Parallel Traffic Flow Simulation of Freeway Networks: Phase 2

Explicit and implicit numerical methods for solving simple macroscopic traffic flow continuum models have been studied and efficiently implemented in traffic simulation codes in the past. We have already studied and implemented explicit methods for solving the high-order flow conservation traffic model. Implicit methods allow much larger time step size than explicit methods, for the same accuracy. However, at each time step a nonlinear system must be solved. We use the Newton method coupled with a linear iterative method (Orthomin). We accelerate the convergence of Orthomin with parallel incomplete LU factorization preconditionings. We implemented this implicit method on a 16 processor nCUBE2 parallel computer and obtained significant execution time speedup.