J. Barceló, E.Codina and D. García

EMME/2 European Users Meeting, June 2002

Abstract

The interest in interfacing Macroscopic models for transportation analysis with Microscopic models raised time ago as a consequence of the requirement for a deeper analysis in transport planning where the long term views proper of planning applications had to be combined with short term views on the potential impacts of the alternative designs when subject to the time dependent variability of the demand. Interfacing a macroscopic model of a road network , as for instance one built with EMME/2, with a microscopic model as for example one built with AIMSUN requires a very specific methodology to ensure the consistency of the network representations at both levels, the correspondence of the demand structure (i.e. centroids and connectors), and a coherent exchange of information between the two levels. This problem was addressed in a paper presented at the 9th European EMME/2 User�s Group Conference held in Barcelona in 2000.

There has also been another reason to improve the exchange of information between the two approaches at the level of Origin-Destination matrices. The current trend in microscopic traffic simulation is based on a new paradigm in which individual vehicles travel from origins to destinations along the available paths according to route choice models, paths are timely updated according to changes in traffic conditions on the road network. Strictly speaking this means that time-depend origin-destination matrices have to be supplied as input to the microscopic simulator. The theoretical approaches developed so far to estimate dynamically origin-destination matrices are suitable only for very specific types of road networks, i.e. linear structures as in the case of freeways and motorways, in which the only origins and destinations are the on and off-ramps. Unfortunately these approaches do not work in the case of true network structures and even less when networks are of a sensible size as it is the case with the real life applications. A quick and dirty solution to this problem could be based in manipulating the Origin-Destination matrices using information from OD surveys, if available, to timeslice the global OD matrices, extract the local OD matrices (traversals) for the smaller areas to be analysed microscopically, and adjust these matrices on basis to the link flow counts of the subnetwork spanning the area of interest. The methodology proposed in this paper is based on the features and functions supported both by EMME/2 and AIMSUN to assist the analyst in automatically generate the EMME/2 model from an AIMSUN model, graphically select the subnetwork of interest, generate the traversal, adjust the traversal and import the adjusted traversal matrix into the AIMSUN model of the subnetwork to perform the simulation experiments of interest.

The Scenario Analysis System is a graphic software platform that embeds the microscopic traffic simulator AIMSUN, and interfaces EMME/2, providing the analyst with a friendly user interface to perform the above described operations. The Scenario Analysis System can be used for detailed planning analysis as well as for strategic analysis to support traffic management policies in specific scenarios. This paper describes the methodology, the structure of the system and a demonstration of how it works. The demonstration is based on the models built to support traffic management on the road network consisting of the motorways and main highways of the Land of Hessen in Germany.

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