Friday, October 23, 2020

In-Use Locomotive Regulation Concepts




In 1998 and 2005, California Air Resources Board (CARB) entered into enforceable agreements with the two major freight railroads operating in California, Union Pacific and BNSF, ensuring an improved average emission standard for fleets (Tier 2), and wide adoption of idle-limiting devices on most locomotives.  Although the agreements ensured faster adoption of cleaner technologies than otherwise would have occurred at the time, additional emissions reductions are critical to address locomotives’ continued health impacts on communities. 



Figure 1: Higher Tiers emit fewer pollutants, yet railroads are increasing use of Tier 2+ locomotives and purchasing fewer, if any, Tier 4 locomotives.

Though moving cargo by trains produced fewer emissions than trucks in the past, by 2023 trucks will become the lower emission technology in California unless railroads replace older locomotives with the cleanest commercially available locomotives (currently Tier 4) or better.  California’s truck regulations will require trucks to transition to full zero-emission, yet locomotives lack necessary federal regulation of their engines that could reduce their pollutant emissions.  See CARB’s draft Truck vs. Train analysis for more information.   


CARB has heard the community’s desire for minimizing the health impacts that rail activities have on their residents.  The Governor also recently highlighted the importance of transitioning to zero-emission transportation technology in his Executive Order N-79-20, which calls for 100 percent of off-road vehicles and equipment operations to be zero-emission by 2035.  CARB is working with industry to create and test zero-emission locomotive technologies. As discussed in CARB’s draft Mobile Source Strategy, such technologies are critical to the State’s ability to protect public health, address climate change, and meet both State and federal air quality standards.


As illustrated in the graphic below, all railyard equipment under State control is transitioning to zero-emission, while locomotive engines – which are regulated by the federal government – are not.  In the absence of federal action to address harmful emissions from locomotives, CARB is developing regulatory concepts to reduce criteria pollutants, toxic air contaminants, and greenhouse gas emissions for locomotives in-use. These concepts are intended to be implemented statewide and provide an opportunity for the railroads to better address regional pollution and   long-standing environmental justice concerns with communities near railyards.  The goal of the new regulatory concepts is to accelerate immediate adoption of advanced cleaner technologies for all in-use locomotive operations. 



Figure 2: Non-locomotive equipment and vehicles that operate at railyards are quickly transitioning towards zero-emission technology. CARB’s in-use locomotive regulation would help reduce emissions and encourage zero-emission technologies for locomotives to be further developed.

CARB staff are looking for ways to update the proposed regulatory concepts to incorporate zero-emission technology, and will host public presentations on October 29 and 30 to provide more information about the state-of-technology and regulatory concepts (see meeting details below).

Summary of Regulatory Concepts

CARB proposes to address the health effects from in-use locomotive emissions with the following three regulatory concepts:


1)   The Locomotive Emission Reduction Spending Account: This would require locomotive operators to mitigate PM emissions by paying into an account.  Dirtier locomotives would require higher mitigation in the form of higher payment to the account.  Funds in the account must be used by the operators to purchase new Tier 4 or cleaner locomotives. 


2)   The Useful Life Limit on In-Use California Locomotives:  Currently, there is no limit on how many years a locomotive can operate in California. Locomotive owners can remanufacture their locomotive to its originally built emissions standards as many times as they want.  This allows the locomotive to continue producing emissions based on an emissions standard that may be twenty years or more out-of-date. The proposed useful life limit would cap the years a locomotive can operate in California, based on the definition of its useful life.  It would allow the locomotive to be used for two useful lives (currently calculated to be 23 years), and then the locomotive would be banned from operating in the state, unless it meets the cleanest emissions standard (currently Tier 4) or cleaner. 


3)   The Limit on Unnecessary Locomotive Idling: Communities have reported that some locomotives are idling in excess of 30 minutes. Although locomotives are permitted to idle for more than 30 minutes under certain circumstances by Federal law, communities are concerned that these locomotives are idling outside of those special circumstances.  Idling often occurs inside railyards, and the emission burden of several idling locomotives within a railyard is especially harmful to disadvantaged community members living near the railyards.  In order to minimize emissions from excessive idling, CARB would create an in-use requirement that incorporates a 30-minute idling limit similar to the Federal requirements, enforceable by CARB staff or an air district through an MOU.

To implement these concepts, the proposed regulation would also require locomotive operators to report locomotive usage, idling, and maintenance information.   

Public Comment and Next Steps

CARB staff will host public online discussions, to further develop these concepts, on October 29 and October 30, 2020. 


Visit our Meetings & Workshops webpage for up-to-date information and public presentation materials.



We encourage you to share your stories about your community’s experiences with locomotives.  Comments, pdf-based photos, and links to videos can be posted on the informal comment docket.  The informal comment docket will close on November 13 at 12:00 PM. You can continue to comment through the formal regulatory process and by emailing after the docket closes.

Visit our Meetings & Workshops webpage for up-to-date information and public presentation materials.


Comments, pdf-based photos, and links to videos can be posted on the informal comment docket or sent to


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