Analysis and Modeling of Delay Time for Turbo and Modern Roundabouts

Today, turbo and modern roundabouts are the effective commonly alternatives for controlling urban at-grade intersections which are used to improve traffic conditions and delays. Because of their geometric features in selecting way and the right of way for drivers, they have better efficiency than signalized intersections. In the beginning of this study, in order to evaluate the effectiveness of turbo and modern roundabouts in reducing traffic volume, increasing capacity and also examine traffic effective parameters (radius, lane number, speed and traffic flow)), Aimsun software  was used for simulating. And then by using Surface Response, Hessian Gradient Methods and Genetic Algorithm, a mathematical relation for estimating delay time in turbo and modern roundabouts in condition of non-traffic signal control was suggested. The obtained results from this research indicate that the mixed methods of surface response – Hessian gradient and surface response- genetic algorithm are more accurate than other methods. Therefore, the obtained delay logarithm relations according to the input variables (traffic flow, speed, lane number and radius) could predict delay in turbo and modern roundabouts with proper accuracy in non-traffic signal control conditions in which these relations have acceptable sensitivity accuracy.