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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.

Progress is reported on a project sponsored by the California Air Resources Board (ARB) to evaluate the potential of diesel particulate trap systems for retrofit application to reduce emissions from buses and trucks. A trap system was selected for evaluation based on availability of commercial prototypes at the time of the project. Engine dynamometer testing of this trap system is reported over advanced design bus cycles. The results showed that the system is viable for application to a bus equipped with a Detroit Diesel Corporation 6V-92TA diesel engine, producing satisfactory exhaust backpressure and emission characteristics over a 500 hour test period. Field testing of this system on a transit coach is now ongoing at Southern California Rapid Transit District (SCRTD) and the experience is reported. Emission testing has been conducted regularly at ARB to verify the performance of the trap system.