The accuracy of the traffic assignment process when capacity restraint is used in the urban transportation planning process was evaluated. A brief explanation of the capacity restraint procedure is given to provide the needed background information. Data obtained from 10 urban transportation studies are used to evaluate the adequacy of the traffic assignment process to match existing travel pat- terns. This evaluation is made on the basis of five tests which measure the differences between ground count volumes and assigned volumes. The results of the evaluation indicate that the traffic assignment process can match ground counts within plus or minus 15 percent on links carrying volumes greater than approximately 5,000 vehicles. The most accurate results are obtained by using the average assigned volumes from three or four iterations of capacity restraint. (Author/publisher)
Abstract