Simultaneous measurements of gaseous emissions, particulates and noise from individual vehicles in traffic

In order to identify vehicles and traffic situations that have a negative impact on the environment, it is important to be able to measure emissions from individual vehicles in traffic. In this study an attempt is made to measure gases, particles and noise emitted from single vehicles in normal traffic. An apparatus for Fuel Efficiency Automobile Test (FEAT), by which emissions of NO, CO, HC and CO2 are measured, was combined with particle instruments for both total and size-distribution measurements, as well as noise measurements. The sampling of particles was done utilising a tube system for sampling on the road together with a dilution system. The noise measurements were done with two microphones at different heights. The measurements show that it is feasible to study regulated emissions, particle emissions and noise emissions from individual vehicles in normal traffic. Noise data was collected from ca 200 individual vehicles during the measurement campaign and the emissions of some of the vehicles were evaluated. The measurements were manually supervised and the evaluations mainly made by hand. The experiences of this project are encouraging and show that it is possible to perform measurements of noise emissions from individual vehicles automatically. One way to achieve this would be by extending the FEAT system so that it also measures noise emission. Further it is important to perform sampling and evaluation automatically and to use computerized procedures for the evaluation. By using CO2 data together with the particle data, we were able to obtain PM emission factors for individual vehicles. We also showed that the particle size-distribution can be obtained from individual vehicles in traffic when using a fast instrument. This also, in principle, allows for the separation of particles emitted from the engine and particles from road and tyre wear. The results show that the emissions of particles vary significantly from vehicle to vehicle. A variation range of two orders of magnitude (between 8.5 x 1011 and 1.2 x 1014 part km 1 veh 1) has been observed. The FEAT systems together with a system for speed and acceleration monitoring, were able to record how the emissions of NO, HC, CO and CO2 depend on speed and acceleration. A general conclusion is that after some further improvement the setup should suitable for more systematic mapping of vehicle tailpipe and noise emissions. Further, the system may be used for identifying individual vehicles that can be considered large emitters

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