Modified HCM Method for Delay Estimation at Unsignalized T- Intersections: A Case Study from Delta Region, Egypt

This study proposes a modified gap acceptance method to estimate control delay at unsignalized intersections in Egypt. The Highway Capacity Manual (HCM) method for estimating control delay at unsignalized intersections assumes that all lower-ranking movements yield completely to higher-ranking movements. However, this assumption may not be valid in Egypt, where drivers in lower-ranking movements sometimes violate right-of-way. The proposed method introduces an adjustment factor to account for the amount of real priority that higher-ranking movements actually get from lower-ranking movements. The adjustment factor was developed based on data collected from three un-signalized T-intersections from Mansoura and Damietta cities in Egypt. The results showed that the proposed method produces relatively similar results to the observed intersection delay, with a relative difference between +0.64 and +7.31%. In contrast, the unadjusted HCM method produces a relatively high difference in the intersection delay (+1.83 and +84.59%) compared to the observed delay.