Abstract
The project evaluates the relationship between traffic delays and vehicle conflicts to explore if traffic conflict techniques can be used to assess the performance of roadway systems. Seven signalized intersections located in the Sacramento area were selected on the basis of geometric similarity, signal timing, and traffic characteristics. The morning peak hours of 6:30 a.m. to 10:00 a.m., Monday through Thursday, were chosen to collect traffic conflict and volume data for this study. Signal timing and phasing for the seven selected intersections were obtained from the Departments of Transportation of the County of Sacramento and the City of Sacramento. The geometric characteristics of the selected sites were acquired from Google Earth. A review of previous research was conducted to identify the best methodology for this study. The peak-hour traffic volume, signal timing, and geometry of the intersections were entered into Synchro traffic analysis software. The resulting output was the average delay data for all seven intersections during the study period. A regression analysis was conducted to assess the correlation between intersection conflicts and average delay. The study found that individual movements show an inconsistent relationship between conflict and delay. The study revealed significant relationships between left movement conflicts and left movement delay, and slow vehicle movement conflicts and through movement delay. In contrast, the study found insignificant relationships between right movement conflicts and right movement delay, and lane change conflicts and through movement delay. The relationship of total number of conflict and total delay also show insignificant relationship with a coefficient of determination (R2 = 0.04), which suggests that the total number of conflicts explains only 4 percent of the total variation in delay. As a result, it was determined that traffic conflict techniques alone cannot be used as a good proxy to assess the level of service of signalized intersections.