Freeway OD matrices estimation with on/off ramps traffic counts

This paper analyzed the relationship between OD matrices and on/off ramps of freeway, and built the freeway ramp flow relation model and freeway ramps system state space model. Based on analyzing the characters and constraint conditions of OD matrices, this paper applied the constrained Kalman filter(CKF) to estimate OD matrices. Simulation results indicate that CKF method performes much better than traditional Kalman filter(KF) , and the output can trace time-variable OD matrix well. 1 tab, 9 figs, 11 refs.