Abstract
This paper illustrates the approach, the experimental work and the preliminary results of a research aimed at devising a comprehensive procedure for the evaluation of pollutant emissions from cars in the city of Milan. The activity described herein focuses on two objectives: characterise the ensemble of cars actually circulating and define a method to estimate their emissions under real driving conditions.
The distribution of car characteristics (type, model, displacement, age, mileage) was estimated based on data collected from the Italian national car registry, from experimental observations of the vehicles passing a key intersection of the city and from a survey of the cars inspected in 1999.
The method pursued for the estimation of emissions assumes that at each instant they can be directly correlated to the main parameters describing the motion of the vehicle - velocity, acceleration - or those describing the engine conditions - speed of revolution, power output. Emission maps giving emissions vs. vehicle kinematic parameters (or vs. engine conditions) have been evaluated by testing a sample of 27 cars at the roller dynamometer of the Agip laboratories in S.Donato Milanese. To achieve acceptable accuracy of transient measurements (concentrations and flow rates were measured at a frequency of 1 Hz) it was necessary to introduce significant refinements to the experimental apparatus and to post-process the data recorded during the tests.
The preliminary results obtained so far do not give conclusive evidence on the feasibility and the potential of emission maps. Nonetheless, there are positive indications which, if confirmed by further experimentation, could substantially simplify the estimation of emissions and pave the way to the design of more environmentally benign traffic regulations.