Compliance won't come cheap: what EPA's Tier 3 and Tier 4 locomotive emissions standards mean for manufacturers and railroads

Railway Age, Sept, 2008 by David E. Brann

When the U.S. Environmental Protection Agency published its first set of locomotive emissions regulations in 1998, manufacturers and railroads believed that by the time the industry was well on its way toward compliance, EPA would be working on additional standards. Sure enough, in 2003, EPA began development of a new locomotive rule, finalized this spring: 40 CFR Part 1033, which took effect on July 7, 2008.

CFR Part 92, the original rule, set Tier 0 standards for locomotives originally manufactured between 1973 and 2001 when overhauled in 2002 or later, and for some new units manufactured in 2000 and 2001; Tier 1 standards for new locomotives manufactured in 2002 through 2004; and Tier 2 standards for new locomotives manufactured in 2005 and later. Part 1033 adds Tier 3 and Tier 4, affecting new locomotives manufactured in 2012 and 2015, respectively, and tightens the standards affecting locomotives previously regulated by Part 92.

Both rules require most locomotives to meet standards on a long-haul line-haul cycle that emphasizes high load operation, and a switch cycle that emphasizes idle and low load operation, and is intended to represent switching operations and the emissions of line-haul locomotives in yards and congested areas. For simplicity, only the line-haul standards are discussed here, except when specifically treating switching locomotives.

Major emissions from locomotive diesel engines are nitrogen oxides (NOx) and particulate matter (PM). Carbon dioxide (CO) and unburned hydrocarbons (HC) are also regulated, but locomotives are not major sources of them. Exhaust smoke is also regulated. The Tier 0 and Tier 1 standards were intended to reduce NOx emissions by 33% and 50%, respectively, while preventing increases in other emissions, particularly PM, which tends to increase as NOx is reduced. Tier 2 standards reduced NOx by 67% from pre-control levels, and cut PM in half.

After publication of Part 92, EPA developed rules governing emissions from on-highway trucks and nonroad machinery that included very low NOx and PM standards and forced aftertreatment measures to further clean the exhaust. In 2003 discussions with manufacturers and in an Advanced Notice of Proposed Rulemaking published in 2004, EPA announced its intention to extend such standards to locomotives and marine vessels, starting as early as 2011. The industry responded that 2011 was too early. The rule was ultimately resolved to include two new tiers for new locomotives, as well as emissions reductions for locomotives manufactured in 1973 or later. Figure 1 (above) shows the new locomotive NOx and PM standards, and includes Tier 0, 1, and 2 standards of Part 92 for comparison. Tier 3, effective for locomotives manufactured in 2012, maintains Tier 2 NOx levels while again halving PM emissions. Tier 4, effective in 2015, is intended to force aftertreatment for compliance. It requires a 90% reduction in NOx and a 93% reduction in PM from uncontrolled levels.

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Figure 2 (p. 50) shows required emissions reductions from existing locomotives. Part 1033 standards, often referred to as Tier 0 , Tier 1 , and Tier 2 , emphasize reduction of PM. PM from Tier 0 and Tier 1 locomotives is cut almost to Tier 2 levels, while PM from Tier 2 locomotives is cut to Tier 3.

As in Part 92, the standards for existing locomotives are applicable to individual units when they are overhauled. Tier 0 and Tier 1 standards are effective with 2010 overhauls, and Tier 2 standards are effective with 2013 overhauls. But in all cases they are effective as early as 2008, if an EPA-certified retrofit kit meeting the standards is available at the time of overhaul. The railroads' obligation to apply certified retrofit kits is limited to 50% of total overhauls in 2008 and 70% in 2009.

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A new requirement is that all locomotives complying with Part 1033 be equipped with idle reduction devices, either when delivered from the factory or before they are placed back into service after an overhaul. The engine must be shut down after a maximum 30 minutes of idle, and can be restarted only to protect the engine, to keep batteries charged or compressed air supplies up, or to accommodate crew comfort or safety.

Tier 3 standards for new locomotives, as well as the Tier 0 , Tier 1 , and Tier 2 standards for existing units, are likely to be met by engine modifications and adjustments like those used to meet earlier standards. EPA was careful not to set standards for older locomotives that would require non-cost-effective modifications. For instance, compliance does not require addition of separate circuit charge air cooling to older locomotives not originally equipped.

In Part 92, EPA recognized that lighter duty cycles resulted in higher emissions than heavy duty line-haul cycles for the same engine, and set the switch cycle standards higher than the line-haul standards. In Part 1033, EPA has noted the emissions improvements afforded by various repower solutions for switch locomotives (see illustrations on pp. 52-56), and chose to set lower Tier 3 and Tier 4 switch cycle standards. The standards of Parts 92 and 1033 are shown graphically in Figure 3 (p. 50). Tier 3 and Tier 4 switch cycle standards are numerically equal to or lower than line-haul standards.