The atmospheric pollution is one of the most important impacts of vehicular traffic; air pollution levels and the over-saturated traffic conditions constitute severe problems in many cities. A large number of models, with different characteristics, has been proposed in order to simulate traffic flow and related pollutant emissions. In this paper, a fuel consumption and pollutant emission model is presented, which has three interesting features. It is based on average traffic speed, and so it can be coupled with macro traffic simulators; its range of validity (1 - 30 km/h) is well suited for urban congested traffic; it reproduces consumption and emissions in presence of accelerations, decelerations, stop and go phenomena, typical of urban traffic. The model has been developed in three steps. Many experimental journeys have been effected by a test car in a large city (Naples); space and speed have been measured by every interval of 0.5 second. Fuel consumption and pollutant emissions have been computed second by second for each journey, using an instantaneous emission model, MODEM; afterwards, total fuel consumption and pollutant emissions in each journey have been computed. Statistical relationships between consumption/emissions rates (g/km) and average speed (km/h), observed in the test runs, have been derived by the least squares method.
