Comparison of measured and calculated motorway emission data

A comprehensive field campaign was carried out to check the quality of mode lled on-road emissions of NOx and CO by comparing them with real-world emis sions on a motorway in the southwestern part of Germany. Three different se ts of emission data were determined for a section of the motorway A 656 tha t connects Mannheim and Heidelberg. First, emission data were pre-calculate d, that means before the field campaign took place, using literature data f or traffic volume. types of vehicles and driving speeds. Second, detailed t raffic measurements during two intensive measurement phases were used to ca lculate improved emission data based on the actual traffic situation. Third , real-world emission data were determined by meteorological and chemical m easurements. It shows that the differences of the pre-calculated emission d ata and the emission data improved by the traffic measurements differ by le ss than 15% in case of CO and approx, by 35 % in case of NOx. A comparison of the observed emissions with the calculated ones gives an agreement for N Ox within the error bars. For CO, however, a discrepancy by a factor of two was found. The real world emissions were much higher than calculated. (C) 2000 Elsevier Science Ltd. All rights reserved.