1 

Locomotive Emission Inventories for the United States from ERTAC Rail 

Michelle S. Bergin 

GA Environmental Protection Division 

Air Protection Branch, Planning and Support 

4244 International Pkwy, Suite 136, Atlanta, GA 30354 

michelle.bergin@dnr.state.ga.us 

Matthew Harrell 

Illinois Environmental Protection Agency 

Air Quality Planning Section 

1021 North Grand Avenue East, Springfield, IL 62794-9276 

matthew.harrell@Illinois.gov 

Mark Janssen 

Lake Michigan Air Directors Consortium (LADCO) 

9501 W Devon Ave, Suite 701, Rosemont, IL 60302 

janssen@ladco.org 

ABSTRACT 

Three nationwide locomotive emission inventories have been developed in collaboration with 

twenty-seven state air protection agencies, coordinated through the Eastern Regional Technical 

Advisory Committee, with support from railroads and industry associations. The inventories are for 

Class I line-haul locomotives which travel long distances, Class I switcher locomotives which largely 

operate within railyards, and for Shortline and Regional locomotives which generally serve specific 

industries and complex railyards and intermodal terminals. This paper presents the data and 

methodologies used to develop the inventories, the results, and potential improvements. 

Locomotives generally utilize very large diesel combustion engines, resulting in emissions of 

NOx, PM, hydrocarbons, and greenhouse gases. Emissions are regionally distributed from long-distance 

hauling as well as sometimes being highly concentrated in railyards. Along with contributing to 

secondary pollutants such as ozone and PM2.5, which can exceed National Ambient Air Quality 

Standards, locomotive emissions can directly impact sensitive populations near railroad tracks and 

railyards (e.g. schools, hospitals, ‘Environmental Justice’ communities). 

Locomotive emission inventory development tools often vary dramatically between states. 

Except for a few notable exceptions, the resulting inventories generally lack the resolution needed to

support air quality modeling or ‘hotspot’ evaluation and are difficult to combine for cohesive systematic 

analysis. Freight transportation is projected to increase, dramatically in some areas near the East Coast 

due to the 2014 Panama Canal expansion, and technologies and techniques for reducing emissions 

and/or population exposure are available, making these inventories timely and useful to support the safe, 

efficient advancement of the United States railroad system. 

INTRODUCTION 
2 

Rail-related emissions can be important components of inventories used to support atmospheric 

management practices at local, state, regional, and national levels. Previous air quality studies often 

have not data needed to adequately represent this source sector in air quality modeling and planning 1-6

. 

Air protection agencies from twenty-seven states, coordinated through the Eastern Regional 

Technical Advisory Committee (ERTAC) and headed by the Lake Michigan Air Directors Consortium 

(LADCO), identified rail as an important, but poorly characterized emission source so established a 

subcommittee to better quantify and characterize rail-related emissions inventories. The ERTAC Rail 

Subcommittee (ERTAC Rail) had active representation from twelve member states, three regional 

planning offices, and the US EPA (Appendix A). The subcommittee’s goals were to (1) standardize 

agencies’ inventory development methods through a collaborative effort, (2) improve the quality of data 

received and the resulting emission inventories, and (3) reduce the administrative burden on railroad 

companies of providing data. Information on ERTAC Rail, Railroad participation, the Rail industry, and 

effects of rail on air quality are available elsewhere7

With support from the Rail industry and assistance from the ERTAC Rail Data Workgroup 

(Appendix A), ERTAC Rail developed 3 inventories of locomotive emissions as summarized in Table 1. 

The inventories represent locomotive emisisons from Class I line-haul, Class I railyard switchers, and

Shortline (Class III) and Regional Railroads (Class II) and are available at 

http://www.georgiaair.org/airpermit/html/planningsupport/regdev/locomotives/inventories2012.htm 

Table 1. Summary of ERTAC Rail Inventories: U.S. Locomotive Emissions and Fuel Use for either 

2007 or 2008*.

 Fuel Use** (gal/yr) Emissions (tons/yr) 

NOx PM2.5 HC SO2 CO NH3 CO2

Class I*** 

line-haul 3,770,914,002 754,443 23,439 37,941 7,836 110,969 347 42,305k

Class I 

switcher 301,046,290 74,431 2,042 4,867 624 9,230 28 3,367k

Class II 

and III 157,800,000 47,035 1,065 1,737 327 4,631 14 1,765k

*See Appendix B for a description of the year and source of data utilized for each inventory. 

**Locomotive grade diesel 

***Excluding Amtrak and including work train fuel use 

Because of the difficulty in obtaining data and differences in states’ needs for inventory years, 

data sources from both 2007 and 2008 were utilized (Appendix B.) Due to the variability and 

uncertainty in much of the data, the results may be considered applicable for either 2007 or 2008 or 

scaled to more accurately represent a selected year. This paper presents the data and methodologies 

used to develop the three categories of locomotive emission inventories. This set of railroad emission 

inventories should greatly improve our ability to estimate rail-related emissions over large areas and

where locally-collected data is not available. 

The Surface Transportation Board (STB) defines Class I Railroads as having had minimum 

carrier operating revenues of $401.4 million (USD) in 2008. As shown in Table 2, there are 8 Class I 

Railroads operating in the United States, about 33 Regional Railroads (Class II), and approximately 540 

Class III Railroads (Shortlines)8

. While categorized as a Class I Railroad, Amtrak was excluded from 
3 

these inventories because of significant differences in equipment and operation characteristics. Class I 

railroads are required to report fuel use and number of locomotives for both switchers and line-haul 

locomotives to the STB, while Class II and III railroads do not submit data. Line-haul locomotives are 

usually newer, larger locomotives that travel long distances (e.g. between cities) while switcher 

locomotives are generally older, smaller locomotives that mostly operate within railyards, splitting and 

joining rail cars with varying destinations. Shortline railroads often utilize smaller, older locomotives 

than Class I line-haul. While duties are generally segregated, there is not always a hard-line distinction 

and locomotives are occasionally utilized for both hauling and switching. Passenger and Commuter Rail

(including Amtrak), industrial locomotives, and associated non-locomotive equipment are not included 

in these inventories. The railroad emission inventories are segregated by railroad class and function

because of the differences in fleet characteristics, operational patterns (‘duties’), and data availability. 

Class I line-haul activities are the largest source of rail-related emissions, with estimates of Class

I line-haul fuel consumption totals to be from 74 to 84% of all rail sources combined4, 5. For this reason, 

characterizing Class I line-haul emissions were a focal point of the inventory development efforts. 

However, railyards and local and regional railroads can have important impacts on local scale air quality 

and elevated direct exposures. 

Table 2. Class I Railroads, Reported Locomotive Fuel Use, 

and Railroad Fuel Consumption Index (RFCI) 9

. 

Class I Railroads* 

R-1 Reported Locomotive Fuel 

Use (gal/yr) RFCI 

Line-Haul (ton-miles/gal) 

(2007)** 

Switcher 

(2008) 

BNSF 1,393,874,954 52,497,057 883.14 

Canadian National 93,830,751 12,290,022 1190.79 

Canadian Pacific*** 50,320,233 4,594,067 1096.28 

CSX 514,687,186 53,717,674 963.81 

Kansas City Southern 69,787,071 1,816,759 785.89 

Norfolk Southern 463,267,278 32,317,375 865.75 

Union Pacific 1,185,146,529 143,470,336 974.64 

Total 3,770,914,002 300,492,223 929.47 

* Excluding Amtrak 

** Includes work trains 

*** CP’s line-haul fuel use values include 2008 data (rather than 2007) for their Delaware and Hudson 

subsidiary. 

LOCOMOTIVE EMISSIONS INVENTORY DEVELOPMENT METHODS 

Class I Line-Haul Inventory 

Earlier efforts to characterize line-haul railroad emissions relied on highly aggregated activity 

data and generally apportioned annual system-wide fuel use equally across all route miles of track 

operated by a Class I railroad. However, the majority of freight tonnage carried by Class I railroads is 

concentrated on a disproportionately small number of route miles (Figure 1). In addition, emissions 

calculations were previously based on an estimate of annual nationwide-average locomotive fleet mix to

create one set of emissions factors. 
4 

For this inventory, the Class I Railroads allowed ERTAC Rail access under a confidentiality 

agreement to a link-level (single lengths of track) line-haul GIS layer activity dataset managed by the 

Federal Railroad Administration10. Each railroad also provided fleet mix information that allowed 

ERTAC Rail to calculate weighted emission factors based on the fraction of their line-haul fleet meeting 

each Tier level category. The use of this data, largely following a line-haul inventory methodology 

recommended by Sierra Research2, 3, resulted in a link-level line-haul locomotive emission inventory 

using railroad-specific emission factors. This segment-level inventory is nationwide, aggregated to state 

and county level files and can be converted to gridded emissions files for use in photochemical and 

dispersion modeling. Link-level emissions may be provided to third parties for special study requests

pending approval of any Class I railroads operating in the study domain. The calculations are described 

below as a two-part process, first calculating railroad-specific factors and then total emissions per rail 

link. 

Figure 1. US Railroad Traffic Density in 2006.11 MGT is million gross tons. 

1) Calculate Railroad-Specific Factors. 

The EPA provides annual default Emission Factors for locomotives based on characteristic 

operating cycles (‘duty cycles’) and the estimated nationwide fleet mixes for both switcher and line-haul 

locomotives. However, fleet mixes vary from railroad to railroad and, as can be seen in Figure 2, Class I 

railroad activity is highly regionalized in nature and subject to issues of local terrain such as operation 

on plains vs. mountainous areas, which can have a significant impact on fuel consumption and 

emissions. 

As an alternative approach to using a single nationwide set of emission factors, ERTAC Rail 

requested each Class I company to provide a description of their line-haul fleet mix based on Tier rating, 

which each company provided under a confidentiality agreement. An engine’s Tier level is based on the

year the engine was built and determines allowable emission limits (Table 3). 
5 

Figure 2. Class I Railroad Territories in the United States12. 

Table 3. EPA line-haul locomotive Emission Factors by Tier, 1997 standards (grams/gal). Note that the 

new standards released in 2008 did not apply to fleets in the year 2008. 13

PM10 HC NOx CO 

Uncontrolled (pre-1973) 6.656 9.984 270.4 26.624 

Tier 0 (1973-2001) 6.656 9.984 178.88 26.624 

Tier 1 (2002-2004) 6.656 9.776 139.36 26.624 

Tier 2 (2005 + ) 3.744 5.408 102.96 26.624 

Based on values in EPA Technical Highlights: Emission Factors for Locomotives, EPA Office of Transportation 

and Air Quality, EPA-420-F-09-025, April 2009. 

Weighted Emission Factors (EF) per pollutant for each gallon of fuel used (gm/gal or lbs/gal) 

were calculated for each Class I railroad fleet based on its fraction of line-haul locomotives at each

regulated Tier level (Equation 1; Table 3). 

Equation 1 ∑=

=

4

1

( * )

T

iRR iT TRR EF EF f

where 

 EFiRR = Weighted Emission Factor for pollutant i for Class I railroad RR (gm/gal). 
6 

 EFiT = Emission Factor for pollutant i for locomotives in Tier T (gm/gal) (Table 3). 

 There were 4 Tiers of locomotives in the 2008 fleets. 

 fTRR = Fraction of railroad RR fleet in Tier T. 

While engine emissions are variable within Tier categories, this approach likely provides better 

regional estimates than uniformly applying the nationwide average emission factors. This approach 

likely provides conservative emission estimates as locomotive engines are certified to meet or exceed 

the emissions standard for each Tier, although emission levels may increase after certification and actual 

operations may vary widely from the line-haul duty-cycle estimation. 

Other emission factors are not engine specific. For locomotives, PM2.5 is assumed to be 97% of 

PM10

13, and emission factors applied for SO2 and NH3 are 1.88 g/gal 13 and 83.3 mg/gal 14 respectively. 

Greenhouse gases are estimated using emission factors shown in Table 4. Note that non-road engine 

and fuel specific information is sparse for these conversions and that locomotive and marine engines are 

not subject to general non-road fuel or engine standards. 

Table 4. EPA greenhouse gas emission factors for locomotive diesel fuel (grams/gal). 15

CO2 N2O CH4

Locomotive diesel 1.015E4 0.26 0.80 

A Railroad Fuel Consumption Index (RFCI) was also calculated for each Class I railroad using 

their system-wide line-haul fuel consumption (FC) and gross ton-mile (GTM) data reported in their 

annual R-1 reports submitted to the Surface Transportation Board8

 (Equation 2). This value represents 

the average number of GTM produced per gallon of diesel fuel used over their system in a year and 

varies between railroad carriers depending on factors such as fleet mix, system terrain, speeds, 

loading/weight of cargo, train type (e.g., intermodal, unit, and manifest), and operating practices. (Table 

2). 

Equation (2) 

RR

RR

RR FC

GTM RFCI =

where 

RFCIRR = Railroad Fuel Consumption Index (gross ton-miles/gal) per Class I railroad (RR).

 GTMRR = Gross Ton-Miles (GTM), annual system-wide gross ton miles of freight 

 transported per RR. (R-1 Report Schedule 755, Line 104) 

 FCRR = Annual system-wide fuel consumption by line-haul and work trains per RR (gal) 

(R-1 Report Schedule 750, Lines 1 and 6). 

2) Calculate Emissions per Link. 

Emissions of pollutant i per link L (EiL) are calculated by multiplying the gallons of diesel fuel 

consumed by each Class I railroad on the link by that railroad’s weighted Emission Factor for the 

pollutant, and then summing emissions for all Class I railroads operating on that link (Equation 3). This 

approach splits the activity on each link (represented by MGT) evenly between all railroads operating on 

the link. Note that the weighted Emission Factors are converted to tons/gal for these calculations, and 

that variables with units in tons may represent tons of freight hauled (MGT, RFCI) or tons of pollutants 

(EF, E). 
7 

Equation (3) ∑=

















=

N

RR

iRR

RR

L

L

iL EF

RFCI

l

N

MGT

E

1

6

*

*

10*

where 

EiL = Emissions of pollutant i per link L (tons/year). 

N = Number of Class I railroads operating on link L.

MGTL = Millions of Gross Tons hauled per link per year from the FRA database 

(106 tons/yr)9. 

lL = Link length from the FRA database (miles). 

 EFiRR = Weighted Emission Factor for pollutant i per railroad RR (Equation 1; tons/gal). 

 RFCIRR = Railroad Fuel Consumption Index per railroad RR (Equation 2; gross tonmiles/gal). 

Note that approximately 36% of Class I route miles in the United States are shared by more than 

one Class I carrier, a fraction that drops to 26% when neglecting track only shared between one Class I 

freight railroad and Amtrak. Accurately apportioning the specific fractions of tonnage (MGT) per 

carrier per link was considered, but after comparing likely worst-case areas, the difficultly of merging 

carrier-specific MGT with the aggregated FRA MGT dataset was considered too great considering the 

potential gain in accuracy. Where warranted, MGT data may be apportioned more accurately in the 

future. 

Class I Railyard Inventory (‘Switcher’ Locomotives)

Railyard emissions can be important for air quality management in nonattainment areas and 

exposure analysis, as well as in regional analysis and for future transportation and freight planning. 

While there are many unique sources operating in railyards16, switcher locomotives are expected to be 

the largest single source not represented by other emissions accounting techniques. Therefore, as a 

starting point for a comprehensive railyard inventory, this Class I switcher emission inventory was 

developed. It is assumed that estimates for yards of interest, associated equipment and activity, and

smaller railroads could be refined later. This inventory will be useful for regional and some local 

modeling, helps identify where railyards need to be better characterized, and provides a strong 

foundation for future development of a meaningful nationwide Class I switcher emissions inventory. 

The inventory provides a comprehensive overview of where Class I railyards are, who owns 

them, and gives a geographical allocation of switcher emissions based on number of switchers operating

and/or tonnage around/through the yards, and is bounded by what is reported as nationwide switcher fuel 

usage by each Class I railroad. Some results were refined based on yard-specific input by the railroad 

companies that own the yard or from previous specific studies by states. 

While ERTAC Rail represents states east of the Mississippi River, the railroad companies 

specified they wanted this effort to result in a consistent nationwide inventory. ERTAC Rail agreed to 

calculate emissions for all states when the data was available and when additional significant effort was 

not required. Because both the dataset of railyards and switcher fuel use was nationwide in scope, the 

resulting initial railyard inventory is a nationwide, ‘top-down’ derivation. However, railroad companies 

may have different levels and quality of data available, and may have interpreted some data requests 
8 

differently. Also, states are requested to update yards they have detailed information on when possible, 

and a few states (i.e. California) have unique railroad operations and equipment. Therefore, data for

some areas will be more accurate than for others, and locally-derived inventories may be more accurate. 

Yard-specific operations data would greatly improve the representation of emissions6, 17

. 

The development of this nationwide top-down railyard switcher inventory consisted of three main 

activities: 

1) Locate Class I Railyards 

2) Select/Calculate Emission Factors 

3) Estimate Locomotive Activity 

4) Improve Estimates 

1) Locate Class I Railyards. 

 Identification and correct placement of railyards was an important first step, requiring a 

comprehensive electronic dataset. The confidential FRA database used for the Line-haul inventory10 was 

selected because it was the best available database and would provide consistency with the Class I Linehaul inventory. A comparable public database compiled by the Bureau of Transportation Statistics is 

also available10. Data from the public source will not match the confidential data used for this inventory 

exactly but will be very similar. The FRA database has rail links (track lengths) individually identified 

as parts of specific railyards. While there may be discrepancies in how each railroad defined railyard 

links, this dataset appears to identify most Class I railyards in the U.S., and shows a high density of 

yards in the eastern states (Figure 3a and b). For each railyard link, the database gives length, up to 3 

owners and 3 operators, and a Federal Density Code (explained below). 

Figure 3. Class I Railyards in the United States and estimates of (a) Annual NOx emissions and (b) 

Annual PM2.5 emissions from switcher locomotives (tons/yr in 2008). 

(a) 
9 

(b) 

2) Select/Calculate Emission Factors. 

As described in the Line-haul section, the EPA provides annual default emission factors based on 

characteristic operating cycles (‘duty cycles’) and an annual estimated nationwide fleet mix for both 

switcher and line-haul locomotives (i.e. percent of locomotives in each Tier level category). However, 

switcher fleet mix is not uniform from company to company and, as can be seen in Figure 2, Class I 

railroad activity is highly regional. 

As an alternative approach to using the default factors, ERTAC Rail requested each Class I rail 

company to provide a description of their switcher fleet mix based on Tier rating, which each company 

provided under a confidentiality agreement. An engine’s Tier level determines allowable emission 

limits based on the year the engine was built and/or re-manufactured (Table 5). While engine emissions 

are variable within Tier categories, this estimate likely provides a better regional estimate than the

nationwide average. The company-specific system wide fleet mix was used to calculate weighted 

average emissions factors for switchers operated by each Class I railroad, resulting in ranges between

fleet emission factors such as from 6.10 to 6.69 g/gal PM10 and 212.98 to 264.48 g/gal NOx. Emission 

factors for PM2.5, SO2, NH3, VOC, and GHGs are the same as for line-haul locomotives. 

Table 5. EPA switcher locomotive emission factors by Tier, 1997 standards (grams/gal). 

PM10 HC NOx CO 

Uncontrolled (pre-1973) 6.688 15.352 264.48 27.816 

Tier 0 (1973-2001) 6.688 15.352 191.52 27.816 

Tier 1 (2002-2004) 6.536 15.352 150.48 27.816 

Tier 2 (2005 + ) 2.888 7.752 110.96 27.816 

Listed years apply to the year the engine was built. Table based on values from 13. Note that the new standards released in 

2008 did not apply to existing fleets in the year 2008. 
10 

Switchers are assumed to operate 24-hour per day 365 days per year. An evaluation of the 

effects on emissions of variability in operations and in temporal patterns between railyards would be 

very useful for future emission estimates. 

3) Estimate Locomotive Activity. 

 The STB R-1 reports used for the line-haul inventory are also used for the switcher inventory to 

provide consistency (Table 2). There may be inconsistencies between railroads in how fuel use is 

estimated to be apportioned between line-haul and switcher locomotive use, and possibly even in the 

total locomotive fuel use, so these values should be evaluated and may be adjusted in the future. 

However, the use of these reported values provides a good starting point for segregating and allocating 

emissions by individual Class I carriers. 

The next step for inventory development is to allocate switcher fuel use to each railyard. Two 

methods were first applied, one that relies on publicly available line-haul activity (the ‘Dencode’ 

method), and the other using confidential line-haul activity (the ‘MGT’ method.) At this time, Norfolk 

Southern and Kansas City Southern have provided input for use of the MGT method, and the Dencode 

method is applied for the other five railroads. 

The Dencode Method – based on publicly available data 

Each link in both the publicly available BTS database and the confidential FRA database has a 

‘Federal Density Code’ (Dencode) ranging from 1 to 7 assigned based on the cumulative annual freight 

tonnage hauled on the link (track). Total Switcher Fuel Use in each railyard Y (SFUY) is estimated as 

follows: 

First a Switcher Activity Indicator per yard (SAIY) is calculated by multiplying the average 

dencode of the links within a railyard by the sum of the length of the links for that railyard (Equation 4). 

Equation (4) SAIY = ( * )

nY FDCnY ∑ l

where 

 SAIY = Switcher Activity Indicator in Railyard Y 

 nY = number of links identified as part of railyard Y 

 lnY = length of link n in miles 

 FDCn = Federal Density Code (1 to 7) of link n 

Next, this value is then weighted (SAIY’) based on an ownership factor (OF) set between 0 and 1. 

The OF depends on the number of owners listed for each railyard: if there is one owner the OF is set to 

1, if there are two owners the primary owner is set to 0.8 and the secondary is 0.2, and if there are 3 

owners the primary is 0.7, the secondary is 0.2, and the tertiary is 0.1. 

Equation (5) SAIY’ = OFY* SAIY 

Next, the SAIY’ of all railyards belonging to a Class I railroad (RR) were summed, and the 

fraction of the railroads total SAI associated with each railyard was multiplied by the railroads total 

annual switcher fuel use reported in the R-1 (TFURR), resulting in the total Switcher Fuel Use for each 

railyard Y (Equation 6). 
11 

Equation (6) SFUY = RR

RR

Y

Y TFU

SAI

SAI *

'

'

∑

where 

 SFUY = Switcher Fuel Use at railyard Y 

Finally, the SFUY is multiplied by the emission factors described in the previous section to 

obtain annual switcher emissions at each railyard. 

The MGT Method – based on confidential data 

Two railroads, Norfolk Southern and Kansas City Southern (KCS), allowed the use of 

confidential link-level tonnage information and weighting factors to correct skewed estimates to 

improve estimated switcher activity at important yards. Other railroads may also allow the use of this 

technique for their inventories in the future. In addition, KCS provided yard-specific activity 

information. 

The MGT Method also uses the FRA database for railyard identification and link lengths. 

However, rather than using the average dencode per link, confidential annual gross tonnage (MGT) 

hauled per link in the railyard was used to calculate the railyard switcher activity (SAIY). This is 

calculated by replacing FDCn in Equation 4 with link-specific tonnage MGTn (Equation 7). 

Equation (7) SAIY = ) ( *

nY MGTnY ∑ l

where 

 SAIY = Switcher Activity Indicator in Railyard Y 

 nY = number of links identified as part of railyard Y 

 lnY = length of link n in miles 

 MGTnY = million gross tons on link n 

This method provides a more refined comparison between railyards than the use of the 7-

category dencodes; however, is more susceptible to errors for yards where tonnage is not correlated to

switching activity. For example, a yard with large coal trains pulling through used for crews to change 

over would be assigned an overly high level of emissions for switching activity. To account for this, a 

discretionary Switching Activity Factor (SAF) was introduced to allow railroads to roughly weight yards 

with clearly higher or lower levels of switching activity than what results from the mathematical 

allocation. Therefore, SAIY is weighted based on both the ownership factor (OF) as well as the SAF 

(Equation 8). For example, a yard used for crew changes and not switching may have an SAF of 0, 

while a yard at a major interchange between cities may have an SAF of 3. 

Equation (8) SAIY’ = OFY*SAFY* SAIY 

Again, the SAIY’ of all railyards belonging to a Class I railroad (RR) are summed, and the 

fraction of the railroads total SAI associated with each railyard was multiplied by the railroads total 

annual switcher fuel use reported in the R-1 (TFURR), resulting in the total Switcher Fuel Use for each 

railyard Y (Equation 9). 
12 

Equation (9) SFUY = RR

RR

Y

Y TFU

SAI

SAI *

'

'

∑

While the SAF allows estimates of yard-specific emissions to be adjusted, the total level of 

emissions for each railroad, which is based on systemwide fuel use and systemwide emission factors, 

remains unchanged. The MGT method SFUY is also later multiplied by the emission factors described 

in the previous section to obtain annual switcher emissions at each railyard. 

4) Improve estimates. 

In addition to the Switching Activity Factor described above, direct input was also used to 

improve emission estimates for important railyards. Each Class I railroad provided an estimate of 

annual average switcher fuel use (generally much lower than the EPA default of 82,490 gal/yr) as well 

as the name, location, and number of operating switchers for railyards with 8 or more switchers 

operating in ozone or PM2.5 nonattainment areas. Some railroads, Kansas City Southern in particular, 

then provided additional railyard specific data. This directly reported data was used to overwrite the 

dencode or MGT derived emissions estimates for those railyards. 

The difference in estimated fuel use for those railyards was re-allocated (added or removed) 

between the remaining railyards belonging to that Class I railroad. It is important to note that there are 

some discrepancies in how this data was reported for the large railyards by each railroad. For example, 

some railroads reported all switchers located at a railyard while others reported ‘full time equivalent’ 

switchers, meaning the number of switchers normalized to a full working cycle (24-hours per day yearround.) This process should be standardized for future inventory versions. Variability is also introduced 

because ‘switcher’ locomotives can also be used for ‘road work’, meaning they occasionally haul loads 

between yards. 

States also have the option of updating specific railyard emissions estimates. Because this 

inventory is derived ‘top-down’, local studies and familiarity with specific railyards is expected to 

provide better estimates, which can be used to adjust this inventory. Care must be taken to ensure the 

other railyard estimates are adjusted to account for increases or decreases in estimated fuel use per yard. 

Shortline and Regional Railroads (Class II and III)

There are approximately 570 Class II and III Railroads operating in the United States, around 

450 of which are members of the American Shortline and Regional Railroad Association (ASLRRA)8. 

In general, while information on Class II/III link locations and many fleet characteristics are available 

online, a significant effort would be required to compile this data into a usable format and check the data 

for reliability. In addition, the Class II and III sectors of the railroad industry have been in considerable 

flux since partial deregulation from the 1980 Staggers Act. States with relatively large numbers of Class 

II and III railroads, such as Maine, Pennsylvania, North Carolina, and Massachusetts, have independent

surveys and emission inventory estimates available, but no regional or national level cohesive electronic 

datasets have been previously developed. 

Class II and III activities account for an estimated 4% of the total locomotive fuel use in the 

combined ERTAC inventories and for approximately 32% of the industry’s national freight rail 

mileage18. These railroads are widely dispersed, though more concentrated in the eastern United States 
13 

(Figure 4), and often utilize older, higher emitting locomotives than their Class I counterparts. These 

railroads provide services to industries requiring consistent transportation of large amounts or very 

heavy freight, small towns, and/or provide switching and terminal services at complex rail and 

intermodal intersections (Figure 5). 

Figure 4. Shortline and Regional Railroads (Class III and II) in the United States (based on GIS data 

from reference 10). 

Figure 5. Carloads shipped by Shortline and Regional Railroads by commodity group8 

To calculate a nationwide Class II/III emissions inventory, ERTAC Rail first surveyed existing 

data sources, compared states’ methods and data used for existing inventories, and contacted members 

of the Class II and III Railroad communities for guidance, including the ASLRRA, the FRA, and 
14 

Genesee & Wyoming, RailAmerica, and Omnitrax (large holding companies of Class II and III 

railroads). In particular, Mr. Steve Sullivan from ASLRRA and Mr. David Powell from Genesee & 

Wyoming were able to provide significant assistance in identification of an appropriate nationwide 

dataset of Class II and III railroads with links and total locomotive fuel use, the development of a 

calculation method, and guidance on appropriate assumptions such as fleet average locomotive Tier 

classification. Data sources, calculations, and assumptions used to develop the resulting inventory are 

described below. 

This ERTAC Rail Class II/III inventory provides a cohesive nationwide inventory with data for 

where Shortline and Regional Railroads operate and who owns them, and provides a comprehensive 

geographical allocation of their locomotive emissions bounded by what is reported as total nationwide 

Class II/III fuel usage by the ASLRRA. This inventory will be useful for regional and some local 

modeling, helps identify where railroads may need to be better characterized, and provides a strong 

foundation for future development of a more accurate nationwide Shortline and Regional railroad 

emissions inventory. 

1) Locate Class II and III Railroads. 

 Identification and correct placement of Class II and III railroads was an important first step, 

requiring a comprehensive electronic dataset. The FRA database used for the Class I inventories 

identifies links as owned or operated by specific Shortline or Regional Railroads using “Reporting 

Marks”, which are brief identification abbreviations. The full list of Reporting Marks is included with 

the inventory. The locations of these links with associated data including reporting mark, railroad name, 

class, number of links and route miles owned and/or operated, and total route miles of links were 

extracted by ERTAC Rail (Matt Harrell, Appendix D.) While this dataset contains confidential data for

the Class I railroads, the geographical allocation of Class II and III links (Figure 4) and related 

information is public10, as is the similar Bureau of Transportation Statistics database10. 

2) Select/Calculate Emission Factors. 

While some Class II and III railroads purchase more recent locomotives, locomotives often serve 

30 to 40 years in Class I line-haul service before being transferred to switching service or sold to Class 

II or III railroads. Through guidance from the Class II/III Railroad community, it was agreed that the 

EPA Non-regulated (pre-1973) emission factors13 best represent most operating Class II and III 

locomotives. In addition, although the fuel use and route miles data obtained represent both switching 

and line-haul activities by the Class II and III railroads, the US EPA line-haul duty cycle was selected as 

most representative along with the “Small Line-Haul” conversion factor13 to obtain gm/gal emission 

factors for hydrocarbons (HC), oxides of nitrogen (NOx), particulate matter (PM),and carbon monoxide 

(CO) (Table 6). Emission factors for PM2.5, SO2, NH3, VOC, and GHGs are the same as for line-haul 

locomotives. 

Table 6. Emission factors over the standard operating line-haul duty cycle using a conversion factor of 

18.2 bhp-hr/gal 13.

Line-Haul (gm/gal) 

HC NOx PM CO 

Non-regulated (pre 1973) 8.736 236.6 5.824 23.296 
15 

3) Calculate Emissions. 

The ASLRRA compiles data from the Class II and III railroads every few years8

, including total 

industry fuel use for locomotives and total Class II/III Route Miles. The FRA dataset also provides 

route miles. These values can be used to calculate an average Fuel Use Factor (FUF) for the industry 

(Equation 10). 

 

Equation (10) 

mile

gal

miles

gal

TotalClassII IIIRouteMiles

TotalIndustryFuelUse FuelUseFactor

FRA

ASLRRA 2814 64.

367,52

157 800, 000,

/

= = = 

Some data was available from the ASLRRA to distinguish between the Shortline and Regional 

Railroad fuel use and miles of track, however the resulting fuel efficiency factors were not intuitively 

correct so ERTAC Rail chose to keep their emissions inventories combined until the discrepancies can 

be improved or explained. 

ERTAC Rail chose to use the Total Class II/III Route Miles values with non-zero activity from 

the FRA dataset for this calculation, 52,367 miles, as shown. This way, if a railroad is known to have 

ceased operations, those route miles are not counted while the total fuel used estimate remains the same. 

In addition, this dataset was available in GIS format for mapping purposes, the data is also used for the 

Class I line-haul and switcher inventories, and it is part of a more comprehensive, managed inventory.

For comparison, ERTAC Rail has actual fuel use data and route miles for approximately 50 

shortline railroads, which result in an overall average FUF of 2560.10 gal/mile, very close to the 

nationally calculated FUF. The average of the independently calculated FUFs in the inventory is 

3001.09 gal/mile, with the maximum being 15953.78, the minimum being 67.97, and a standard 

deviation of 3393.08 gal/mile. As can be seen, while the averages are in good agreement, there is a wide 

range of potential individual FUFs per railroad which can depend on many factors such as frequency of 

trips, tonnage hauled, terrain, distance, locomotives used, and others. This wide potential range 

indicates the importance of using specific fuel use data when possible. There are also discrepancies 

between the FRA route miles assigned to railroads and route miles reported by the railroads. Because of 

the GIS linkages available with the FRA database, the FRA route miles rather than reported route miles

are used in the inventory. These should also be verified when possible and, if necessary, corrected both 

in the FRA database and the emissions inventory. 

The Fuel Use Factor calculated for use in this inventory (2814.64 gal/mile) was multiplied with 

the route miles listed for each Class II and III railroad in the FRA database, resulting an estimate of 

gallons of fuel used in 2008 for each railroad. The annual gallons of fuel used were then multiplied with 

pollutant emission factors for a mass of pollutant emitted for the year. 

Further modifications were made to the estimates to reflect actual fuel use collected for specific 

class II/III railroads, including entries of ‘0’ for railroads known to be out of operation. In particular, 

specific fuel use data was entered for railroads owned by Genesee & Wyoming and for some Class III 

railroads operating in Pennsylvania, Massachusetts, and North Carolina. These modifications were 

accounted for in the Fuel Use Factor calculation applied to the remaining railroads so that the national 

total fuel use is equal to the total estimate by the ASLRRA (157,800,800 gal) and the Fuel Use Factor is 

calculated only using fuel and track data for railroads with no known fuel use information. 
16 

Limitations, Conclusions, and Future Work 

It must be noted that freight-related rail activity is not always routine and no annual emissions 

inventory will ever be able to capture the innate variability of the source. However, as other large 

emission sources are reduced, and if rail activity increases as expected, it is important to include the best 

emission estimates possible of these sources for air quality and epidemiological analysis. In the future, 

on-line data loggers and other tracking technologies, combined with ambient studies and detailed 

modeling, will hopefully provide more insight to the emissions of locomotives and other railyard 

sources. 

This is a first generation inventory, and many limitations exist. For the Class I inventories, early 

ERTAC Rail discussions concluded that link-level tonnage was the most important data to obtain, while 

other variables such as track grade and track speed could not be addressed at this time. ERTAC Rail 

calculated railroad-specific fleet-averaged emission factors rather than applying the estimated national 

average; however, it is recognized that emissions from individual engines are highly variable even 

within Tier categories depending on variables such as the specific locomotive model, operation cycle, 

and conditions of operation. Future evaluation of emission variability within Tiers and between certain 

types of operation and locations would be valuable. There is also likely significant variability in actual 

switching duty-cycles and, potentially, in the number of switchers operating at some railyards at 

different times of the year. ‘Road-switching’, or the use of what are considered switching locomotives 

to move between nearby yards, should be addressed in either this or the ERTAC line-haul inventory. 

Major areas for future improvement of the Class II and III inventory include distinguishing 

between switching and hauling operations and updating fleet Tier characteristics where appropriate. 

More accurate annual fuel use estimates, rather than using the estimated Fuel Use Factor would greatly

improve the inventory. For example, 2006 Class II/III fuel use reported to the ASLRRA was 309 

million gallons, almost double what was reported only two years later in 2008. It is unlikely that the 

industry halved fuel use in two years, but no other activity indicators have been found for comparison. 

Another area of uncertainty that can be improved is estimates of temporal variability. Emissions 

inventory preparation guidance from the U.S. EPA describes locomotive activity as constant throughout 

the year (e.g. no daily, weekly, or seasonal variability), though weekly or seasonal variation is highly 

likely for the Class II and III lines. States or other areas with local, direct Class II and III data including 

temporal activity, fleet characteristics, or annual fuel use should use that information in place of this 

inventory. This inventory was designed to incorporate refinements from industry or state agency 

representatives, and we request that any data collected be submitted to ERTAC Rail so that the 

inventory can be continuously improved. 

An uncertainty study on the data used for this inventory, including the R-1 reported fuel use for 

Class I line-hauls and, in particular, switchers, the confidential link-level tonnage data for Class I linehaul operations, and the duty-cycle estimates for line-haul and switcher operations would help in 

evaluating the quality of this inventory. Additionally, the uncertainty contributed by the use of tonnage 

hauled as an indicator of the amount of switching activity. Localized studies should examine how 

shared tracks are apportioned between multiple carriers in their domain. 

Emissions inventory preparation guidance from the U.S. EPA describes locomotive activity as 

relatively constant throughout the year (e.g. no daily, weekly, or seasonal variability); however, actual 

activity levels do vary seasonally and annual averaging may dilute or exaggerate concentrations during

pollution episodes. ERTAC Rail and the Class I railroad community had some discussions addressing if 
17 

incorporating more specific fleet mix or monthly or seasonal variation may be worthwhile, and these 

topics should be looked into further. 

Finally, it is important to reiterate that the link-level MGT data maintained by the FRA is 

proprietary and can only be released to agencies/groups outside the FRA with the express permission of

each Class I railroad. It is possible that one or more Class I railroads could withhold permission for 

access, but data for specialized studies may be provided if requested. This database can also be 

improved by better distinguishing between haulage and trackage rights, and by apportioning tonnage 

hauled on links to specific carriers. 

ACKNOWLEDGMENTS 

We would like to thank the ERTAC Rail Data Workgroup and the ERTAC Rail Subcommittee for their 

participation in the development of these inventories (Appendix A), as well as Raquel Wright of the 

Federal Railroad Administration, Richard Billings of ERG, and David Powell of Genesee & Wyoming, 

Inc. 

REFERENCES 

1. “Documentation for Aircraft, Commercial Marine Vessel, Locomotive, and Other Nonroad 

Components of the National Emissions Inventory, Volume I – Methodology”; EPA Contract 

No.: 68-D-02-063. Prepared for the US EPA Emissions, Monitoring and Analysis Division by 

Eastern Research Group (ERG) for E.H. Pechan & Associates, Inc. Sept. 2005. 

ftp://ftp.epa.gov/EmisInventory/2002finalnei/documentation/mobile/2002nei_mobile_nonroad_

methods.pdf. Related documents at 

ftp://ftp.epa.gov/EmisInventory/2002finalnei/documentation/mobile/2002nei_mobile_nonroad_tr

ain.pdf 

2. “Revised Inventory Guidance For Locomotive Emissions”; Report No. SR2004-06-01. Prepared 

for Southeastern States Air Resource Managers (SESARM) by Sierra Research Inc. June 2004. 

http://www.metro4-sesarm.org/pubs/railroad/FinalGuidance.pdf 

3. “Research Project: Development of Railroad Emission Inventory Methodologies”; Report No. 

SR2004-06-02. Prepared for Southeastern States Air Resource Managers (SESARM) by Sierra 

Research, Inc. June 2004. http://www.metro4-sesarm.org/pubs/railroad/FinalMethodologies.pdf 

4. “Draft LADCO 2005 Locomotive Emissions”. Prepared for Lake Michigan Air Director 

Consortium by Environ Feb 2007. 

http://www.ladco.org/reports/technical_support_document/references/ladco_2005_locomotive_e

missions.021406.pdf 

5. “NYSERDA Clean Diesel Technology: Non-Road Field Demonstration Program, Development 

of the 2002 Locomotive Survey for New York State”; Agreement Number 8958. Prepared for the 

New York State Energy Research And Development Authority (NYSERDA) by Southern 

Research Institute Feb. 2007. 

http://www.nyserda.org/publications/LocomotiveSurveyReportwithAppendices.pdf

6. Gould, G..and Niemeier, D. “Review of Regional Locomotive Emission Modeling and the 

Constraints Posed by Activity Data.” Transportation Research Record: Journal of the 

Transportation Research Board, No. 2117, Transportation Research Board of the National 

Academies, Washington, D.C., 2009, pp 24-32. 
18 

7. Bergin, M., Harrell, M., McDill, J., Janssen, M, Driver, L., Fronczak, R., Nath, R. and D. Seep. 

"ERTAC Rail: A Collaborative Effort in Building a Railroad-Related Emissions Inventory 

Between Eastern States Air Protection Agencies and Participation with the Railroad Industry," 

18th Annual International Emission Inventory Conference. Baltimore, MD. April 14 - 17, 2009. 

Paper and presentation available at: 

http://www.epa.gov/ttn/chief/conference/ei18/session6/bergin.pdf

8. American Short Line and Regional Association (ASLRRA) 2008 Fact Book. Available at 

www.alsrra.org. 

9. Surface Transportation Board R-1 Reports, available at:

http://www.stb.dot.gov/stb/industry/econ_reports.html. 

10. Confidential database was provided with assistance from Raquel Wright of the Federal Railroad 

Administration. Similar public data providing ranges of tonnage hauled rather than link-level 

tonnage is available from the Bureau of Transportation Statistics in the NTAD 2009 shapefile 

data (data is representative for the year 2007): 

http://www.bts.gov/publications/national_transportation_atlas_database/2009 . 

11. US DOT Bureau of Transportation Statistics’ 2008 National Transportation Atlas Database. 

12. Freight Railroads in the United States 2008. Association of American Railroads. Available at: 

http://www.aar.org/~/media/AAR/InCongress_RailroadsStates/2008unitedstates.ashx . 

13. EPA Technical Highlights: Emission Factors for Locomotives, EPA Office of Transportation 

and Air Quality, EPA-420-F-09-025, April 2009. 

http://www.epa.gov/otaq/regs/nonroad/locomotv/420f09025.pdf 

14. “Estimating Ammonia Emissions From Anthropogenic Nonagricultural Sources”, Draft Final 

Report. Prepared for EPA/STAPPA-ALAPCO Emission Inventory Improvement Program by 

E.H. Pechan & Assoc. April 2004. Supported by personal communication (5/6/2010) with Craig 

Harvey, US EPA, OTAQ, and Robert Wooten, NC DENR. 

http://www.epa.gov/ttnchie1/eiip/techreport/volume03/eiip_areasourcesnh3.pdf

15. “Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2005”. EPA 430-R-07-002, 

Annex 3.2, U.S. Environmental Protection Agency April 2007. Web site: 

http://www.epa.gov/climatechange/emissions/usinventoryreport.html. 

16. Douglass, B., Heiken, J., Rubenstein, G. “Characterization and Breadth of Rail Yard Specific 

Inventories”. 19th Annual International Emission Inventory Conference. San Antonio, TX. 

September 27- 30, 2010. 

17. Ireson, R.G., Germer, M.J., and Schmid, L.A. “Development of Detailed Railyard Emissions to 

Capture Activity, Technology, and Operational Changes”. U.S. EPA, 14th Annual International 

Emission Inventory Conference. Las Vagas, NV. April 11 - 14, 2005. 

18. Freight Railroads in the United States 2008. Association of American Railroads (AAR). From: 

http://www.aar.org/~/media/AAR/InCongress_RailroadsStates/2008unitedstates.ashx . Also An 

Overview of America's Freight Railroads, Oct 2011, AAR. From: 

http://www.aar.org/~/media/aar/BackgroundPapers/Overview%20of%20US%20Freight%20RRs%20October%2019%202011.ashx
19 

APPENDICES 

Appendix A 

REPRESENTATIVE ORGANIZATION 

ERTAC Rail Data Workgroup

Matt Harrell IL EPA 

Michelle Bergin (Co-Chair) and Byeong Kim GA EPD 

Mark Janssen (Co-Chair) LADCO 

Julie McDill and Patrick Davis MARAMA 

Laurel Driver US EPA OAQPS 

Robert Fronczak AAR 

Steven Sullivan ASLRRA 

Rick Nath CSX 

David Seep and Lyle Staley BNSF 

Ken Roberge CPR 

Carl Akins and Peter Conlon KCS 

Erika Akkerman CN 

M. John Germer UP 

Brent Mason and Richard Russell NS 

Joanne Maxwell Amtrak 

ERTAC Rail Subcommittee

1 Allan Ostrander MI Dept. of Environ. Quality 

2 Amanda Carter AL Dept. of Environ. Manag. 

3 Ashley Mixon SC Dept. of Health and Environ.Control 

4 Bob Wooten NC Dept. of Environ. and Natural Resources 

5 Carla Bedenbaugh SC Dept. of Health and Environ. Control 

6 Chad Wilbanks SC Dept. of Health and Environ. Control 

7 Dennis McGeen MI Dept. of Environ. Quality 

8 Douglas Malchenson PA Dept. of Environ. Protection 

9 Eric Zalewsky NY Dept. of Environ. Conserv. 

10 Grant Hetherington WI Dept. of Natural Resources 

11 Jim Boylan GA Environ. Protection Div. 

12 Julie McDill (Co-chair) Mid-Atlantic Regional Air Management Assoc. 

(MARAMA) 

13 Kelley Matty PA Dept. of Environ. Protection 

14 Kevin McGarry NY Dept. of Environ. Conserv. 

15 Laurel Driver US EPA OAQPS 

16 Lisa Higgins ME Dept. of Environ. Protection 

17 Mark Janssen (Co-chair) ERTAC/ Lake Michigan Air 

Directors Consortium (LADCO) 

18 Matthew Harrell (GIS lead) IL Environ. Protection Agency 

19 Michelle Bergin (Co-chair) GA Environ. Protection Division 

20 Mike Koerber LADCO 

21 Pat Brewer Visibility Improvement State and Tribal 

Association of the Southeast (VISTAS) /ASIP 
20 

22 Richard Dalebout MI Dept. of Environ. Quality 

23 Sam Long IL Environ. Protection Agency 

24 Stacy Allen MO Dept. of Natural Resources 

25 Tracy Anderson AL Dept. of Environ. Manag. 

26 William Nichols OH Environ. Protection Agency 

Appendix B: Source and Year of Data Utilized for Each Inventory 

Data Year Source 

Class I Line-Haul

Annual Line-Haul Fuel Use 

and Gross Ton-Miles 2007 STB R-1 Reports (CP data for D&H is for 2008.) 

Line-haul fleet mix for 

emission factors 2008 Each Class I railroad 

Link-level tonnage 2007 FRA confidential database 

Class I Railyards (Switcher Locomotives) 

Annual Switcher Fuel Use 2008 R-1 Reports 

Switcher fleet mix for 

emission factors 2008 Each Class I railroad 

Link-level tonnage or 

Density Code (for activity 

estimate) 

2007 FRA confidential database 

Class II and III Locomotives 

Annual Total Fuel Use 2008 ASLRRA Annual Report (2008) 

Track length and railroad 2007 FRA confidential database 

Estimated fleet mix for 

emission factors 

Discussions with ASLRRA and 

Class II and III representatives. 

Appendix C: Railroad Companies Operating in the United States 

Railroad 

Class I 

BNSF 

Canadian National 

Canadian Pacific*** 

CSX 

Kansas City Southern 

Norfolk Southern 

Union Pacific 

Amtrack 

*Regional (Class II) 
21 

Mileage 

Alabama and Gulf Coast Railway 435 

Alaska Railroad 506 

Buffalo and Pittsburgh Railroad 699 

Central Oregon and Pacific Railroad 447 

Dakota, Missouri Valley and Western Railroad 534 

Florida East Coast Railway 386 

Great Lakes Central Railroad 396 

Indiana Rail Road 602 

Indiana and Ohio Railway 692 

Iowa Interstate Railroad 608 

Kansas and Oklahoma Railroad 869 

Kyle Railroad 554 

Missouri and Northern Arkansas Railroad 583 

Montana Rail Link 905 

Montreal, Maine and Atlantic Railway 527 

Nebraska Kansas Colorado Railway 559 

New York, Susquehanna and Western Railway 357 

Northern Plains Railroad 486 

Paducah and Louisville Railway 290 

Pan Am Railways 1165 

Portland and Western Railroad 587 

Providence and Worcester Railroad 568 

Red River Valley and Western Railroad 575 

San Joaquin Valley Railroad 351 

South Kansas and Oklahoma Railroad 398 

Texas Northeastern Railroad 665 

Texas Pacifico Transportation 393 

Utah Railway 430 

Wheeling and Lake Erie Railway 878 

Wisconsin and Southern Railroad 837 

Shortline (Class III)

See www.aslrra.org/our_members/Railroad_Members or 

http://www.railsusa.com/links/Shortline_Railroads/

* These railroads were classified as regional by the AAR in 2007 as reported in Wikipedia 

(http://en.wikipedia.org/wiki/Regional_railroad#cite_note-2 , accessed Oct. 7, 2011.) Railroads known to have 

been purchased by Class I railroads after 2007 have been removed from this list. 

Appendix D. ERTAC – Class 2/3 Shapefile Documentation (Matt Harrell, 13 Jul 2009) 

Introduction 

This document outlines the methods and procedures used to compile a shapefile representing the links in 

the FRA 1:100,000 railroad dataset that are owned or operated by Class II and III railroad companies. It 

is important to note that there is a considerable amount of overlap between the Class II’s and III’s and 

the Class I and passenger railroads. Class II’s and III’s can operate on Class I or passenger rail links and 

vice versa. Although the final shapefile specifically represents Class II and III links, there are many 

Class I and passenger railroads represented as well. 
22 

Procedure 

1. Started with all proprietary FRA links where “NET = ‘M’ and “STCNTYFIPS” <> ‘ ‘ (this 

definition query selects all active mainline links located within the United States). 

2. Ran 12 queries, one for each ownership and trackage rights field, to select all links not 

associated with a Class I freight railroad or Amtrak and not containing a null value (e.g., 

"RROWNER1" <> 'AMTK' AND "RROWNER1" <> 'BNSF' AND "RROWNER1" <> 'CN' 

AND "RROWNER1" <> 'CPRS' AND "RROWNER1" <> 'CSXT' AND "RROWNER1" <> 

'KCS' AND "RROWNER1" <> 'NS' AND "RROWNER1" <> 'UP' AND "RROWNER1" <> 

' '). The first query was setup as a new selection. Each of the 11 subsequent queries were 

setup to add records to initial set of records. 26,261 links were selected and exported to a 

new shapefile. 

3. Due to the multitude of railroad codes used to represent commuter rail operations across the 

country, additional processing was required to remove any links that were not operated by a 

Class II or III freight railroad. Each commuter railroad was queried out of the new shapefile 

and the links analyzed to eliminate all links where no Class II or III operations were 

occurring. The following commuter rail operations were evaluated: NJT (New Jersey 

Transit), MNCW (Metro-North Commuter Railroad), LI (Long Island Railroad), CDOT 

(Connecticut DOT), MBTA (Massachusetts Bay Transportation Authority), SEPA 

(Southeastern Pennsylvania Transportation Authority), MARC (Maryland Area Rail 

Commuter), VRE (Virginia Railway Express), MTRA (Northeastern Illinois Regional 

Commuter Railroad), CSS (Northern Indiana Commuter Transportation District), DART 

(Dallas Area Rapid Transit), SCRA (Southern California Regional Rail Authority – including 

also SCAX, LACM, LAPT, and LATC), TCRA (South Florida Regional Transportation 

Authority), PJPB (Caltrain), and ACE (Altamont Commuter Express). Approximately 1581 

links were identified with no Class II or III operations and were deleted from the Class 2/3 

shapefile. 

4. The remaining Class II and III links were then compared to the regional maps contained in 

the July-August issue of The Official Railway Guide to assess the completeness of the Class 

2/3 shapefile. Six specific edits were made to the shapefile to correct the most glaring errors: 

1) BMLP links deleted (Black Mesa & Lake Powell, an electric coal hauling railway in 

Arizona); 2) DSNG links deleted (Durango & Silverton steam tourist railroad in Colorado; 3) 

CIC haulage rights links on CN from Chicago to Omaha deleted; 4) DMIR links deleted 

(Duluth, Missabe & Iron Range, now owned and operated by CN in Minnesota; 5) EVWR’s 

ex-CSXT links coded from Evansville, IN to Okawville, IL (Evansville Western Railroad); 6) 

INRD ex-CP links coded from Chicago, IL to Louisville, IN (Indiana Rail Road). 

5. During the course of reviewing the FRA dataset, 555 “active” links were found to have no 

ownership or trackage rights codes. 1005 links have no codes listed in the 3 ownership 

fields. In most cases these links are very short and scattered across the country. Only the 

links representing the EVWR and INRD spanned large distances and were fixed. The other 

problem links were deemed to be insignificant. A listing of these links will be provided back 

to the FRA to assist with their coding in 1:100K railway shapefile. 
23 

KEY WORDS 

Locomotive emissions 

Railroad emissions 

Air quality 

Nonroad emissions 

Emissions inventory 

Air quality modeling