State of California

Summary of Board Meeting
February 24, 2000

Air Resources Board

Board Hearing Room, Lower Level
2020 "L" Street
Sacramento, California
MEMBERS PRESENT: Hons. Alan C. Lloyd, Ph.D., Chairman
    Joseph C. Calhoun, P.E.
    Doreen D'Adamo
    Mark DeSaulnier
    C. Hugh Friedman
    William F. Friedman, M.D.
    Matthew R. McKinnon
    Barbara Patrick
    Barbara Riordan
    Ron Roberts

00-1-2 Continuation of a Public Hearing to Consider the Adoption of a Public Transit Bus Fleet Rule and Emission Standards for New Urban Buses


The discussion on this proposed regulation was a continuation from the January 27, 2000, meeting. Although the public record was closed at the conclusion of the January meeting, the Board directed the staff to further analyze several outstanding issues and report back to the Board with recommendations in February.

The staff's original proposal presented at the January meeting contained two complementary elements designed to reduce emissions from urban transit buses: a multi-component transit bus fleet rule applicable to transit agencies, and more stringent emission standards for engines used in new urban buses, applicable to engine manufacturers.

The proposal was designed to encourage transit agencies to operate low-emission, alternative-fuel urban buses. However, to provide transit agencies with flexibility in determining their optimal fleet mix, the fleet rule would allow transit agencies to choose between two paths to reduce emissions - a diesel path and an alternative-fuel path. More stringent emission standards for oxides of nitrogen (NOx) and particulate matter (PM) would be implemented for model years 2004 through 2006 diesel and dual-fuel urban bus engines, and for all 2007 and subsequent model year urban bus engines.

The proposal would also reduce emissions from in-use urban buses. Transit agencies would be required to meet a NOx fleet average standard by October 2002 and perform retrofits to reduce PM emissions from 2003 and earlier model year diesel buses. To ensure effectiveness of retrofit and emission control aftertreatment devices, transit agencies using diesel fuel would be required to use low-sulfur diesel fuel beginning in July 2002.

To ensure long-term emission reductions, the proposal included a zero-emission bus (ZEB) component. Large transit agencies on the diesel path would be required to perform a ZEB demonstration project in 2003. By January 2006, the Board would be required to review the status of ZEB technology and the feasibility of implementing ZEB purchase requirements. Based on the outcome of the Board's feasibility review in 2006, ZEB purchase requirements would begin in 2008 for large transit agencies on the diesel path and in 2010 for large transit agencies on the alternative-fuel path.

At this meeting, the staff presented two recommendations that were revised subsequent to the January meeting. First, the staff recommended that the Board adopt an accelerated PM retrofit schedule for 2003 and earlier model year diesel buses. The accelerated retrofit schedule would provide significant PM reductions earlier than the staff's originally proposed retrofit schedule, and would reduce the public's exposure to toxic PM emissions.

The staff also recommended that the Board adopt a provision that would allow transit fleets to implement an alternative strategy to achieve emission reductions equivalent to those that would be achieved with the staff's originally proposed emission standards for model years 2004 through 2006 diesel and dual-fuel urban bus engines. Transit agencies that purchase diesel or dual-fuel urban buses could either purchase buses with engines meeting the 2004 through 2006 model year standards, or they could implement an alternative strategy for achieving emission reductions. As part of the alternative strategy, the Engine Manufacturers Association committed to produce urban bus engines meeting a 0.01 gram per brake horsepower-hour PM standard in October 2002 -- over a year ahead of when required -- and to implement a demonstration program of buses equipped with control technology designed to meet the staff's proposed 2004 standards. The staff included these components in its recommendation to the Board.

The proposed fleet rule and emission standards for new urban buses would reduce emissions of NOx and toxic diesel PM statewide. Additional emission reductions would occur from the voluntary operation of alternative-fuel buses in lieu of diesel buses.

The cost-effectiveness of the proposed new emission standards and the ZEB purchase requirements compares favorably with the cost-effectiveness of other mobile source and motor vehicle fuels regulations adopted by the ARB over the past decade.

The Board adopted the staff's proposal with the revised recommendations discussed above. However, the Board required that if a transit agency chooses to implement an alternative emission reduction strategy in lieu of purchasing lower-emitting model years 2004 through 2006 diesel or dual-fuel urban bus engines, the alternative strategy must achieve greater emission reductions, not just equivalent emission reductions. In addition, the Board also required that the Executive Officer shall bring the application of the first transit agency to apply for approval of an alternative emission reduction strategy to the Board for consideration. Finally, the Board directed the Executive Officer to develop a test procedure for the evaluation of hybrid electric bus emissions and to report back to the Board by mid-2001.


Approved Resolution 00-2 by a unanimous vote.


STAFF REPORT: Yes (102 pages)