CORSIM-based simulation approach to evaluation of direct left turn vs. right turn plus U-turn from driveways

Right turn plus U-turn at the median as an alternative of direct left turn has been considered an important issue in access management treatment. The motivation behind using this strategy comes from the consideration of safety as well as from operation performance. The objective of this study is to evaluate the operational performances of direct left turn and right turn plus U-turn through simulation. This study attempts to figure out under what traffic conditions it is worth replacing direct left turn into right turn plus U-turn from operational point of view. CORSIM, a combination of FRESIM and NETSIM, was selected as the analytical tool in the study due to its strong capability of road network evaluation and animation display function. The delay and travel time were used as the measures of effectiveness (MOE) in evaluating the operational performance of direct left turn (DLT) and right turn plus U-turn (RT+UT).; In order to achieve the objective of this study, field observation was conducted to collect necessary data. From simulation point of view, the purpose of collecting the field data is for the calibration of the models. For the first time, a huge amount of gap acceptance data for the turning movements were collected at the field in order to look into the operational performance of each turning movements related to DLT and RT+UT. A specifically designed computer program was developed to help collect gaps data from the field.; The site-specific simulation models for the eight locations were developed using CORSIM. Each model has been calibrated based on the field data. The comparisons between DLT and RT+UT in terms of the delay and travel time have been conducted under different levels of traffic volume. Besides, the general simulation model was also developed. This general simulation model was calibrated using the average data of these locations.; The regression models of delay and travel time for DLT and RT+UT were developed to quantify the relationship between the delay (travel time) and the explanatory variables. In addition, the before and after analysis based on the simulation data was conducted to compare the system delay and system travel time under the given conditions.