Study of Classic Traffic Assignment Application for Urban Transportation

One of the complicated steps in transportation planning involving a large amount of mathematical calculations is traffic assignment for which, some heuristic methods have been devised. Incremental traffic assignment method, despite its low accuracy, is considered due to its simplicity and much less calculations. In this Paper, the assumption of equal step size in the traditional incremental traffic assignment is relaxed, showing that with intelligent variable, partitioning the demand in the different steps of the algorithm, the accuracy of the method will increase. The proposed algorithm is applicable the city of Mashhad as a real sized case study showing an increase in the accuracy of results and decrease in amount of calculations and related time. Results indicate that for a certain number of iteration, the appropriate solutions accrue when the other steps have the least variation size. Also, a leaner relation is observed between the number of the iteration and first step size. The main advantage of this technique is that it can provide a simple and economical method for traffic assignment as compared with user equilibrium in which R2 for that is equal to 0.57and for a stochastic assignment is equal 0.53.