Recalibration of a vehicle power model for fuel and emission estimation and its effect on assessment of alternative intersection treatments

Abstract

Estimation of fuel consumption and pollutant emissions for evaluating road traffic conditions is useful for environmental assessment in traffic design, operations and planning. This also forms the basis of operating cost modelling. Fuel consumption and emission (CO2, CO, HC, Nox) models with four levels of aggregation for traffic engineering and transport planning purposes were developed by the first author and his colleagues at the Australian Road Research Board in the 1980s. These models are based on vehicle power requirements, and the four-mode elemental (modal) and the more detailed instantaneous forms of the model are implemented in the SIDRA INTERSECTION and SIDRA TRIP software packages. This paper describes the recent work on recalibration of light and heavy vehicle parameters used by this model using a large empirical database for a modern vehicle fleet. Implications of the change in fuel and emission model parameters on intersection assessment are considered. A roundabout evaluation case is presented assessing the effectiveness of roundabout metering signals using the fuel consumption and emission models with (i) older vehicle parameter values and (ii) the recalibrated parameter values to investigate whether the changes in vehicle parameters change the results significantly. The model provided in the SIDRA INTERSECTION software package is used for this purpose.