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Growing concern about energy conservation and exhaust gas emissions from heavy duty engines of trucks and buses has increased the demand for the use of alternate fuels. A unique transportable testing laboratory designed to measure specific constituents of exhaust gas emissions from the engines of heavy duty vehicles operating on conventional or alternate fuels has been constructed by a team from West Virginia University. In this transportable facility, a special flat-bed trailer has been constructed to accommodate drive train units, free-rotating rollers, power-absorbing units to simulate road load, and flywheels to simulate vehicle inertia. Four hydraulic jacks are used to lower it to the ground at the fleet site. This allows the tested vehicle to be driven onto rollers embedded in the flat-bed. Hub adapters are connected at the outboard wheel locations at each side of the drive shaft of the vehicle.

A correlation study of vehicle exhaust emissions measurements was conducted by the West Virginia University (WVU) Transportable Heavy-Duty Vehicle Emissions Testing Laboratory and the Los Angeles County Metropolitan Transportation Authority (MTA) Emissions Testing Facility. A diesel fueled transit bus was tested by both chassis dynamometer emissions testing laboratories. Exhaust emissions were sampled from the tested vehicle during the operation of the Federal Transit Administration (FTA) Central Business District (CBD) testing cycle. Data of gaseous and particulate matter emissions was obtained at each testing laboratory. The emissions results were compared to evaluate the effects of different equipment, test procedures, and drivers on the measurements of exhaust emissions of heavy-duty vehicles operated on a chassis dynamometer.