DEVELOPING A SET OF FUEL CONSUMPTION AND EMISSIONS MODELS FOR USE IN TRAFFIC NETWORK MODELLING

This paper introduces the results of a research project on the pollutant emissions and fuel consumption characteristics of mixed traffic streams under different levels of congestion. The project involved extensive testing of a number of vehicles, both on-road and in the laboratory, to determine their fuel consumption and emissions characteristics under different traffic conditions. A set of models for different vehicle types were then assembled, based on the hierarchical family of models for fuel consumption presented by Biggs and Akcelik (1986), which was also capable of describing vehicle emission rates. The model family consists of models at four levels, from an 'instantaneous' model for individual vehicles driven in traffic, through an 'elemental' model suitable for studies of intersection behaviour, a 'link' model suitable for transport network analysis, and a 'journey' model suitable for land use planning applications. The models for individual vehicle types may be combined to yield models for the performance of a traffic stream. These models may then be incorporated into transport network analysis performance, as tools for use in the prediction of environmental and energy impacts of road transport projects. One such integration of the models into a super-model (IMPAECT) for environmental impact analysis of transport planning decisions is described. The focus is on the development and application of the energy and emissions models, which are made up of three sub-models: (1) traffic stream composition sub-models, to determine the emissions or fuel consumption of a traffic stream as an aggregate of the vehicles in that stream, (2) congestion functions, to relate travel conditions (delays, queuing and speed-time trajectories) to traffic flows on particular types of roads, and (3) sub-models of vehicle energy and emissions performance under different traffic conditions. (A) For the covering abstract see IRRD 886400.