Simple Practices of User Equilibrium Traffic Assignment
This tool has been developed as a simple interface for practising User Equilibrium Traffic Assignment. The ‘Algorithms’ page contains several traffic assignment algorithms, their parameters and performance indicators. These algorithms are run on a simple test network with 2 nodes, 2 zones and 2 links (below image) to perform the tasks. Since there are only two links, there was no need to integrate a ‘Shortest Path’ algorithm. Instead, it operates with a simple rule logic. For the two zones defined as A and B, the flow is only from A to B. The BPR formulation is used for the volume-delay relationship. All parameters in the application are as follows; total demand, BPR function coefficients, link capacities, free flow travel times of links, total iteration, and demand coefficient for the decremental algorithm. On the ‘Algorithms’ page, you can change the parameter values and compare the algorithm responses and their performances.
"Decremental Assignment" is an algorithm I added for this application. It works in the reverse logic of the Incramental Assignment technique. If you determine the demand coefficient correctly, it provides user equilibrium conditions with high consistency... However, I do not know its place in the literature yet. Moreover, I plan to add more algorithms to this tool in the future, such as; Stochastic User Equilibrium, All or Nothing, Capacity Restraint Assignment, System Optimum...
I hope you enjoy using the application :)
