An estimation method of OD matrix in non-congestion ring expressway

In order to obtain the real-time traffic flows between on-ramps and off-ramps of the ring expressway, a model to estimate the OD(origin-destination) matrix with consideration of the structural characteristics of the ring expressway is proposed in this paper.The ring expressway is looked as a loop network, without considering traffic congestion,the distance fromthe on-ramps to off-ramps that drivers may choose is not exceeding 1/2 of the loopperimeter. According to this principle, we use on-ramps’ flows to express mainline sections’ and off-ramps’ flows. These expressions form the simultaneous equations which can be solved with Gaussian Elimination, and the flow proportions between on and off-ramps (OD matrix) can be achieved. The propose method is applied to Xi’an Ring Expressway, the OD matrix is extracted from the estimated flow proportions between on and off ramps, and is compared with the actual survey. The model is verified to be feasible.