Verification of traffic emission factors using measurements in a short tunnel in the Czech Republic

Road transportation activities are major contributors of nitrogen oxides emissions to the air. The impact on the growth of NOx emission levels is found to be strongly correlated with the traffic intensities on highways. Various types of emission models performing emission assessment of traffic-related pollutants have been developed, but few of them were developed by using real-world measurements of NOx concentrations in ambient air. The most convenient sites to perform measurements in real-world conditions are road tunnels. This paper presents a comparison of HBEFA model NOx emission calculations and NOx emission measured in a short tunnel in the Czech Republic. Simultaneously, measured time-resolved NOx concentration and traffic activity counting were performed in the Zeleny most tunnel in the Czech Republic. The experimental work yielded reliable results of the mutual correlation of NOx level and traffic intensity in the tunnel section with statistical evidence. Emission factors from HBEFA emission model for road transport were applied and compared with the results from several measurement campaigns in the Czech Republic. It was found that calculated NOx emissions differed from measured NOx emissions due to the overestimation of light vehicles emissions and underestimation of high-duty vehicles emissions.