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The simulation of U-turns is currently of great interest to many transportation professionals due to the widespread use of indirect driveway left-turn treatments. In this study, a procedure was proposed to help transportation professionals model U-turn movements at unsignalized intersections with nontraversable median cross sections in the traffic simulation program VISSIM. The behavioral features of U-turning drivers, such as the priority rule, lane selection, and turning speed of U-turns, were determined using data collected from 13 different locations. A procedure based on a genetic algorithm was proposed to calibrate and validate the VISSIM simulation model. The simulation results of the calibrated VISSIM model were compared to field measured capacity and to the capacity estimated using gap acceptance models developed in previous studies. The calibrated VISSIM simulation model yields mean absolute percent errors of 17.6 and 20.7% for four-lane and six-lane streets, respectively. The results show that VISSIM provides reasonable capacity estimates for U-turns at unsignalized intersections with raised median cross sections, after crucial parameters are properly defined and calibrated. [ABSTRACT FROM AUTHOR]

Traditional pedestrian level of service measures at signalized intersections are based on pedestrian space and pedestrian delay. However, these measures may not adequately reflect the negative impact of right-turning traffic on pedestrians. This paper presents a statistical analysis using a binary logit model that provides new insights into the factors that affect the likelihood that a pedestrian is compromised (delayed, altered their travel path, or altered their travel speed) in response to traffic turning right (on green) during concurrent vehicle/pedestrian signal timing. The statistical analysis indicates that a number of factors affect the likelihood of a pedestrian being compromised including pedestrian direction of travel, right-turn traffic volume, number of pedestrians crossing, whether the pedestrian arrived late and began crossing after the end of the walk interval, and the crosswalk characteristics including location (downtown versus suburban) and one-way/two-way streets. [ABSTRACT FROM AUTHOR]