Evaluation and Technical Analysis of U-Turns with Emphasis on Traffic Parameters Using Aimsun Software (Case Study: Two U-Turns of Chamran Highway in Tehran)

Nowadays, the problem of traffic in many cities of the world has occupied a major part of the time and energy of the citizens. The U-turn is used as one of the elements of the urban road network in many cases to create access between the roads on both sides of an arterial route with a middle separator. In order to reduce the traffic in the desired sections, which are located in Chamran highway and in Tehran city as a case study, geometric modification will be done and the basic question will be answered whether the geometric modification of the desired U-turns can have an effect on the traffic parameters? Necessity of geometric correction: reduction of heavy traffic, increase of travel safety, reduction of delay time and in general non-optimal use of travel facilities are the necessity of conducting this research. In this research, the desired U-turns are modeled in Aimsun software, then the modeled U-turns are subjected to different traffic volumes at different hours, considering scenarios such as: 1.increase of half lane 2.Non-level intersection (overpass design) 3.The design of the jug handle U-turn and after the software calibration, the software outputs were extracted. Finally, traffic analysis of the desired section is performed using the outputs of Aimsun software for the indicated indicators. Software outputs play a decisive role in choosing the optimal plan. The results of the simulation showed that the design of the U-turn type B and non-level intersection, has a significant effect on improving traffic effects, which on average reduces the time in traffic by 67% and 81% , increases the speed of vehicles by 10% and 15%, and decreases by about 27% and 30% of the time traveled.