestion levels were assessed by the index values under free and capacity ow conditions. The functional forms used in congestion index modeling were derived from the congestion rate of change, simple, reasonable and relevant assumptions. For comparison, index models, based on the US Highway Capacity Manual, HCM, speed and ow rate information, were also developed. The developed indices were suggested as feasible and included quick response measures for congestion monitoring and control when trac management resources are often limited and scarce. Based on the preferences of a group of transportation professionals and university students, the relative importance of each of the individual indices, as average weighting value, was identied. Using the average weighting values, an overall congestion index was also developed. The overall congestion index was suggested as a complimentary or alternative measure for congestion intensity assessment and evaluation. The study ndings were based on a rather limited database and were location specic; nevertheless, for quick response congestion index development, the applied methodology could be used by any developing country. The suggested indices have potential in trac management and congestion mitigation.