Cleaning up the existing diesel engine fleet to reduce diesel emissions and public’s exposure risk remains a challenge and opportunity in New York State (NYS) and across the country. While much attention and work has been focused on new emission reduction technology development and certification, very little has been done to design and examine the operations of diesel retrofit deployment projects/programs, which play a critical role in achieving cost-effective diesel engine clean-up. Efficient retrofit devices need to be identified according to specific diesel engine characteristics/duty cycles and used in the right application. Even with good certified retrofit technologies, unwise decision in the operations and deployment of a retrofit program could significantly limit the benefit. The New York State Department of Transportation (NYSDOT) is mandated by law to retrofit many of its existing 7000 pieces of diesel vehicles/equipment (between 1 and 30 years old) in all classes and sizes with “Best Available Retrofit Technology.” While the benefit of retrofitting the NYSDOT diesel engine fleet is significant, the investment needed is also sizable. To meet such a challenge with limited funds and other operational constraints, cost-effective technologies, feasible emission reducing practices and guidelines, and well-designed NYSDOT deployment programs are all crucial. Optimizing diesel retrofit deployment is a difficult undertaking for State program and project managers; but the right combination of diesel retrofit decision supporting information systems and practice guidelines will lead to an improvement in the program’s overall effectiveness.

To provide the NYSDOT and potentially other state and local diesel vehicle operating agencies with the most useful scientific and empirical information for cost-effective diesel emissions reduction, we propose a comprehensive and systematic study of diesel retrofit targeting the NYSDOT diesel engine fleet. Key information factors to consider in the study will include a diesel engine fleet inventory database with detailed parameters pertinent to retrofit emissions, duty/driving cycles of different categories of diesel engines/vehicles, a fund allocation and engine selection methodology that takes into account all relevant restricting factors, a rigorous retrofit deployment procedure, cost-benefit analysis, and careful after-retrofit performance tracking system and database. Especially, in searching for diesel cleanup strategies, it is essential to bear in mind three key issues: 1) upgrades will not have the same effect on all vehicles. In particular, older vehicles may experience a greater emission reduction from an upgrade, but older vehicles are also likely to be retired sooner; 2) each upgrading technique has its own strengths, weaknesses and variability/uncertainty. The emissions reductions due to retrofits are subject to many uncertain external factors, including environmental factors, fleet characteristics, and activity measures; and 3) during the period when equipment is being retrofitted and after installation, existing service levels (duty cycles) must be maintained, so NYSDOT’s public safety role for removing snow and ice and responding to emergencies is not compromised.