Distributed Simulation of Freeway Traffic Flow Using Personal Computers

Abstract

This article presents a personal computer (PC)-based distributed simulation methodology applicable to real-time estimation of time-variant parameters in freeway traffic flow. The method uses the interprocess communication procedures currently available under Windows NT and adopts 2 types of distributed computing architectures. The proposed method, based on macroscopic traffic models developed and tested in prior studies, first divides a given freeway into a set of subsections depending on the number of available processors or PCs. At every time step, each processor simulates its own subsection and exchanges the internal boundary data with another processor that simulates the adjacent subsection. The performance of the parallel algorithm was compared with that of a single-processor-based sequential simulation using 2 different types of hardware configurations: a network of 2 PCs and a dual-processor PC. Test results with the 2-PC network parallel system showed a speedup of 1.94 over the sequential simulation with a single PC for the 1-hour simulation of a 20-mile freeway section. The speedup for 1-hour simulation of an 80-mile section was increased to 1.96 with 2 processors, which is close to the ideal speedup. Performance tests with the dual-processor PC resulted in consistent, but not significantly faster, execution than those with the 2-PC network, indicating the feasibility of developing a practical on-line decision support system with a network of PCs for freeway operations.