FRA Locomotive Emissions

Comparison Tool (LECT) 

User Guide
 

2 

LOCOMOTIVE EMISSIONS COMPARISON TOOL (LECT) USER GUIDE

The purpose of the Locomotive Emissions Comparison Tool (LECT) is to provide users with a 

standardized approach to estimating emission reductions from the implementation of FRA-funded 

projects, including locomotive replacement projects being considered for funding under the 

Consolidated Rail Infrastructure and Safety Improvements (CRISI) Grant Program and other discretionary 

grant programs. The LECT uses emission rates based on the U.S. Environmental Protection Agency’s 

Locomotive Engine Standards1

, as well as other data sources. The tool can provide users with estimates 

of emission reductions for projects that replace diesel engines with newer versions or with alternativefuel engines, including all-electric locomotives.

2

 

This document is organized into three sections—User Guide, Tool Methodology, and Examples—to aid 

the user in understanding and interpreting results from the LECT: 

• The User Guide provides directions for properly inputting values into the tool and definitions of 

both user inputs and tool outputs. 

• The Tool Methodology section outlines the steps taken by the tool to calculate emission 

reductions, as well as any associated assumptions. 

• The Examples section provides instructive scenarios that show how to use the tool in different 

types of project analysis.

Emission estimates from the LECT are not intended to meet specific requirements for State 

Implementation Plans (SIPs) or transportation conformity analyses. Information regarding the 

development of default emission rates and guidance on incorporating user-supplied emission rates can 

be found in the accompanying document, Locomotive Emissions Comparison Tool (LECT): Emissions Data

Documentation. 

1 U.S. Environmental Protection Agency, Emission Factors for Locomotives, EPA-420-F-09-025 (April 2009). 

Available at: https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100500B.TXT. 2 The most current version of the LECT is dated December 2023. 
 

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Locomotive Emissions Comparison Tool User Guide

Table of Contents

USER GUIDE................................................................................................................................................... 4

User Inputs................................................................................................................................................ 4

Tool Outputs ............................................................................................................................................. 6

Scenario Comparison (Optional)............................................................................................................... 7

Error Messages ......................................................................................................................................... 8

TOOL METHODOLOGY .................................................................................................................................. 9

Emission Rates Sources............................................................................................................................. 9

EXAMPLES ................................................................................................................................................... 10

Example 1: Switch Locomotive Replaced with Fuel Cell–Powered Model .............................................10

Example 2: Switch Locomotive Replaced with GenSet Model ............................................................... 12

Example 3: Large Line-Haul Locomotive Replaced with Diesel Tier 4 .................................................... 13

Example 4: Small Line-Haul Locomotive Replaced with Diesel Exceeding Tier 4 ...................................14

Appendix: Emissions Tables & Load Factors............................................................................................... 16
 

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USER GUIDE

This section describes each user input and tool output, as well as the emission reductions report, error 

messages, and other assumptions present in the tool. 

Note about Excel version and macros: to ensure proper tool operation, please use the desktop app 

version of Excel, not the online version. Also confirm that macros are enabled: File > Options > Trust 

Center > Macro Settings (check Enable VBA Macros)

User Inputs

User-defined inputs are described in Table 1. Inputs are specific to locomotive engine type and (for 

electric locomotives) project location. 

Table 1. User Inputs – Engine Repower or Replacement

Question User Input Units Description

(1) Project Year - Use the drop-down menu to select a year 

between 2019 and 2030. 

(2) Baseline equipment - Use the drop-down menu to select the baseline 

equipment associated with the project.

(3) Emissions tier of 

baseline equipment -

Use the drop-down menu to select the emissions 

standard to which the baseline equipment is held. 

Refer to Table A1 for help in determining the 

correct emissions tier.

(4) Engine type -

Use the drop-down menu to select the engine 

type associated with the repowered/replacement 

equipment.

(4a) eGrid Region* -

Use the drop-down menu to select the eGrid 

region associated with the location of the 

replacement electric equipment. If the project 

operates in multiple regions, consider using the 

“U.S.” national average (last item in drop-down).

4(b)

Manufacturersupplied emission 

rates

g/bhp-hr

Enter manufacturer-supplied certification data in 

the table. Note this input is only required for 

locomotives that exceed the Tier 4 diesel 

standards. 

(5)

Number of 

locomotives to be 

replaced

- Enter the total number of locomotives that will 

be repowered or replaced.
 

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Question User Input Units Description

(6)

Emissions tier of 

replacement 

equipment

-

Use the drop-down menu to select the emissions 

standard to which the repowered/replacement 

equipment will be held.

(7) Annual fuel use**

Gallons 

(per single 

locomotive)

Enter the annual fuel use for the baseline 

equipment and the replacement (if applicable) in 

gallons. Be sure to reflect any fuel efficiency

improvements for the replacement equipment.

(8) OPTIONAL – Save and 

Compare Scenarios -

Use the buttons to Save, Compare, or Delete 

Existing Scenario(s). See below for further details

on how to use this feature. 

* For all-electric or equivalent replacement only.

** Please refer to the Fuel Use section below when estimating the annual fuel use for replacement 

equipment.

Baseline Equipment: Users may select two different types of equipment: Class II/III line-haul locomotive 

or switch locomotive.

Emissions Tier: Users may select the emissions tier that corresponds to the EPA emissions standard to 

which their equipment is held. If the emissions tier is unknown, the appendix provides guidance to help 

identify the appropriate tier. Table 2 below identifies how to select an appropriate tier from the 

appendix table given the type and condition of the baseline equipment. For locomotive technologies 

that exceed the current, highest tier for diesel locomotives (Tier 4), users should input emissions 

certification data from the manufacturer. 

Table 2. Appendix Table Section Given Baseline Equipment

Baseline Equipment Condition of Baseline Equipment Appendix Table Section

Locomotive

(line-haul or switch)

Not remanufactured or 

remanufactured pre-2008

use tiers without ‘+’ symbol

Locomotive

(line-haul)

Remanufactured in 2008+ and original 

year of manufacture was pre-2012

if Tier 0-2, use tier with ‘+’ symbol*

Locomotive

(switch)

Remanufactured in 2008+ and original 

year of manufacture was pre-2011

if Tier 0-2, use tier with ‘+’ symbol*

*EPA holds remanufactured locomotives to a higher emissions standard.

Engine Type: Users may select one of five different engine types for the replacement equipment: diesel, 

diesel GenSet, all electric, battery or equivalent (e.g., batteries, hydrogen fuel cells, or grid power via 

overhead catenary lines), diesel-battery hybrid, or other technology. 

Note that the diesel GenSet option in the tool is currently only available for switch locomotives. Diesel 

GenSets are a multi-engine configuration (typically 2 to 3 engines) that operate in series, with each 
 

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engine powering up as the load increases. The tool assumes that GenSets meet the EPA Tier 4 standards 

for switch locomotives. See the Emissions Data Documentation for further information. 

Number of Locomotives: Users may input any value greater than 0 that corresponds to the total 

number of pieces of equipment being replaced. The tool assumes that all equipment included in each 

scenario run has the same characteristics (e.g., engine type, tier). If users wish to calculate emission 

reductions for more than one locomotive type, they should run the tool multiple times and sum the 

benefits from all scenarios to calculate total emission reductions for the entire fleet. See the Scenario 

Comparison section for details about how to save scenario and sum benefits. 

Fuel Use: Users can input the annual diesel fuel use (in gallons) by a single locomotive or estimated 

annual diesel or diesel-equivalent fuel use for replacement equipment. For electric replacement 

locomotives, annual fuel use is zero. Newer locomotive engines may have lower fuel consumption. 

Expected fuel efficiency improvements differ depending on the engine type: 

Diesel: Many technologies for reducing NOX emissions cause decreases in the fuel efficiency of 

the engine. Without additional treatments, the fuel efficiency of diesel Tier 1 locomotives is 

between 5 and 15 percent less than that of Tier 0 engines.

3 The EPA recognized a short-term 

trend of decreasing fuel efficiency as a result of implementing the older 1998 Locomotive 

Emission Standards; however, fuel efficiency was expected to remain constant or increase due

to continual improvements in locomotive fuel economy in the long-term.4 Industry experts have 

estimated that diesel Tier 3 engines will show a 5 percent increase in fuel efficiency compared 

with Tier 2, and that Tier 4 engines will perform similarly.5

 

GenSet: For diesel GenSet switch locomotives, in the absence of specific fuel consumption data, 

users may assume a 25 percent reduction in fuel use compared with traditional diesel switchers.

Please see the Emissions Data Documentation for additional information on GenSets.

Diesel-Battery Hybrid: Hybrid locomotives use a diesel engine in conjunction with a battery pack. 

Users should reflect anticipated fuel savings associated with the project. Please see the 

Emissions Data Documentation for further information about hybrid locomotive operational and 

charging modes and associated fuel savings. 

Tool Outputs

Emission benefits are derived when replacing diesel locomotive engines with newer or cleaner-fuel 

versions. In the tool output, a positive change in emissions is equivalent to an emissions reduction 

3 Argonne National Laboratory, Railroad and Locomotive Technology Roadmap (December 2002). Available at:

https://publications.anl.gov/anlpubs/2003/02/45512.pdf.

Note that fleetwide averages for 2002 to 2009 are lower than the per-locomotive estimates, although the share of 

the fleet by each emission tier is not known. Some emissions reduction technologies, such as exhaust-gas 

recirculation (EGR), can further decrease fuel efficiency. 

4 U.S. Environmental Protection Agency, Retrospective Study of the Cost of EPA Regulations: A Report of Four Case 

Studies (August 2014). Available at: https://www.epa.gov/sites/default/files/2017-09/documents/ee-0575_0.pdf. 5 California Air Resources Board (CARB), Technology Assessment: Freight Locomotives (November 2016). Available 

at: https://ww2.arb.ca.gov/sites/default/files/classic/msprog/tech/techreport/

final_rail_tech_assessment_11282016.pdf. 
 

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(benefit), while a negative value can be interpreted as an emissions increase (disbenefit). Emission 

reductions (i.e., benefits) are calculated for five air pollutants—CO, NOX, PM2.5, PM10, and VOC—

reported in short tons per year, and three greenhouse gases (GHGs)—CO2, CH4, and N2O—reported in 

metric tons per year. CO2e is calculated based on the global warming potentials (GWP) of CO2, CH4, and 

N2O, and provides an indication of the total impact of GHG emissions on global climate.6

 

Upstream GHG emissions are reported for baseline and replacement equipment in metric tons. Energy 

consumption (in kWh) is also provided for both upstream processes (i.e., energy to produce, transport, 

and store diesel, and energy usage for electricity production) and for locomotive operation. See below 

and the accompanying Emissions Data Documentation for details.

Note that users will need to click “Calculate or Update Results” again if any changes are made to the 

inputs after running the tool.7 The tool will not update the reported emission reductions automatically.

Export Results to PDF: Click this button to export results, including scenario comparisons (see below) to 

a PDF. The PDF will include user-supplied inputs and emission reductions. 

Scenario Comparison (Optional)

The LECT includes a “Compare Scenarios” feature that allows users to compare and sum emissions 

benefits across different locomotive replacement scenarios. This feature is optional, and the tool will 

calculate results without saving each scenario run. The section below describes the Compare Scenario 

inputs and outputs: 

Engine Repower or Replacement Tab

“Yes, Save Scenario”: click this button to save the current scenario. You will be prompted to enter a 

scenario name. You may save up to 10 scenarios. 

“Compare Scenarios”: click this button to navigate to the Compare Scenarios tab where you can view 

emissions reduction results for all saved scenarios.

“Delete an Existing Scenario”: click this button to delete an existing scenario from the Compare 

Scenarios tab. 

Compare Scenarios Tab

Features on this tab allow users to compare emissions benefits between scenarios (e.g., upgrading to a 

Tier 4 diesel vs. battery-electric locomotive) and sum emissions benefits across multiple locomotive 

replacement projects. As with the main tool interface described above, emission reductions are shown 

for all air pollutants and greenhouse gases.

6 GWP is a measure of how much energy the emissions of 1 ton of a gas will absorb over a given period of time, 

relative to the emissions of 1 ton of carbon dioxide (CO2). See the EPA’s Understanding Global Warming Potentials

(web page) (April 18, 2023): https://www.epa.gov/ghgemissions/understanding-global-warming-potentials. 7 The tool does not automatically store user information, inputs, or outputs unless the user chooses to save 

scenarios.
 

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In the Scenario Name column, use the drop-downs to switch between scenarios. Select whether to sum 

results across all selected scenarios. Click the “Export results to PDF” button to create a PDF of the 

scenario comparison results. 

Error Messages

Error messages that users may encounter in this tool, the reason for the error messages, and the 

solutions are listed in Table 3.

Table 3. Error Messages

Error Message Reason for Error Solution

ERROR: Missing Project Year. No input provided for Project 

Year.

Select a Project Year from the

drop-down menu.

ERROR: No baseline equipment 

selected.

No input provided for 

baseline equipment type.

Select an equipment type 

from the pull-down menu.

ERROR: Missing emissions tier for 

[baseline or replacement] 

equipment.

No input provided for 

emissions tier.

Select an emissions tier from 

the pull-down menu. Refer to 

Table A1 for help determining 

an appropriate tier.

ERROR: Missing locomotive's eGrid 

region for upstream electricity 

emission calculations.

No input provided for 

equipment operations region

Select an eGrid region from 

the pull-down menu. Refer to

Figure A2 for help determining 

the appropriate region.

ERROR: Missing number of 

locomotives to be replaced.

No input provided for the 

number of locomotives.

Input a whole number greater 

than 0.

ERROR: Missing engine type of the 

replacement equipment.

No input provided for the 

engine type of the 

replacement equipment.

Select an engine type from the 

pull-down menu.

ERROR: The Diesel GenSet option in 

this tool is currently only available 

for switch locomotives.

The diesel GenSet engine is 

not available for the 

equipment type selected.

Change the baseline 

equipment to “Switch 

Locomotive.”

ERROR: Missing annual fuel use for 

one locomotive.

No input provided for 

locomotive activity.

Input a number greater than 0 

gal/yr.

ERROR: Name for the scenario 

cannot be blank.

The name entry was blank in 

the pop-up window after 

pressing the “Yes, Save 

Scenario” button or the 

“Delete an Existing Scenario” 

button. 

Enter a non-empty name for 

the scenario when saving or 

deleting.
 

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Error Message Reason for Error Solution

ERROR: The scenario name already 

exists. Please try again and enter a 

unique name. 

This name already exists in 

the list of saved scenarios. 

Enter a unique name instead 

of using a name that already 

exists as a saved scenario. 

WARNING: No scenarios to delete

There are no saved scenarios 

so the “Delete an Existing 

Scenario” and “Clear All 

Scenarios” button won’t 

work.

Save a scenario for 

comparison before trying to 

delete a single scenario or 

clearing all scenarios.

ERROR: Missing emission factors for 

replacement equipment.

The emission rates table 

(manufacturer-supplied data) 

is blank or incomplete.

For locomotives that exceed 

Tier 4 standards, input 

emission rates in g/bhp-hr.

Click “Calculate or Update Results” to recalculate the results once errors are resolved.

TOOL METHODOLOGY

Emission reductions in the LECT are based on the comparison of emissions from the baseline and 

replacement equipment. The tool assumes all baseline equipment operates with diesel fuel. Users have 

the option to power their replacement locomotives with diesel or an alternative fuel, including liquefied 

natural gas and electricity. 

Emission Rates Sources

Emission rates for locomotive applications can be found in Table A1 of the appendix as well as the 

Emissions Data document that accompanies this User Guide. 

Diesel: Diesel engine emission rates for locomotive operation are based on EPA emission 

factors.8 Replacement equipment emissions are based on newer engines meeting the more 

stringent EPA standards. If the CRISI project involves engine technologies that exceed Tier 4 

standards, users should provide manufacturer-supplied emissions certification data. Upstream 

emissions from diesel production, transport, and storage are also provided in the tool. Emissions 

are based on well-to-use emissions from the Department of Energy Argonne National Lab’s 

GREET model.9

All-electric, battery or equivalent: Operational emission rates for electric locomotives or the 

equivalent (e.g., battery- or hydrogen-fuel-cell-powered locomotives) are zero for all air 

pollutants and GHGs; however, the tool outputs upstream GHG emissions estimates for electric 

locomotives based on EPA’s eGRID data. eGRID provides emission rates (lb/MWh) for electricity 

generation based on the source mix of electricity generation by region. Please refer to Table A2 

8 U.S. Environmental Protection Agency, Emission Factors for Locomotives, EPA-420-F-09-025 (April 2009). 

Available at: https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100500B.TXT. 9 Argonne National Laboratory. The Greenhouse gases, Regulated Emissions, and Energy use in Technologies 

Model (GREET) Tool (2022). Available at: https://greet.anl.gov/net.
 

10

and Figure A2 in the appendix for information on eGRID regions. To calculate upstream 

emissions, the tool assumes a diesel fuel-to-electricity ratio of 64.5 gallons per MWh for linehaul locomotives and 73.7 gallons per MWh for switcher locomotives (i.e., a replacement 

electric switcher will use 1 MWh of electricity for every 73.7 gallons of fuel consumed by the 

original diesel equipment).10 

Additional information on the emission rates and tool calculations can be found in the Emissions Data 

documentation. The “Upstream” tab in the tool includes the underlying emission rates for upstream 

electricity generation and diesel fuel production, transport, and storage. 

EXAMPLES

The three examples below highlight how the tool calculates emissions savings by applying user-provided 

operational data for completely replacing a locomotive. While users will likely have specific operational 

data available, these typical activity values may provide a helpful reference:

• Average annual fuel consumption for line-haul locomotive = 130,000 gallons diesel

• Average annual fuel consumption for switch locomotive = 30,000 gallons diesel

Example 1: Switch Locomotive Replaced with Fuel Cell–Powered Model

A state has implemented stricter air pollution regulations. To comply with the new rules, a rail yard 

decided to replace their three 1980s-era switch locomotives (that have not been remanufactured post 

2007) with a new hydrogen fuel cell model11 that has no regulated emissions (only water vapor). The rail 

yard currently consumes 100,000 gallons of diesel fuel annually across the three switchers. The project 

will be implemented in 2023. 

In the Engine Replacement module, the user would select the following inputs:

Question 1: Project Year: 2023

Question 2: Baseline Equipment: Switch Locomotive

Question 3: Emission tier of baseline equipment: Tier 0 

If the emissions tier of the baseline equipment is unknown, the user could refer to Table A1– Locomotive 

Emission Standards in the Appendix of this document. Switch locomotives built in the 1980s that have 

not been remanufactured post 2007 fall under the Tier 0 EPA standards.

10 California Air Resources Board. Appendix F: Technology Feasibility Assessment for the Proposed In-Use 

Locomotive Regulation. Available at: 

https://ww2.arb.ca.gov/sites/default/files/barcu/regact/2022/locomotive22/appf.pdf (see Table 8). Accessed 

December 2023.

11 K. Hess et al. (Fuelcell Propulsion Institute), “Demonstration of a Hydrogen Fuel-Cell Locomotive” (2010). 

Available at: https://pdfs.semanticscholar.org/bc5b/8df3251a993d608295aad4ae795678c046cf.pdf.
 

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Question 4: Engine type of repowered/replacement equipment: All-Electric, Battery or 

Equivalent

Since hydrogen fuel cells do not generate regulated emissions (only water vapor), the user can select the 

“All-Electric, Battery or Equivalent” option for this question as the fuel cell is equivalent to all-electric.

Since an Electric or Equivalent engine has been selected for the replacement, a project region (eGRID) 

has to be selected. Additionally, once the “All-Electric, Battery or Equivalent” option is selected, the 

Question 6 input cell will be grayed out.

Question 4a: Region project is located in: RFCE

If the project location is unknown, the user can enter the region as “U.S.” for a more general estimate. 

The different regions across the United States are in Figure A1 of the Appendix.

Question 5: Number of Locomotives to be replaced: 3

Question 6: Emission tier of repowered/replacement equipment: (leave grayed out)

Since the replacement locomotive is not powered by diesel fuel and therefore not held to EPA’s 

diesel locomotive tiers, the user should leave this question blank. If a value is input for Question 6

by mistake, the tool will still run correctly.

Question 7: Input annual fuel use in gallons of diesel: 33,333

Note: The input activity is for one locomotive, not the entire rail yard operation. 100,000 gallons of diesel 

divided by 3 locomotives gives an annual average of 33,333 gallons per switcher.

Once the inputs are entered, click the “Calculate or Update Results” button to estimate emission 

reductions for the project. The estimated operational emission reductions are:
 

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Example 2: Switch Locomotive Replaced with GenSet Model

A county is working with a busy railyard to replace old diesel switchers with GenSet models to save fuel 

and reduce local emissions impacts on neighboring communities. Each switch locomotive uses 

approximately 30,000 gallons of fuel annually and pre-dates the EPA’s first locomotive emissions 

standards (uncontrolled). 

In the tool, the user would select the following inputs:

Question 1: Project Year: 2026

Question 2: Baseline Equipment: Switch Locomotive

Question 3: Emission tier of baseline equipment: Uncontrolled

Question 4: Engine type of repowered/replacement equipment: Diesel GenSet

Question 5: Number of Locomotives to be replaced: 4

Question 6: Emission tier of repowered/replacement equipment: Tier 4

Question 7: Input annual fuel use for baseline equipment in gallons of diesel: 30,000

Question 7(a): Input annual fuel use for replacement equipment in gallons of diesel: 22,50012

Once the inputs are entered, click the “Calculate or Update Results” button to estimate emission 

reductions for the project. The estimated operational emission reductions are:

12 Assuming 25% fuel savings for the replacement GenSet model (30,000 * 0.75)
 

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Example 3: Large Line-Haul Locomotive Replaced with Diesel Tier 4

A state is working with a Class II railroad to replace one of its oldest diesel locomotives with a newer 

engine that meets Tier 4 emissions standards. The current engine meets Tier 1 standards and uses 

approximately 130,000 gallons of fuel each year. Fuel efficiency savings of 10 percent are expected with 

the newer engine. 

In the tool, the user would select the following inputs:

Question 1: Project Year: 2024

Question 2: Baseline Equipment: Line-Haul Locomotive (Class II/III)

Question 3: Emission tier of baseline equipment: Tier 1

Question 4: Engine type of repowered/replacement equipment: Diesel 

Question 5: Number of Locomotives to be replaced: 1

Question 6: Emission tier of repowered/replacement equipment: Tier 4

Question 7: Input annual fuel use for baseline equipment in gallons of diesel: 130,000

Question 7(a): Input annual fuel use for replacement equipment in gallons of diesel: 117,000

Once the inputs are entered, click the “Calculate or Update Results” button to estimate emission 

reductions for the project. The estimated emission reductions are:
 

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Example 4: Small Line-Haul Locomotive Replaced with Diesel Exceeding Tier 4 

A state is working with a Class II railroad to replace one of its oldest diesel locomotives with newer 

engines that exceed Tier 4 emissions standards and have manufacturer-supplied emission factors data. 

The current engines meet Tier 1 standards and each use approximately 130,000 gallons of fuel each 

year. Fuel efficiency savings of 10 percent are expected with the newer engines. 

In the tool, the user would select the following inputs:

Question 1: Project Year: 2026

Question 2: Baseline Equipment: Line-Haul Locomotive (Class II/Class III)

Question 3: Emission tier of baseline equipment: Tier 1

Question 4: Engine type of repowered/replacement equipment: Diesel 

Question 5: Number of Locomotives to be replaced: 2

Question 6: Emission tier of repowered/replacement equipment: Exceeds Tier 4

Question 6(a): Manufacturer-provided emission factors data:

NOX: 0.85

PM10: 0.01

PM2.5: 0.025

HC: 1.28

CO: 0.01

Question 7: Input annual fuel use for baseline equipment in gallons of diesel: 130,000

Question 7(a): Input annual fuel use for replacement equipment in gallons of diesel: 117,000

Once the inputs are entered, click the “Calculate or Update Results” button to estimate emission 

reductions for the project. The estimated emission reductions are:
 

15
 

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Appendix: Emissions Tables & Load Factors

Table A1. Locomotive Emission Factors13

 Emission Factors (g/bhp-hr)

Fuel Type Year of Manufacture Tier14 NOX PM HC15 CO

Diesel (Line-haul)

Pre-1973 Uncontrolled 13.00 0.32 0.48 1.28

1973-1992 Tier 0 8.60 0.32 0.48 1.28

1973-1992 Tier 0+ 7.20 0.20 0.30 1.28

1993-2004 Tier 1 6.70 0.32 0.47 1.28

1993-2004 Tier 1+ 6.70 0.20 0.29 1.28

2005-2011 Tier 2 4.95 0.18 0.26 1.28

2005-2011 Tier 2+ 4.95 0.08 0.13 1.28

2012-2014 Tier 3 4.95 0.08 0.13 1.28

2015+ Tier 4 1.00 0.015 0.04 1.28

Diesel (Switch)

Pre-1973 Uncontrolled 17.40 0.44 1.01 1.83

1973-2001 Tier 0 12.60 0.44 1.01 1.83

1973-2001 Tier 0+ 10.60 0.23 0.57 1.83

2002-2004 Tier 1 9.90 0.43 1.01 1.83

2002-2004 Tier 1+ 9.90 0.23 0.57 1.83

2005-2010 Tier 2 7.30 0.19 0.51 1.83

2005-2010 Tier 2+ 7.30 0.11 0.26 1.83

2011-2014 Tier 3 4.50 0.08 0.26 1.83

2015+ Tier 4 1.00 0.015 0.08 1.83

GenSet* 2015+ Tier 4 1.00 0.015 0.08 1.83

Electric

(or equivalent)◊ All N/A 0.0 0.0 0.0 0.0

Tiers with “+” are applicable only to locomotives that were originally manufactured in the 

corresponding Year of Manufacture range and remanufactured in 2008 or later; EPA holds these 

remanufactured locomotives to a higher emissions standard.

*Emission rates are estimated at the Tier 4 switch locomotive emission rates (refer to Emissions Data 

Documentation for details). ◊

Operational emissions only. See Figure A2 and Table A2 for emission rates used to quantify 

emissions from upstream electricity generation. 

13 U.S. Environmental Protection Agency, Emission Factors for Locomotives, EPA-420-F-09-025 (April 2009). 

Available at https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100500B.TXT. 14 The EPA tiers may also be applied to diesel-battery hybrids (diesel engine emissions) and other technologies and 

fuels, such as biodiesel. These locomotives should be certified to meet or exceed Tier 3/4 standards. 15 Hydrocarbon (HC) emission factors were converted to volatile organic compounds (VOC) emission factors using 

conversion factors developed by EPA. Please see the Emissions Data Documentation for further detail. 
 

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Table A2. eGRID Subregion Total Output Emission Rates (lb/MWh)16

16 U.S. Environmental Protection Agency, Summary Data eGRID with 2021 Data (web page) (January 30, 2023). 

Available at https://www.epa.gov/egrid/summary-data.

eGRID 

Subregion CO2 CH4 N2O CO2e 

AKGD 1067.7 0.091 0.012 1073.7

AKMS 485.2 0.025 0.004 487.1

AZNM 819.7 0.052 0.007 823.1

CAMX 531.7 0.031 0.004 533.6

ERCT 813.6 0.054 0.008 817.2

FRCC 832.9 0.053 0.007 836.3

HIMS 1134.4 0.135 0.021 1143.9

HIOA 1633.1 0.176 0.027 1645.5

MROE 1582.1 0.148 0.022 1592.3

MROW 995.8 0.107 0.015 1003.1

NEWE 539.4 0.072 0.009 544

NWPP 634.6 0.058 0.008 638.5

NYCW 816.8 0.019 0.002 817.9

NYLI 1210.9 0.126 0.016 1218.9

NYUP 233.1 0.015 0.002 234

PRMS 1558 0.081 0.013 1563.9

RFCE 672.8 0.049 0.007 676

RFCM 1214.1 0.115 0.016 1221.8

RFCW 1046.1 0.095 0.014 1052.5

RMPA 1158.9 0.109 0.016 1166.2

SPNO 991.7 0.108 0.016 999.1

SPSO 1031.6 0.08 0.012 1037

SRMV 772.7 0.04 0.006 775.4

SRMW 1543 0.171 0.025 1554.7

SRSO 891.9 0.067 0.01 896.4

SRTV 931.6 0.087 0.013 937.5

SRVC 639.7 0.052 0.007 642.9

U.S. 852.3 0.071 0.01 857
 

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Figure A1. eGrid Regions17

17 U.S. Environmental Protection Agency, eGrid Data Explorer 2021 (web page) (September 26, 2023). Available at:

https://www.epa.gov/egrid/data-explorer.