A methodology for private transportation planning assessment: GETRAM environment, an application to Barcelona's metropolitan area

Abstract

Traffic assignment models based on the user equilibrium approach are one of the most widely used tools in transportation planning analysis. Based on Wardrop’s, principle as a behavioral principle modeling the route choice process, they lead to a nice mathematical model for which there are efficient algorithms that provide solutions in terms of the expected flows on network links. Resulting flows offer a static average view of the expected use of the road infrastructure under the modeling hypothesis. This information has usually been enough for the planning decisions. However, the evolution of advanced technologies and their application to modern traffic management systems require in most cases a dynamic view complementing the static estimates provided by the assignment tools. The planned infrastructure is probably sufficient for average demand, but time-varying traffic flows, i.e. at peak periods, combined with the influence of road geometry, can produce undesired congestion that can not be forecasted or analysed with the static tools. There is a clear case for a change in the analysis methodology such as combination of a well known traffic assignment tool, the EMME/2 model, with a microscopic traffic simulator, the AIMSUN2 (Advanced Interactive Microscopic Simulator for Urban and Non-urban Networks) which this paper proposes.