New vehicles introduced on the market are designed to meet standards ruled out by legislations and directives. The regulatory system for certification of HD engines is focusing on the engine instead of the vehicle. Gradually when requirements will be tightened more sophisticated emission control systems will be introduced, and thereby questions could be raised whether real life emissions from late technology vehicles in normal operation are different from those achieved during well controlled laboratory testing of an engine. Technology to carry out high quality testing on-road is developing and the use of portable emission measurement systems (PEMS) will play an important role for establishment of real life emission factors as well as to verify whether engines meet the set standards. Since many years AVL MTC has been working with correlation between chassis dynamometer testing and engine testing. In 2004, the program was extended to also include the use of PEMS and testing vehicles on-road. In Sweden a national program, financed by the Swedish Road Administration, for in-use service testing of HDV is in place since 2006 and additional activities are ongoing for development of "real life" emission factors and validation of emission performance from late engine technologies (e.g. SCR, EGR). The results from testing underline that there are differences in emission behavior when vehicles are tested on-road in normal operation compared with testing engines/vehicles for certification purposes. There are cases when engines/vehicles are meeting set standards while testing the same vehicle on-road show 5 - 10 times higher results. Such a difference might result in severe underestimation of emissions emitted to the atmosphere.

16th International Symposium Transport and Air Pollution 2008, Graz