Speed frequency distribution in air pollutantsʹ emissions estimate from road traffic

The work discusses the aspects linked to the speed in the application of the CORINAIR methodology to urban areas. In particular, the introduction of a speed frequency distribution (in thirteen classes with range 10 km/h) by vehicle category is discussed. A study on sensitivity finalized to the analysis of the influence of speed on the emissions is presented. Many cases are examined in which, keeping the average speed constant, a different speed distribution is introduced. The estimates obtained through the simulations are compared with those obtained using a single average speed. The result is that a deeper knowledge of driving characteristics and speeds is essential to understand means of the estimates for those pollutants whose emission dependence on speed is strongly non-linear.