ARB Approves Revisions to Urban Bus Retrofit Rule

On October 24, 2002, ARB adopted revisions to the urban bus rule. The modifications will provide greater incentive for retrofitting 1994 and later model year buses sooner than would have been the case under the existing requirements. The revised rule establishes fleet-wide emission limits and allows individual transit companies to pursue a strategy, including retrofits and early retirement, that is best suited for their fleet of buses. The transit authority must reduce PM emissions by a growing percentage from a January 1, 2002 baseline or meet a 0.1 g/bhp-hr PM fleet average. Table 1 below sets out the required percentage reduction requirements.

Table 1.
Fleet-Wide Average Percentage PM Reduction Requirement
from 2002 Baseline

Year (as of January 1)	Diesel Path	CNG Path
2004	40%	20%
2005	60%	40%
2006	60%	40%
2007	85%	60%
2008	85%	60%
2009	85%	85%

The revised rules also give transit authorities in the SCAQMD until January 31, 2004 to elect to change from the diesel path to the alternative fuel path and allows transit companies on the diesel path to purchase alternative-fueled buses with NOx emissions greater than 0.5 g/bhp-hr between 2004 and 2006.

For more information, ARB’s Nancy Steele at (626) 350-6598 or nsteele@arb.ca.gov.