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Recent emission and field data from diesel particulate trap buses operating at the New York City Transit Authority (NYCTA) are summarized. As part of the NYCTA Trap Oxidizer Program, transient emission and performance test data were measured from a prototype diesel particulate trap system, which utilizes a Webasto in-line full flow diesel burner to periodically regenerate the ceramic monolith filter. In addition, the progress made during a large scale field test program of 398 new TMC RTS buses powered with Detroit Diesel Corporation (DDC) 6V-92TA bus engines equipped with Donaldson Company, Inc. (DCI) Dual Wallflow Monolith Electric Regeneration Trap System is presented. Discussion includes: trap system hardware and software issues, resulting trap system improvements, impact of the trap system on engine emissions and fuel economy, and potential trap monolith durability issues.

A diesel particulate trap system using two (2) monolithic ceramic filters and a diesel burner was designed for the 6V-92TA 2-stroke bus engine. The system comprises an electronic controller which controls four (4) valves to direct exhaust flow and burner heat flow. The exhaust passes through one filter, while trapped particulate is being regenerated in the other. The burner control sequence was optimized to avoid overheating of the system components and thermal shock of the traps. The system was tested for 100 hours in a test cell, using the New York Bus Cycle. Engine backpressure showed no noticeable increases from the baseline. The need to reduce particulate emissions from transit coach engines in the U.S.A. is driven by two forces.