Development of a heavy-duty chassis dynamometer driving route

There is presently a lack of realistic driving cycles or schedules for the chassis dynamometer emissions testing of heavy-duty trucks. This research effort was motivated by the need for representative emissions measurement techniques to compare alternatively fuelled trucks with their diesel or gasoline counterparts operating in heavy-duty truck applications. Speed versus time and video recording data gathered from trucks in local delivery use were used to develop a city/suburban heavy vehicle route (referred to as the CSHVR) for Class 7 (11794-14969 kg gross vehicle weight) and Class 8 (14969-36287 kg) delivery trucks. Statistical data were gathered on actual truck driving behaviour, as well as 60 h of actual speed versus time driving information. A cycle was then developed by joining microtrips from the actual truck operation and verifying that it was representative of the whole database. A driving route was derived from this cycle with the help of the video data, and with the vehicle deceleration rates modified for practical reasons. It was found that a more powerful truck could bias its exhaust gas emissions by not aggressively applying full power while following a conventional speed versus time trace cycle. In comparison with a speed versus time cycle, a route allows sections of free acceleration (at full power) until a desired overall operating distance is met. A route is defined by a path that a truck must follow where driving instructions are dependent upon the acceleration of the truck, road conditions and speed limitations. The new route has been successfully employed in the emissions testing of several Class 8 tractors and was found to yield emission rates tin g/mile) that were higher than those for the previously documented WVU five-mile route (8 km in length) in the case of a Ford 36287 kg (80000 lb) GVWR tractor with a mechanically injected Cummins 261 kW (350 hp) engine.