1 Emission Factors for HDV and Validation by Tunnel Measurements Stefan Hausberger, Johannes Rodler, Peter Sturm, Martin Rexeis Institute for Internal Combustion Engines and Thermodynamics, Graz University of Technology, Austria Email: haus@vkma.tu-graz.ac.at Abstract The paper describes a Heavy Duty Vehicle (HDV) emission model developed within the framework of three international projects. Model input data was gained from extensive measurement campaigns on HDV engines and HDV and a European data collection program. The paper presents the model and resulting emission factors for HDV. These new emission factors were compared with the values given in the actual version of the Handbook Emission Factors 1.2 (Keller, 1998). Road tunnel measurements were used to validate the new model. Keywords Heavy Duty Vehicles, emission measurement, emission factor modeling 1 Introduction In the German- Austrian- Swiss cooperation (D.A.CH.) the “Handbook of Emission Factors for Road Traffic” was established in the 90 s , e.g. (BUWAL, 1995). While emission functions for Light Duty Vehicles (LDV) have been updated with measurements regularly, the Heavy Duty Vehicle (HDV) emission values for Europe are still based on measurements of engines constructed between 1984 and 1990 (Hassel, 1995). Thus an update of the emission functions with measurements of new HDV and their engines as well as an improvement of the general methodology were absolutely necessary. This update started in 1999 while two other major activities on HDV emission modeling had their starting point in 2000. These are the EU 5 th research framework program ARTEMIS / Work Package 400 (http://www.trl.co.uk/artemis/introduction.htm) and the COST 346 initiative (http://www.cordis.lu/cost-transport/src/cost-346.htm).