A solution algorithm based on circuit simulation for the traffic assignment problem

A key process for urban transportation planning, the traffic assignment problem (TAP) determines the route choice of travelers and the flow of a traffic network. Under the user equilibrium (UE) condition, the travel costs of the chosen routes are identical for each origin-destination pair. The resulting UE flow bears significant resemblance to an electronic circuit. In particular, if the electrical current is viewed as the traffic volume, the voltage drop can be thought of as the travel time. Based on the fundamental idea “let electrons simulate travelers,” this study develops a TAP solution algorithm that iteratively solves the associated sub-problems based on electronic circuit simulation. Numerical experiments are performed to illustrate the key techniques used in developing the solution algorithm and to compare the performance with the classic Frank-Wolfe Algorithm. The solution approach based on circuit simulation is found to be a promising alternative to determine the UE flow of the TAP, and it has been used as the core algorithm of a prototype microprocessor system.