U-turn Waiting Time Estimation at Midblock Median Opening

Abstract

The u-turn traffic at midblock median opening has to wait for the acceptable headway of conflicting through traffic stream. This research proposed the waiting time estimation by spreadsheet simulation. The spreadsheet software generated random headway size according to the known statistic distribution. The randomly generated headways were compared with the critical headway, which is assumed to follow the log-normal distribution, to determine whether the u-turn vehicle accepts the headway. The data was collected at a midblock median opening in order to evaluate the estimation result. The results showed that the proposed method can estimate the waiting time well when the through traffic volume is not large. When the through traffic volume is large, the collected waiting time is much lower than its estimated value. The result implied that the u-turn drivers became impatient while waiting for a long time and conducted the unsafe forcing u-turn maneuver.