Gap acceptance and rejection behavior and their impact on U-turn intersections and U-turn traffic simulation based on Vissim case study Najaf city

Generally, in general, there is significant traffic congestion at U-turn intersections, and during rush hour, many accidents are observed occurring at these intersections. This study is largely an engineering vision to clarify and evaluate some of the problems that occur at intersections, due to the impact of U-shaped intersections on how the road network operates and on traffic characteristics such as delay times and waiting lines. Some variables affect delays and accidents, such as the driver’s age and movements (driving behavior). Vehicle characteristics, driver aggression and speed, and speed of vehicles in the opposite direction. The probability of turning and the demand for it increase as the volume of traffic increases. The current study examines three locations of opposite intersections in the city of Najaf, located 160 kilometers (about 100 miles) south of Baghdad. The study relied on evaluating the operational performance of intersections in terms of accepting and rejecting gaps, delays, and driving behaviors that may cause many accidents, delays, and traffic congestion. The results showed the critical gap values of 4, 3, and 3.3 seconds, in addition to a follow-up time of 3.1, 3.3, and 2.7 seconds, respectively. The delay times were 9, 7, and 8, respectively. Studies conducted on intersections in the opposite direction show their importance in traffic operations and traffic safety. Movement volumes were also studied and simulated using the Vissim program and calibrated to determine the extent of the difference between the data obtained from the sites under study and the data extracted from the program. The data collection method was video photography, where a video camera was placed 50 meters from the turning hole to obtain accuracy. Sufficient and clear vision for collecting the required data.