Abstract
One of the important points in the highway planning is that how the traffic volume will be assigned to road networks including roads to be newly constructed. In consideration of the road conditions, traffic conditions and transfer rule " traffic volumes the writer has set up models of simultaneous equations, and has probed into the assignment methods when two routes, the planned road and the existing competing road, are considered and also when more than two routes are the subject to be considered. The results of actual application of these models to several road networks, including a few toll road plans, indicated appropriate answers. The body is intended to report on the theory and application.