Traffic Assignment in Practice: Overview and Guidelines for Users

Abstract

This paper presents an overview of the elements of traffic assignment and a synthesis of the problems that may be encountered in applying traffic‐assignment models in practice. The elements include preparing the transportation network, establishing the origin‐destination (OD) demands, identifying a traffic‐assignment technique, calibrating and validating a model, and forecasting. The practical problems of traffic assignment are classified into four categories: network‐representation problems, system‐subarea data‐translation problems, model‐calibration problems, and forecasting problems. The paper presents the state of the art in traffic‐assignment elements and provides specific guidelines on their implementation in practice and on the resolution of the identified problems. This paper is one of a series being produced by the Urban Transportation Division (UTD) Transportation Planning Committee of ASCE.