Abstract
The gridlock phenomenon in this study is defined as a condition in which a traffic queue forms all around a single grid (rectangular shape) road network and it causes a capacity reduction of the network without external intervention by the influence of downstream traffic queue on the throughput of an intersection of the network. When an isotopic condition is assumed, there are two resulting states after a traffic queue is formed all around a single grid network. On the other hand, one more traffic state can occur in an anisotropic condition. They are determined by the relationship between two parameters; the proportions of remaining traffic which makes right turn at the downstream intersection to the link traffic volume and the merging ratio of the downstream intersection. Furthermore, the proportion of remaining traffic at the downstream intersection to the link traffic volume changes in response to the traffic state of the link. In consideration of this transition under an anisotropic condition, the possibility of the occurrence of the phenomenon that the traffic flow suddenly falls and goes to deadlock, even though the traffic flow does not decrease when a traffic queue is once formed all around the network is indicated.
