Traffic assignment by trip type using volume restraint and link restraint for application in small urban areas

Abstract This research involved the development of a new traffic assignment model consisting of a set of procedures for an urbanized area with a population of 172,000. Historical, social, and economic data were used as input to conventional trip generation and trip distribution models to produce a trip table for network assignment. This fixed table was divided into three trip types: external‐external trips, external‐internal trips, and internal‐internal trips. The methodology used to develop the new traffic assignment model assigned each of the trip types by varying the diversion of trips from the minimum path. External‐external trips were assigned on a minimum path routing and external‐internal trips were assigned with a slight diversion from the minimum path. Internal‐internal trips were assigned with more diversion than external‐internal trips and adjusted by utilizing iterative volume restraint and incremental link restraint. A statistical analysis indicated that assigning trips by trip types using trip diversion and volume and link restraint produces a significant improvement in the accuracy of the assigned traffic volumes.