A  STUDY OF TRAFFIC SAFETY AT FOUR-LEG SIGNALIZED  INTERSECTIONS USING TRAFFIC CONFLICT TECHNIQUE

S.  Neham, Sahar; A. Ewadh, Hussein

	A STUDY OF TRAFFIC SAFETY AT FOUR-LEG SIGNALIZED INTERSECTIONS USING TRAFFIC CONFLICT TECHNIQUE
AL-TAQANI
Article 1, Volume 21, Issue 4, 2008, Pages 30-49
Authors
Sahar S. Neham; Hussein A. Ewadh
Abstract
With the absence of reliable accident record, traffic conflict technique is a suitable alternative aid to conduct a study of traffic safety. This research aims to conduct such study at four leg- signalized intersections using traffic conflict technique. Surveys include traffic conflict, volume data, spot speed and some geometric characteristics at four sites in Baghdad city. Rate quality control and cluster analysis are used to identify the hazardous approach and the abnormal conflict types respectively. Developed models show that, linear relationships are significantly appropriate to explain the relation between hourly traffic conflict and hourly approach traffic volume with coefficient of determination ranging between 0.701 and 0.884. Although this finding agrees with the literatures, exponential relationship introduces higher coefficient of determination between 0.759 and 0.897. This might be due to extra increase in conflicts at high traffic volume. Further, a model of multiple linear is appropriate to explain the relation between conflict rates and some of geometric characteristics with coefficient of determination ranging between 0.580 to 0.969. Identification of hazardous approach shows that, the lower rank in geometric characteristics among all approaches is the most hazardous one. This agrees with the finding in the developed model. In order to enhance traffic safety, the study proposes suitable countermeasures such as creating left turn lane, providing special phase for left-turn traffic. المستخلص

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