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California ARB petitions US EPA for “Tier 5” stricter locomotive emissions standards

In an effort to accelerate the movement to zero- or near-zero emission locomotives, the California Air Resources Board (ARB) has petitioned the US EPA take action to adopt more stringent emission standards for locomotives. These new standards are to include standards for newly manufactured locomotives (which ARB refers to as “Tier 5”), and a new standard for Tier 4 locomotives upon remanufacture.

ARB is also requesting new remanufacturing standards equal to or more stringent than current Tier 4 emission levels for Tier 2 and 3 locomotive engines. ARB Chair Mary Nichols said the moves are needed to clean up the air in “high-risk” communities in and around the nation’s railyards.

The proposed emission standards would cut toxic and smog-causing emissions by 85% for diesel particulate matter (PM) and 66% for oxides of nitrogen (NOx) below current Tier 4 levels. Newly manufactured locomotives would have some zero-emission mile capability.


Top: Existing federal standards. Bottom: ARB’s proposed Tier 5 standard. Source: ARB. Click to enlarge.

ARB said that the proposed standards recognize advancements in technology that support zero-emission rail operation in impacted communities while also providing nationwide fuel savings for the railroads.

PM emissions for proposed Tier 5 compared to current Tier 4 (based on grams of PM per brake-horsepower-hour). Tier 4 line haul locomotives used for nationwide service typically range from 2,300 to more than 4,000 horsepower. Source: ARB. Click to enlarge.

EPA first established emission standards for hydrocarbons (HC), NOx, and PM for locomotives and locomotive engines in 1998, with revisions over time.

  • In 1998, EPA adopted Tier 0, Tier 1, and Tier 2 emission standards for original manufacture and for subsequent remanufactures of locomotives; these were applicable to locomotives with engine model years from 1973-2011.

  • In 2008, US EPA amended the 1998 locomotive regulation, establishing a Tier 3 and a Tier 4 emission standard, as well as stricter remanufacturing standards for remanufactured Tier 0-2 engines.

  • he new Tier 3 PM emission standards went into effect for engine model years 2012-2014 for line haul locomotives and represented a minor step change. The Tier 4 line haul locomotive standard, effective in 2015, requires a reduction of NOx and PM emissions of 90% for NOx and 95% for PM, relative to pre-Tier 0.

The key technologies used to achieve these reductions in NOx and PM emissions are exhaust gas recirculation and improvements to the cooling system. Tier 4 locomotives are commercially available and are now being phased in.

In the formal petition submitted for US EPA Rulemaking to reduce locomotive emissions, Nichols made it clear that recent studies have found that there are significant diesel exposure disparities by race and income among residents living in close proximity to most of the major railyards in California.

Nichols acknowledges that many steps have already been taken to clean up emissions from the nation’s complex freight delivery network. National locomotive emissions and diesel fuel standards, CARB agreements with railroads, California emission standards for drayage trucks and cargo equipment, and private and public investments in cleaner equipment are reducing overall emissions and health risk near our major railyards.

However, CARB believes that more can be accomplished, and that to deliver on the collective responsibility to improve conditions on the ground for overburdened communities, new action by US EPA to require a transition to zero and near-zero emission locomotives is necessary.



I'm loving this; The ARB is picking a fight with EPA and if you notice GHG is included on the request...this will force Trump and the Republicans to either admit to papering over the GHG problem openly or addressing the issue with something other than false political rhetoric. No one to date has proven that the affect of GHG isn't real.

The Lurking Jerk

The ARB is not picking a fight, they are simply making a request. What's more, they cite the most absurd reason possible for doing so-

"... recent studies have found that there are significant diesel exposure disparities by race and income among residents living in close proximity to most of the major railyards in California."

Meaning 'no fair, railyard diesel exposure isn't racially balanced'. Putting race into pollution exposure limits is as nutty as it gets, although yeah, its California.

Citing 'not proving a negative' (your last sentence) is equally absurd. There are some things that just aren't worth regulating to death. Regulating the lifeblood of the nation is one of them, if the strategy is to eventually regulate them out of existence. Not going after ocean-going ships is your first clue as to how irrational much of this regulation is. When the political left recognizes how difficult it has become to conduct business in this country, when they realize that a no-comprimise approach is unworkable, republicans, business, and providers will get on board with regulation. But not until then.


Trains could store LH2 and run SOFCs for longer range, higher efficiency and less pollution. We CAN take these actions we just DON'T.


I think out of this action,the EPA head will reject the idea because he's one of the fossil fuel industry's guy in Washington...put there with marching orders to maintain the status quo. His first moves have been to weaken the EPA by a reduction of the budget and programs, especially those having to do with the program that hurts the fossil fuel industry the most, that's GHG.


Lad pick your poison, we could all be driving motorcycles and trikes because they can get 73mpg in some circumstances. The upside, lower ghg, the downside is the more pollution, and everything else that comes with driving a motorcycle.

Energy isn't something to restrict to the highest bidder/ people who can afford it. (after taxing it into oblivion)

There was another article on here a while back of Ford and GM discussing CO2/mile generated by tesla, and how that would play into CAFE laws.

And as others point out, there are lower hanging fruit. Why go after something that is very efficient? Why not go after old homes, boats, and the older/failing vehicle population on the road. I am all for tail pipe tests. If people can't have a properly running cars... I believe a cash for clunkers round two would have various advantages to fix the average vehicle age/ poor operation by the owner.

I'd like some logic to the way government addresses problems.


Also, I'd be happy if the CARB/epa started probing everything new with an exhaust pipe for NOx, HC, and PM. Those three are a major health concern, and we need to address those before we block out the sun from space to deal with global warming. (my approach, as the sun has the single greatest affect on our global temperature, we could get fancy and make a big solar array in space, then laser down the power to a receiver)

Gasoline and mixed gasoline should make thier exit from most yard equipment as it's completely unregulated in most places, an hour of mowing your grass with a traditional mower is very harmful to those that breath.


Trucks larger than pickups use a lot of fuel and emit a lot of pollution. While we are at it look at pickups, more than one million per year sold and few do any work.


The Lurking Jerk: Is it wrong, though, that the racial distribution likely does expose minorities to more pollution?

Also, using the argument that minorities are exposed to more pollution is likely also a political tactic - if California can prove that there is a racial bias caused by locomotive emissions, the 14th Amendment actually requires them to enact this emissions standard, to equally protect them under the law.

Finally, California does go after oceangoing vessels, at least within the jurisdiction that they're able to do so:

CheeseEater88: Worth noting that California already does do emissions testing at least to some extent on everything with a tailpipe that's at least MY1998 (because MY1997 and older diesels, and MY1975 and older gassers are exempt). It's not everything, and it's not tailpipe tests at least on the OBD-II capable ones, but...

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