LOCOMOTIVE EMISSION 

STANDARDS

Regulatory Support Document

United States Environmental Protection Agency

Office of Mobile Sources

April 1998
NOTE TO READERS

This document is a revised version of the December 1997 Regulatory

Support Document that was placed in the public docket at the time of

signature. This version includes editorial revisions, corrections, and some

additional information. The technological feasibility, environmental, and

economic analyses are unchanged in content. The electronic version of

this document also contains tables and figures that were included in the

hard copy of the December 1997 document, but were not included in the

electronic version.
Table of Contents

Chapter/Section Page

1.0 Industry Background ............................................ 1

1.1 Locomotive Manufacturing .................................... 1

1.2 Railroads ................................................... 1

1.3 Locomotive Remanufacturers and Suppliers ...................... 4

1.4 Leasing .................................................... 5

1.5 Locomotive Safety Regulations ................................. 7

1.6 Commercial Role of Railroads .................................. 7

1.7 Environmental Impacts of a Modal Shift . . . . . . . . . . . . . . . . . . . . . . . . 10

2.0 Locomotive Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.1 Energy Supply Sources for Locomotives . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2 Hotel Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.3 Types of Locomotives and Locomotive Design Features . . . . . . . . . . . . 12

2.4 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.5 Replacement Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.6 Remanufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.0 Emission Reduction Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.1 Locomotive Pollutants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.2 Locomotive Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.3 Emission Reduction Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.4 Expected Availability of Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

3.5 Adjustments for Ambient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.6 Reliability and Durability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.0 Emission Standards and Supporting Analyses . . . . . . . . . . . . . . . . . . . . 49

4.1 Duty-Cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4.2 Useful Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

4.3 Baseline Emission Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

4.4 Emission Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.5 Feasibility and Compliance with Standards . . . . . . . . . . . . . . . . . . . . . . 66
5.0 Test Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.1 Locomotive Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.2 Test Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

5.3 Sampling and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

5.4 Fuel Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

5.6 Atmospheric Conditions During Testing . . . . . . . . . . . . . . . . . . . . . . . . . 86

5.7 Other Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

6.0 Emission Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

6.1 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

6.2 Class I Railroad Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

6.3 Class II and III Railroad Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

6.4 Passenger Railroad Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

6.5 Summary of Environmental Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 102

7.0 Costs and Cost-effectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

7.1 Initial Cost Increase for Locomotives . . . . . . . . . . . . . . . . . . . . . . . . . . 106

7.2. Incremental Operating Cost Increases . . . . . . . . . . . . . . . . . . . . . . . . 115

7.3. Total Program Costs and Cost-effectiveness . . . . . . . . . . . . . . . . . . . . 118

APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

APPENDIX A Locomotive Remanufacture Mileage Data from AAR

APPENDIX B Locomotive Emission Data by Throttle Notch

APPENDIX C Calculation of Baseline Locomotive Emission Rates

APPENDIX D Locomotive Smoke Emissions

APPENDIX E Compliance Margins for On-Highway HDDEs

APPENDIX F Supplementary Cost-Effectiveness Data

APPENDIX G Results of SwRI Testing for EPA

APPENDIX H Graphical HC and CO Data

APPENDIX I Environmental Analysis

APPENDIX J Terms and Abbreviations Used in the Rulemaking

APPENDIX K Calculation of Weighting Factors for ABT Credits

APPENDIX L Exclusion of Pre-1973 Locomotives

APPENDIX M NOx Concentrations as a Function of Test Sequence

APPENDIX N 1995 Emission Inventory Data

APPENDIX O Corrections to Environmental Analysis

APPENDIX P Conversion of Emission Rates to g/kW-hr
1

1.0 Industry Background

The regulations for locomotives and locomotive engines are expected to directly

impact four industries. These industries are: 1) manufacturers of locomotives and locomotive engines (original equipment manufacturers (OEMs)); (2) owners and operators

of locomotives (railroads); 3) remanufacturers of locomotives and locomotive engines

(OEMs, railroads, independent remanufacturers); and 4) suppliers of locomotive parts

(OEMs, railroads, independent remanufacturers, parts manufacturers). A brief

overview of these directly impacted industries follows, along with descriptions of the

general economic impact of railroads on the nation and current regulation of railroads.

1.1 Locomotive Manufacturing

Locomotives used in the United States are primarily produced by two

manufacturers: the Electromotive Division of General Motors (EMD) and General

Electric Transportation Systems (GETS). EMD manufactures its locomotives primarily

in London, Ontario and their engines in La Grange, Illinois. The GETS locomotive

manufacturing facilities are located in Erie, Pennsylvania, while their engine

manufacturing facilities are located in Grove City, Pennsylvania. These

manufacturers produce both the locomotive chassis and propulsion engines. They also

remanufacture engines. MotivePower Industries (formerly MK Rail Corporation) has

produced some locomotives using engines manufactured by Caterpillar, Inc. The

Peoria Locomotive Works also manufactures locomotives using Caterpillar Engines,

and Republic Locomotives manufactures locomotives powered by Detroit Diesel

Corporation engines. The Cummins Engine Company, Inc. also produces engines

which may be used in locomotives.

1.2 Railroads

In the United States, freight railroads are subdivided into three classes based

on annual revenue by the Federal government's Surface Transportation Board (STB).

The STB is an adjudicatory body that was formed in 1966 to settle disputes and

regulate the various modes of surface transportation within the U.S. Organizationally

a part of the Department of Transportation, the STB deals with railway rate and

service issues, railway restructuring and various other issues, including classification

of railroads. (STB regulations for the classification of railroads are contained in 49

CFR Chapter X.) In 1994 the STB classified a railroad as a Class I railroad if its

annual revenue was $255.9 million or greater, as a Class II railroad if its annual

revenue is between $20.5 and 255.8 million, and as a Class III railroad if its annual

revenue is less than $20.5 million. The Class I railroads are the nationwide, longdistance, line-haul railroads which carry the bulk of the railroad commerce. In 1994,

there were 12 Class I railroads operating in the U.S. Due to recent mergers, there are

currently 9 Class I freight railroads operating in the country. Class I railroads

presently operate approximately 21,000 locomotives in the U.S. Class I railroads
 "Regional railroad" and "local railroad" are terms used by AAR that are similar, but not 1

identical, to "Class II" and "Class III", respectively. 

 "Locomotive Data for Small Railroads," Memorandum, Charles Moulis, U.S. EPA, to 2

public docket A-94-31, December 5, 1997.

2

account for over 90 percent of the ton-miles of freight hauled annually and consumed

3.60 billion gallons of diesel fuel in 1996, which is about 91 percent of all locomotive

fuel used in the U.S. Of these, the five largest Class I railroads, BNSF, CSX, Conrail,

Norfolk Southern, and Union Pacific, account for the vast majority of the Class I

locomotives currently in service in the U.S. (These five will soon be four, as Conrail is

absorbed by CSX and Norfolk Southern.)

Statistics compiled by the Association of American Railroads (AAR) and the

American Short Line Railroad Association (ASLRA) show that there are approximately

530 Class II and III railroads (not including commuter and insular railroads). A more

detailed breakdown of these can be found in Table 1-1. They consist primarily of

regional and local line-haul and switching railroads , which operate in a much more 1

confined environment than do the Class I railroads. For example, the average length

of haul for a regional railroad is 167 miles, while the average length of haul for a local

line-haul railroad is 41 miles (as opposed to an average of about 800 miles for a Class

I). Class II and III railroads operate approximately 4,200 locomotives. All but about 2

400 of these are owned by the operating railroad. Over 85 percent of the locomotives

owned by the Class II and III railroads were originally manufactured prior to 1973.

Class II and III railroads use about 215 million gallons of fuel annually, about 6

percent of the total used by locomotives. These last two facts indicate that Class II and

III railroads are responsible for less than one percent of all emissions from post-1972

locomotives.

Some of the smaller railroads are owned and operated by Class I railroads, many

of which are operated as formal subsidiaries for financial purposes, but are run as

standalone entities. In 1995, there were 222 local line-haul railroads and 253

switching and terminal railroads, including subsidiaries (regional and local railroads

may also have subsidiaries). A few of these are publicly held railroads and some are

shipper-owned. Insular in-plant railroads are not included in this total. ASLRA

estimated that there are probably about 1,000 insular railroads in the U.S. These

railroads are not common carriers, but rather are dedicated to in-plant use. They

typically operate a single switch locomotive powered by an engine with less than 1000

hp. Such locomotives typically use a few thousand gallons of diesel fuel each year, and

thus are not a particularly significant source of emissions.
 "Railroad Ten Year Trends", Association of American Railroads, 1995. 3

 Does not include all-electric railroads. 4

 Does not include insular railroads. 5

3

Table 1-1

Profile of Railroad Industry - 1995 3

Type of Number of Year-end

Railroad Railroads Employees

Class I Freight Railroad 9 185,762

Class I Subsidiaries 25 3,570

National Passenger Railroads 1 23,800

Commuter Railroads 15 22,526 4

Regional Railroads 30 9,115

Local/Line-Haul Railroads 222 5,060

Switching & Terminal Railroads 130 1,805

Shipper-Owned Railroads 79 2,369

Government-Owned Railroads 36 1,092

Other/Mixed Ownership 8 905 5

TOTAL 555 256,004
 Docket item #A-94-31-IV-D-28. 6

 "1996 Transit Fact Book", American Public Transportation Association. 7

4

Amtrak is the sole large-scale provider of inter-city passenger transport. In

their comments on the NPRM, Amtrak indicated that their fleet includes 315 dieselelectric locomotives, consuming 72 million gallons of diesel fuel annually, plus a

number of all-electric locomotives operating in the Northeast corridor. They offer 6

service to 44 states, extending over 23,000 miles of track. With a few exceptions, most

of the trackage upon which Amtrak trains operate is owned by the freight railroads.

Based on gross revenue, Amtrak is classified as a Class I railroad by the STB.

However, unlike the Class I freight railroads, Amtrak's current operating expenses

exceed its gross revenue. There are also 15 independent commuter rail systems

operating in 12 U.S. cities, consuming 61 million gallons of diesel fuel annually.7

Finally, there are a handful of very small passenger railroads that are primarily

operated for tours. These tourist railroads are included within the Class II and III

railroads.

1.3 Locomotive Remanufacturers and Suppliers

While the original manufacturers provide much of the remanufacturing services

to their customers, there are several smaller entities that also provide remanufacturing

services for locomotive engines. Moreover, some of the Class I and II railroads

remanufacture locomotive engines for their own units and on a contract basis for other

railroads. EPA has been able to identify nine independent remanufacturers that are

small business entities. Due to the necessarily limited demand, most of them find it

advantageous to diversify their operations. Many of them remanufacture marine or

other large diesel engines in addition to locomotive engines. A few apparently

remanufacture locomotives primarily for resale or lease, while six of them

remanufacture engines for operating railroads or industrial customers. Many of these

six remanufacturers also manufacture or remanufacture locomotive engine

components. A few also offer contract maintenance. This may be tied to a locomotive

lease, or may be offered separately to owners of locomotives.

In addition to the above original manufacturers and remanufacturers, EPA has

been able to identify fourteen independent suppliers and remanufacturers of locomotive

engine components for use by railroads or by the independent remanufacturers. All

but two are small business entities who produce and/or remanufacture locomotive

engine components. Again, due to the limited size of the market, many of them

produce and/or remanufacture other locomotive components (in addition to engine

components) or components for marine or large industrial engines). Some of them also

serve as locomotive wreckers and deal in used components.
5

It should be noted that railroad equipment is a broad general industrial category

that includes such components as wheels and axles, traction motors, main

generators/alternators, brakes, air compressors, governors and electronic controls and

a host of other products and services related to railroad cars, as well as locomotive

engines and components. It also includes services such as repainting and conducting

required inspections. Many of the suppliers identified also deal in some of these other

components and services as well as in locomotive engine components. None of these

suppliers list railroad equipment as their primary or secondary business activity. The

primary business codes that they do list range from "plating and polishing" to "turbines

and turbine generators". Most list "industrial machinery and equipment", "internal

combustion engine service" or "necessary repair services" as their primary or secondary

business code.

1.4 Leasing

Locomotives are available for lease from OEMs, remanufacturers, and a small

number of specialized leasing companies formed for that purpose. Leasing practices

appear to be fairly standardized throughout the industry. Although lease contracts can

be tailored on an individual basis, most leases seem to incorporate standard boilerplate

language, terms and conditions. Under a typical lease, the lessee takes on the

responsibility for safety certification and maintenance (parts and scheduled service)

of the locomotive (including the engine), although these could be made a part of the

lease package if desired. The lease duration ranged between 30 days and 5 years, with

the average being 3 years.

As can be seen from the Table 1-2, the use of leasing has increased greatly in

recent years among Class I railroads, with almost two-thirds of the locomotives placed

in service in 1994 being leased. Leasing among Class II and III railroads is not nearly

as widespread, with only about 5 percent of the total number of locomotives being

leased.
 "Railroad Ten Year Trends", Association of American Railroads, 1995. 8

6

Table 1-2

Purchase and Leasing of New Locomotives8

Class I Railroads Only

Year Total New Number Number Percent

Locomotives Purchased Leased Leased

1985 522 430 92 18%

1986 280 173 107 38%

1987 131 110 21 16%

1988 356 320 36 10%

1989 609 523 86 14%

1990 534 417 117 22%

1991 472 273 199 42%

1992 323 213 110 34%

1993 504 379 125 25%

1994 821 288 533 65%
 Values are an approximate estimate by FRA personnel. 9

7

1.5 Locomotive Safety Regulations

Achieving and maintaining the safe operation of commercial (common carrier)

railroads in the U.S. falls under the jurisdiction of the Federal Railroad Administration

(FRA), which is a part of the Department of Transportation. The FRA was created in

1966 to perform a number of disparate functions, including rehabilitating Northeast

Corridor rail passenger service, supporting research and development for rail

transportation, and promoting and enforcing safety regulations throughout the railway

system.

FRA safety regulations apply to railroads on a nationwide basis. These

regulations require a safety inspection of each locomotive used in commercial

operations every 92 days. The inspections are usually performed by the railroad which

owns or leases the locomotive. FRA personnel review the findings of these inspections

and any corrective actions identified and taken. Since each locomotive is required to

be out of revenue service for inspection every 92 days, railroads commonly schedule

their performance of preventive maintenance at these times. It appears likely that

each locomotive is out of service for 12 to 24 hours during each FRA safety inspection

and preventative maintenance period. To limit the time that locomotives are out of 9

service for these safety inspections and preventive maintenance, railroads maintain

suitable facilities distributed across the nation. Thus, it appears that the railroads

have had a long history of compliance with federal regulations, and have developed

strategies to live within the regulations and to minimize any adverse business impacts

that may have resulted.

1.6 Commercial Role of Railroads

Current railroad networks (rail lines) are geographically widespread across the

United States, serving every major city in the country. Approximately one-third of the

freight hauled in the United States is hauled by train. There are few industries or

citizens in the country who are not ultimate consumers of services provided by

American railroad companies. According to statistics compiled by AAR, rail revenue

accounted for 0.5 percent of Gross National Product in 1994. Thus, efficient train

transportation is a vital factor in the strength of the U.S. economy.
 Association of American Railroad. 10

 11 Quoted from May 15, 1997 testimony by Bruce Wilson representing AAR. Docket item

#A-94-31-IV-D-7.

 "Railroad Facts", Association of American Railroads, 1996 edition. 12

8

In order for Class I railroads to operate nationally, they need unhindered rail

access across all state boundaries. If different states regulated locomotives differently,

a railroad could conceivably be forced to change locomotives at state boundaries, and/or

have state-specific locomotive fleets. Currently, facilities for such changes do not exist,

and even if switching areas were available at state boundaries, it would be a costly and

time consuming disruption of interstate commerce. A disruption in the efficient

interstate movement of trains throughout the U.S. could have an impact on the health

and well-being of not only the rail industry, but the entire U.S. economy as well.

Rail transport currently holds about 41% of the market for inter-city freight tonmiles. The remaining segments of this market are accommodated through other modes

of transport, including trucking (27%), river canal/barge (11.5%) and pipeline (18%) of

total ton-miles. Rail is a primary means of transport for many bulk commodities, such

as chemicals (26%), autos (65%), coal (55%) and grain (26%). Being a primary 10

source/mode of transporting these items, the railroad industry normally sets the

industry standard price ($/ton-mile). Rail transport is typically more fuel efficient and

less expensive than other land-based sources of transport. In terms of BTUs of energy

expended per ton-mile of freight hauled, Department of Energy statistics indicate that

rail transport can be as much as seven times more efficient than truck transport. The

AAR has asserted that one double-stack train can carry the equivalent of 280

truckloads of freight.11

Figure 1-1 and Table 1-3 show the long term growth trends for the amount of

freight carried by Class I railroads and the amount of fuel consumed in carrying that

freight. As can be seen from these data, the ton miles of freight carried have more 12

than doubled, while total fuel consumption has remained relatively constant or

decreased slightly. The reason for this is that locomotive manufacturers have made

continual progress in reducing the fuel efficiency of their engines and the electrical

efficiency of their alternators and motors. It is reasonable to project that the growth

in the amount of freight hauled will continue in the future. It is less certain, however,

whether fuel consumption will increase significantly in the near future. (Note: the

analysis of the environmental and economic impacts of this rulemaking assume no

growth in fuel consumption.)
0

500

1000

1500

0

2

4

6

8

10

1955 1960 1965 1970 1975 1980 1985 1990 1995

Ton-Miles Fuel

Figure 1-1 Fuel Consumption and 

Revenue Ton-Miles for Class I Railroads

9

Table 1-3

Annual Fuel Consumption and Revenue Freight

For Class I Railroads

Year Revenue Freight Fuel Consumption

(Million Ton-Miles) (Million Gallons)

1955 623,615 3,384

1960 572,309 3,463

1965 697,878 3,592

1970 764,809 3,545

1975 754,252 3,657

1980 918,958 3,904

1985 876,984 3,110

1990 1,033,969 3,115

1995 1,305,688 3,480
 American Society of Mechanical Engineers, Statement on Surface Transportation of 13

Intercity Freight, May 18,1992.

 U.S. DOE, Transportation Energy Book, Edition 16 (1994), 1996. 14

10

1.7 Environmental Impacts of a Modal Shift

Another important point which required consideration in the regulation of

locomotives is the potential for a modal shift. A modal shift is a change from one form

of transportation, such as trains, to another form, such as trucks. Modal shift can have

negative or positive effects on national and local emissions inventories. Negative

modal shift occurs when there is a shift to a more polluting form of transportation.

Thus, when negative modal shift occurs, the environment suffers.

Information currently available to EPA shows that truck-based freight

movement generates more pollutants per ton-mile of freight hauled than current,

unregulated rail-based forms of freight movement. Estimates quantifying the

difference indicate that locomotives are on the order of three times cleaner than trucks

on an emissions per ton-mile basis. Other studies conducted in the U.S. and Canada 13

have also concluded that freight transported by rail is three times cleaner than that

transported by truck. For example, Department of Energy data show that HD trucks

produce almost 2.5 times the quantity of NOx emissions as do railroads, but only

account for 75 percent as many ton-miles of freight hauled. Thus, any freight 14

normally carried by rail that is instead hauled by trucks would increase the overall

mass of emissions, even at current emissions rates.

Regulations that were overly stringent could raise equipment and/or operating

costs to the point that it might be a wiser economic choice to move current rail freight

by truck. A disruption in interstate commerce resulting from delays caused by

changing locomotives at state boundaries, due to separate state locomotive regulations,

could be costly to railroad companies. These increased costs would be reflected in the

price of hauling freight by rail, and could even eliminate some rail carriers from the

market. In both of these cases, customers would likely switch to the higher-polluting

trucks for the movement of their freight. Overly stringent regulation of the rail

industry or a disruption in interstate rail movement could therefore result in increases

in the emissions inventory, through a negative modal shift. (Note: as is described in

Chapter 7, EPA estimates that this rule will cost railroads about $80 million annually,

which is about one-quarter of one percent of annual freight revenue for U.S. railroads.)
 Essentially all "engine powered" locomotives used in the U.S. employ a diesel engine 15

and the electrical drive system described. The term "diesel-electric" has therefore become

the most common terminology for these locomotives.

11

2.0 Locomotive Background

2.1 Energy Supply Sources for Locomotives

Locomotives may be subdivided into two general groups on the basis of the

source of energy for powering the locomotive: 1) "all-electric" and 2) "engine-powered".

In the "all-electric" group, externally generated electrical energy is supplied to the

locomotive by means of a catenary or some other electrical transfer device. An example

of this type of locomotive is commonly seen moving commuter trains. Power to operate

the locomotive is not generated by an onboard engine. Emission control requirements

for all-electric locomotives would be achieved at the point of electrical power

generation, and thus are not included in this rulemaking.

In the "engine-powered" group of locomotives, fuel (usually diesel in the U.S.)

is carried on the locomotive. The energy contained in the fuel is converted to power by

burning the fuel in the locomotive engine. A small portion of the engine output power

is normally used directly to drive an air compressor to provide brakes for the

locomotive and train. However, the vast majority of the output power from the engine

is converted to electrical energy in an alternator or generator which is directly

connected to the engine. This electrical energy is transmitted to electric motors

(traction motors) connected directly to the drive wheels of the locomotive for

propulsion, as well as to motors which drive the cooling fans, pumps, etc., necessary

for operation of the engine and the locomotive. In the case of passenger locomotives, 15

electrical energy is also supplied to the coaches of the train for heating, air

conditioning, lighting, etc. (i.e., "hotel power"). In some passenger trains, electrical

energy required for the operation of the passenger coaches is supplied by a locomotivemounted auxiliary engine.

2.2 Hotel Power

As noted above, the design of locomotives for use in passenger train service

provides for the locomotive to be operated in either of two distinct modes. In one mode,

the locomotive engine provides only propulsion power for the train. In this mode, the

engine speed changes with changes in power output, resulting in operation similar to

freight locomotives. In the second mode, the locomotive engine supplies electrical

"hotel power" to the passenger cars, in addition to providing propulsion power for the

train. Hotel power provided to the passenger cars can amount to as much as 800 kW

(1070 hp). In contrast to operation in the non-hotel power mode, the engine speed

remains constant with changes occurring in power output when operating in hotel

power mode. Thus, the two modes of operation utilize different speed and load points
12

to generate similar propulsion power. These differences in speed and load points mean

that locomotive engines will have different emissions characteristics when operating

in hotel power mode than when operating in non-hotel power mode.

2.3 Types of Locomotives and Locomotive Design Features

Locomotives generally fall into three broad categories based on their intended

use. Switch locomotives, typically 2000 hp or less, are the least powerful locomotives,

and are used in freight yards to assemble and disassemble trains, or for short hauls of

small trains. Some larger road switchers can be rated as high as 2300 hp. Passenger

locomotives are powered by engines of approximately 3000 hp, and may be equipped

with an auxiliary engine to provide hotel power for the train, although they may also

generate hotel power with the main engine, as discussed above. Freight or line-haul

locomotives are the most powerful locomotives and are used to power freight train

operations over long distances. Older line-haul locomotives are typically powered by

engines of approximately 2000-3000 hp, while newer line-haul locomotives are powered

by engines of approximately 3500-5000 hp. In some cases, older line-haul locomotives

(especially lower powered ones) are used in switch applications. The industry expects

that the next generation of line-haul locomotives will be powered by 6000 hp engines.

Locomotives also vary with respect to size, similar to the variation in

horsepower. Switch locomotives tend to be about 40 to 55 feet long, while line-haul

locomotives are typically 60 to 70 feet long. Locomotive length is roughly correlated

with engine size, and thus the difference in length has become more significant as

locomotive engines have become larger and more powerful. Locomotive length is also

related to the number of axles that a locomotive has. In the past, the typical

locomotive had four axles (two trucks with two axles each). While, there still are a

large number of four-axle locomotives in service, nearly all newly manufactured linehaul locomotives have six axles (two trucks with three axles each). There are two

primary advantages of having more axles on the locomotive. First, with the additional

axles, locomotives can be heavier, without increasing the load on each individual axle

(and thus the load on the rail). Second, six-axle locomotives typically have greater

tractive power at low speeds, which can be critical when climbing steep grades. Fouraxle locomotives, however, are somewhat better for higher speed service. Nevertheless,

it appears that the major railroads are attempting to standardize their fleets by

purchasing six-axle locomotives almost exclusively. This is likely to lead to the future

discontinuation of the practice of converting old line-haul locomotives into switch

locomotives, since these larger six-axle locomotives are probably too long to be practical

in most switch applications.
13

One unique feature of locomotives that makes them different than other,

currently regulated mobile sources is the way that power is transferred from the engine

to the wheels. Most mobile sources utilize mechanical means (i.e., a transmission) to

transfer energy from the engine to the wheels (or other point where the power is

applied). Because there is a mechanical connection between the road vehicle engine

and the wheels, the relationship between engine rotational speed and vehicle speed is

mechanically dictated by the gear ratios in the transmission and final drive (e.g., the

differential and rear axle). This results in engine operation which is very transient in

nature, with respect to changes in both speed and load. In contrast, locomotive engines

are typically connected to an electrical alternator or generator to convert the

mechanical energy to electricity. As noted above, this electricity is then used to power

traction motors which turn the wheels. The effect of this arrangement is that a

locomotive engine can be operated at a desired power output and corresponding engine

speed without being constrained by vehicle speed. The range of possible combinations

of locomotive speed and engine power vary from a locomotive speed approaching zero

with the engine at rated power and speed, to the locomotive at maximum speed and the

engine at idle speed producing no propulsion power. This lack of a direct, mechanical

connection between the engine and the wheels allows the engine to operate in an

essentially steady-state mode, in a number of discrete power settings, or notches, which

are described below.

Another design feature unique to railroad locomotive engines is the design and

operation of the throttle. Power settings for railroad engines (throttle position)

generally involve eight discrete positions, or notches, on the throttle gate, in addition

to idle and the dynamic brake function (which will be considered later). Each throttle

notch position is numerically identified, with notch position one being the lowest power

setting, other than idle, and position eight being maximum power. Because of this

design, each notch on the throttle corresponds to a discrete setting on the fuel delivery

system of the engine. These are the only engine power settings at which the locomotive

can operate. The net effect of this method of control is that the engines can operate at

only eight distinct power levels for propulsion, and at idle and dynamic brake.

Railroads and engine manufacturers have, however, indicated the possibility of either

changing the number of throttle notch positions provided or eliminating throttle

notches entirely in the future.

Dynamic braking is another unique feature of locomotives setting them apart

from other mobile sources. In dynamic braking the traction motors act as generators,

with the generated power being dissipated as heat through an electric resistance grid.

While the engine is not generating motive power (i.e., power to propel the locomotive,

also known as tractive power) in the dynamic brake mode, it is generating power to

operate resistance grid cooling fans. As such, the engine is operating in a power mode

that is different than the power notches or idle settings discussed above. While most

diesel-electric locomotives have a dynamic braking mode, some do not (generally switch

locomotives).
14

Another unique design feature of locomotives is the design of the engine cooling

system and procedures used to control engine coolant temperature. Normal practice

in locomotive design has been to mount the radiator on the top of the locomotive and

not to use a thermostat. Control of coolant temperature is achieved by controlling the

heat rejection rate at the radiator. The rate of heat rejection at the radiator can be

controlled by means such as turning fans on and off or employing a variable speed fan

drive, or by controlling the amount of coolant flow to the radiator (using nonthermostat controls). A related point of difference between road vehicle and locomotive

engine cooling systems is that antifreeze is not generally used in locomotives. Many

factors contribute to this design approach. The very large size of a locomotive engine

causes both a very high degree of difficulty in starting the engine at low temperatures

when the engine has cooled to ambient temperature, and a high probability that

coolant leakage will occur during both warm up and cool down cycles. Because of

problems inherent in starting these engines when allowed to cool to relatively low

ambient temperatures, and the potential for engine damage due to leakage of coolant,

locomotive engines tend not to be shut down for long periods of time, especially during

cold weather. When the engines are shut down, restarts are generally performed

before significant cooling of the engine occurs, to avoid or minimize restart problems

and coolant leakage problems.

The final unique design feature noted here is the manner in which new designs

and design changes are developed. The initial design of any new models/modifications

and production of prototype models are done in much the same manner as is the case

with other mobile sources. Locomotive manufacturers indicated that this process can

be expected to require from 12 to 24 months for significant changes such as those

required to comply with the new Tier 0 standards. Prototype locomotives are typically

sold or leased to the railroads for extended field reliability testing, normally of one to

two years duration. Only after this testing is completed can the new design/design

change be certified and placed into normal production.

2.4 Maintenance

Locomotive maintenance practices also present some unique features. As is the

case with other mobile sources, locomotive maintenance activities can be broken down

into a number of subcategories. Routine servicing consists of providing the fuel, oil,

water, sand (which is applied to the rails for added traction), and other expendables

necessary for day-to-day operation. Scheduled maintenance can be classified as light

(e.g., inspection and cleaning of fuel injectors) or heavy, which can range from repair

or replacement of major engine components (such as power assemblies) to a complete

engine remanufacture. Wherever possible, scheduled maintenance, particularly the

lighter maintenance, is timed to coincide with periodic federally-required safety

inspections, which normally occur at 92-day intervals. Breakdown maintenance, which

may be required to be done in the field, consists of the actions necessary to get a

locomotive back into service. Because of the cost of a breakdown in terms of lost
15

revenue that could result from a stalled train or blocked track, every effort is made to

minimize the need for this type of maintenance. In general, railroads strive to

maintain a high degree of reliability, which results in more rigorous maintenance

practices than would be expected for most other mobile sources. However, the

competitive nature of the business also results in close scrutiny of costs to achieve the

most cost-effective approach to achieving the necessary reliability. This has resulted

in a variety of approaches to providing maintenance.

Maintenance functions were initially the purview of the individual railroads.

Some major railroads with extensive facilities have turned to providing this service for

other railroads, and a few of the smaller railroads also have done the same, in

particular for other small railroads. However, the tendency in recent years has been

toward a diversification of maintenance providers; a number of independent companies

have come into existence to provide many of the necessary, often specialized services

involved (e.g., turbocharger repair or remanufacture). The trend toward outside

maintenance has also been accelerated by the policies of some of the larger railroads

to divest themselves of not only maintenance activities, but ownership of locomotives

as well. The logical culmination of this trend is the "power by the mile" concept,

whereby a railroad can lease a locomotive with all the necessary attendant services for

an agreed-upon rate.

2.5 Replacement Rates

Due to the long total life span of locomotives and their engines, annual

replacement rates of existing locomotives with freshly-manufactured units are very

low. EPA estimated a replacement rate for locomotives and locomotive engines based

on historical data supplied by AAR, and from conversations with manufacturers and

railroad operators. Table 2-1 illustrates the historical replacement rates for

locomotives in the Class I railroad industry. From 1955 through 1995, annual sales

of freshly-manufactured locomotives fluctuated significantly, but have averaged

approximately 500 units over the last ten years. This replacement rate indicates a

fleet turnover time of about 40 years for Class I railroads. Fleet turnover is the time

required for the locomotive fleet to be entirely composed of locomotives that were not

in service as of the base year. Although the percentage of new units in the fleet has

increased significantly since 1994, it is too soon to determine whether this is a general

trend or merely cyclical variation.
 Data are for Class I railroads only. 16

 Includes leased vehicles. 17

16

Table 2-1

Historical Replacement Rates for Locomotives16

Year Total Locomotives in Freshly Manufactured Percent of Fleet which were

Service Locomotives Purchased Freshly Manufactured Units 17

1955 31,395 1,097 3.5%

1960 29,031 389 1.3%

1965 27,780 1,387 5.0%

1970 27,077 1,029 3.8%

1975 27,846 772 2.8%

1980 28,094 1,480 5.3%

1983 25,448 200 0.8%

1984 24,117 436 1.8%

1985 22,548 522 2.3%

1986 20,790 280 1.3%

1987 19,647 131 0.7%

1988 19,364 356 1.8%

1989 19,015 609 3.2%

1990 18,835 530 2.8%

1991 18,344 472 2.6%

1992 18,004 323 1.8%

1993 18,161 504 2.8%

1994 18,505 821 4.4%

1995 18,512 928 5.0%

5 year average 610 3.33%

10 year average 495 2.62%
17

It should be noted that the above data apply to Class I railroads only. Similar

data for Class II and III railroads were not available. Purchasing practices have

historically been for Class I railroads to buy virtually all of the freshly-manufactured

locomotives sold. As the Class I railroads replace their equipment with freshlymanufactured units, the older units are either sold by the Class I railroads to smaller

railroads, are scrapped, or are purchased for remanufacture and ultimate resale (or

leasing) by companies specializing in this work. The industry-wide replacement rate

for locomotives would therefore actually be lower than those indicated for the Class I

railroads only. This would mean that the time required for the total locomotive fleet

to turn over would be longer.

Additionally, independent of cyclic changes in the industry, future locomotive

replacement rates could actually decrease. Locomotive manufacturers are now

producing locomotives that have significantly more horsepower than older locomotives.

Railroads have requested this change so that fewer locomotives are needed to pull a

train. Placing more horsepower on a locomotive chassis increases overall train fuel

efficiency. For example, it would be more fuel-efficient to use two 6000 hp locomotives,

rather than three 4000 hp locomotives, to pull the same weight train, because the

weight of an entire locomotive can be eliminated. Thus, whereas three old locomotives

may be scrapped, only two new locomotives may need to be bought as replacements.

On the other hand, the business outlook for the railroad industry has been

improving in the last few years. As railroads have become increasingly costcompetitive, they are attracting more business. This in turn increases demand for

locomotive power to move the additional freight. Thus, while purchases of new

locomotives may increase in the next few years, these locomotives will likely

supplement, rather than replace, existing locomotives. Moreover, if freight demands

continue to increase, it may become cost-effective to operate locomotives for longer

periods than are estimated here.

2.6 Remanufacturing

Since most locomotive engines are designed to be remanufactured a number of

times, they generally have extremely durable engine blocks and internal parts. Parts

or systems that experience inherently high wear rates (irrespective of design and

materials used) are designed to be easily replaced so as to limit the time that the unit

is out of service for repair or remanufacture. The prime example of parts that are

designed to be readily replaceable on locomotive engines are the power assemblies( i.e.,

the pistons, piston rings, cylinder liners, fuel injectors and controls, fuel injection

pump(s) and controls, and valves). Within the power assemblies, parts such as the

cylinder head in general do not experience high wear rates, and may be reused after

being inspected and requalified. The power assemblies can be remanufactured to bring

them back to as-new condition or they can be upgraded to incorporate the latest design

configuration for that engine. In addition to the power assemblies there are numerous
 Bottom end components, such as crankshafts and bearings, are often remanufactured 18

only during every other remanufacture event. Remanufacture events that do not include

these bottom end components are sometimes referred to as "partial remanufactures"

 In some cases, some components are remanufactured by welding in new metal and 19

remachining the component to the original specifications.

18

other parts or systems that may also be replaced. Engine remanufactures may be 18

performed either by the railroad that owns the locomotive or by the original

manufacturer of the locomotive. Remanufactures are also performed by companies

that specialize in performing this work.

During its forty-plus year total life span, a locomotive engine could be

remanufactured as many as ten times (although this would not be considered the

norm). Locomotive engine remanufacturing events are thus routine, and are usually

part of the scheduled maintenance. It is standard practice for the Class I railroads

within the railroad industry to remanufacture a line-haul locomotive engine every four

to eight years. Typically newer locomotives, which have very high usage rates, are

remanufactured every four years. Older locomotives usually are remanufactured less

frequently because they are used less within each year. Such remanufacturing is

necessary to insure the continued proper functioning of the engine. Remanufacturing

is performed to correct losses in power or fuel economy, and to prevent catastrophic

failures, which may cause a railroad line to be blocked by an immobile train. The

trend toward higher power locomotives is naturally resulting in a trend of fewer

locomotives per train, thereby increasing the likelihood that a train would become

immobilized by the failure of a single locomotive. Road failures are very costly to the

railroads because the importance of timeliness to their customers, and the difficulty

in getting replacement locomotives to the location of the failure.

When a locomotive engine is remanufactured, it receives replacement parts

which are either freshly-manufactured or remanufactured to as-new condition (in

terms of their operation and durability). This includes the emission-related parts 19

which, if not part of the basic engine design, are also generally designed to be

periodically replaced. The replacement parts are also often updated designs, which are

designed to either restore or improve the original performance of the engine in terms

of durability, fuel economy and emissions. Because of a locomotive engine's long life,

a significant overall improvement in the original design of the parts, and therefore of

the engine, is possible over the total life of the unit. Since these improvements in

design usually occur in the power assemblies (i.e., the components where fuel is burned

and where emissions originate), remanufacturing of the engine essentially also makes

the locomotive or locomotive engine a new system in terms of emission performance.

A remanufactured locomotive would therefore be like-new in terms of emissions

generation and control.
19

While Class I locomotives are remanufactured on a relatively frequent and

scheduled basis of 4 to 8 years, Class II and III locomotives may be remanufactured on

a longer schedule or may not be remanufactured at all. The typical service life of a

locomotive (40 years) is often exceeded by small railroads that continue to use older

locomotives. It is important to note that there is no inherent limit on how many times

a locomotive can be remanufactured, or how long it can last. Rather, the service life

of a locomotive or locomotive engine is limited by economics. For example, in cases,

where it is economical to cut out damaged sections of a frame, and weld in new metal,

an old locomotive may be salvaged instead of being scrapped. Remanufacturers can

also replace other major components such as the trucks or traction motors, to allow an

older locomotive to stay in service. However, at some point, most railroads decide that

the improved efficiency of newer technologies justifies the additional cost, and thus

scrap the entire locomotive. Nevertheless, many smaller railroads, especially

switching and terminal railroads, are still using locomotives that were originally

manufactured in the 1940s.
 Chaffin, C., Ullman, T., "Effects of Increased Altitude on Heavy-Duty-Diesel 20

Emissions." SAE Paper 940669, 1994.

20

3.0 Emission Reduction Technology

This chapter provides an overview of emission reduction technology which may

be used on locomotives. The first two sections are brief background discussions of

locomotive pollutants and locomotive operating characteristics. The third section is an

overview of technologies which EPA considered with respect to their potential to reduce

emissions from locomotives. The last section is a discussion of those technologies that

EPA believes will be both available and cost-effective by the time of the locomotive

emissions standards are scheduled to take effect.

3.1 Locomotive Pollutants

The emission constituents of greatest concern from locomotive diesel engines are

oxides of nitrogen (NOx), particulate matter (PM) and smoke. NOx is formed at high

temperatures and pressures associated with combustion of fuel in the engine, when

nitrogen in the air combines with available oxygen in the combustion chamber. PM

generally results from incomplete evaporation and burning of the fuel droplets (and

lubricating oil) in the combustion chamber. Thus, PM emissions are generally

associated with low combustion temperatures, inadequate combustion air in the

vicinity of fuel droplets, and fuel impurities. Since NOx formation is associated with

high combustion temperatures and PM is associated with low combustion

temperatures, many technologies and emission compliance strategies which reduce one

tend to increase the other. Unburned hydrocarbons (HC) and carbon monoxide (CO)

are generally emitted at low levels from properly functioning diesel engines due to the

presence of excess oxygen which allows nearly complete combustion of these

intermediate combustion products. Smoke emissions are typically caused by an

inadequate supply of air for combustion during times of engine acceleration, or by low

combustion temperatures. In general, technologies and compliance strategies that

reduce PM emissions tend to reduce HC, CO and smoke emissions as well, although

to differing degrees.

Ambient conditions also affect emission rates from diesel engines. Temperature

and humidity can both affect NOx emission rates as a result of their effect on

combustion temperatures. NOx emissions are higher at lower ambient humidity

levels, and can be higher at higher ambient temperatures. While not as strong a

relationship, the opposite effect is observed for HC and PM emissions which can be

higher with lower combustion temperatures. Low barometric pressures, which occur

at higher altitudes, can also cause higher smoke and PM emissions with some

reduction in NOx. At high altitudes, where the air is less dense, the engine draws a 20

smaller mass of air, which can result in a lower air/fuel ratio. At such conditions, less

oxygen is available for the combustion process, which results in less complete
 Lizhong, S., et al., "Combustion Process of Diesel Engines at Regions With Different 21

Altitudes," SAE Paper 950857, 1995.

21

combustion of hydrocarbons, as well as increased PM and smoke emissions. This loss

in combustion efficiency also results in lower temperatures which generally means

lower NOx. This potential effect is most prevalent in non-compensated naturallyaspirated engines and less prevalent for turbocharger engines where fuel flow is

adjusted for pressure changes. For naturally aspirated engines, higher altitudes can

actually result in higher peak temperatures due to an increased ignition delay. This

delay is due to a lower density in the cylinder, which leads to less frequent molecular

collisions (between oxygen and fuel), and thus a slower reaction rate. However, the

ignition delay is not observed in engines with sufficient intake air charge.21

Evaporative emissions from diesel engines are insignificant due to the low

volatility of diesel fuel. Diesel engines can have significant crankcase emissions. Since

an engine’s piston rings cannot provide a perfect seal with the cylinder walls, a small

fraction of the products of combustion leak past the piston rings into the crankcase.

This flow of material, known as blowby gases, mixes with the mist of lubricating oil

present in the crankcase and must be vented from the crankcase.

3.2 Locomotive Operating Characteristics

Currently, almost all locomotives used in the U.S. are powered by petroleumfueled diesel engines. As noted in Chapter 2, power produced by the engine is

converted to electricity in an alternator and is subsequently used to move the

locomotive by means of electric motors at the wheels. This mechanical decoupling of

the engine from the drive wheels is significant, in that it allows locomotives to be

designed such that their engines operate in generally steady-state mode in several

discrete load and speed points. It also allows the engine speed for a given power output

to be optimized for fuel economy (and/or emissions) at that power output level. This

is in contrast to most other vehicles, in which the engine and drive wheels are

mechanically connected through a transmission, allowing highly transient operation.

The crankshaft rotational speed of engines (engine speed) used in highway vehicles is

related to the speed of the vehicle, while engine power output at any engine speed can

vary from zero to the maximum possible at that engine speed.

From the perspective of NOx formation in locomotives at a given power output,

it would be desirable to operate the engine at higher rather than lower speed, since

higher speeds are associated with lower combustion temperatures. This operational

approach is undesirable, however, from the perspective of both fuel efficiency and the

formation of PM. As previously described, locomotive engines are designed to operate

only at specific power output levels and engine speeds, and these engine operating

conditions are decoupled from locomotive speed. With the exception of idle and

dynamic brake, locomotive engines used in freight operations tend to be operated at or
 In many cases the swept volume of a single cylinder of a locomotive engine is as large as 22

the total swept volume of all the cylinders of a highway diesel truck engine.

22

close to the maximum power levels achievable at the corresponding engine speed. This

method of operation, while optimizing fuel efficiency and producing relatively low PM

emissions, causes high combustion temperatures and corresponding high NOx

emissions. Changing the basic operating pattern by operating the engine at higher

speeds for given power output levels would tend to reduce combustion temperatures

and thereby NOx formation. The consequences of this approach could, however, be a

deterioration in fuel efficiency, an increase in PM formation, and the need for larger

engines to achieve the same power output, which would tend to further reduce fuel

efficiency.

Finally, because locomotive engines are operated at discrete steady-state

operational points, the design of low emissions control strategies is expected to be

significantly easier than for a engine undergoing more transient operation, such as a

highway truck engine. A locomotive engine will only need to be optimized at about ten

discrete points for low emissions rather than at an infinite set of conditions over the

entire engine torque map. Additionally, at each point the engine operates in an

essentially steady-state condition so that changes in speed and load do not have to be

considered over the entire engine map. Therefore, calibration of parameters such as

aftercooling temperature, fuel injection timing, EGR rate, and others can be better

optimized. Furthermore, a less sophisticated electronic control system is required than

would be necessary for the same emissions control in highway applications.

3.3 Emission Reduction Technologies

This section provides a summary of emission reduction technologies that EPA

considered with respect to their potential applicability to locomotives. The

technologies discussed are broken into the following categories; engine technologies,

exhaust aftertreatment technologies, and changes in fuel (including the use of

alternative fuels) and in lubricating engine oils. Many of these emission reduction

technologies are based on industry experience used to reduce emissions from similar

but smaller engines, used in highway trucks since the 1970's. While many of the 22

emission-control technologies for highway trucks are conceptually applicable to

locomotives and locomotive engines, the design and operation of locomotives and

locomotive engines may reduce the effectiveness of some of these technologies in

locomotive applications. Among the major differences which may potentially impact

the application of these controls to locomotives are the size and design of the engine

(for example, a substantial portion of the current locomotive fleet consists of twostroke engines, whereas most heavy-duty truck engines are four-stroke), the engine

operating speeds (locomotive engines tend to have top speeds of just over 1000 rpm,

whereas highway engine top speeds tend to be well over 2000 rpm), and size

constraints of the vehicle and the infrastructure in which it operates (locomotives
23

must often operate in tunnels and on side-by-side tracks). This last difference is

important when considering available space for charge air cooling and aftertreatment

devices.

It is also important to note that some of the technologies discussed in this

section are still in the research and development phase, and may not be available for

locomotives for many years, if at all. Section 3.4 summarizes which of these

technologies EPA believes will be available in the time frames being considered here.

One final note with respect to the technologies discussed in this section is that, while

each is discussed in isolation, the effective use of some of these technologies can be

optimized through the use of other technologies, and adverse effects of some

technologies can be limited or eliminated through the application of other technologies.

Thus, many of the technologies presented here are more appropriately viewed as

components of larger emission reduction systems or strategies.

3.3.1 Engine Technologies

Fuel Delivery System

Fuel injection improvement is an area that has high potential for emission

reductions from locomotive diesel engines. Emissions can be improved by modifying

fuel injection pressure, fuel spray pattern, injection rate and timing, and by the use of

electronics to control injection rate and timing. While each of these changes, taken

separately, can provide emission reductions, these modifications can be used together

to optimize individual pollutant reductions and minimize fuel economy penalties.

Electronic controls have been instrumental in coordinating these individual

modifications for diesel trucks and have played a significant part in allowing diesel

truck engines to meet very stringent EPA emission standards for NOx, PM, HC, and

smoke, while maintaining fuel economy.

The design of the fuel injector nozzle and the pressure applied to the fuel

determines the fuel spray pattern. The spray pattern from the nozzle needs to be

optimized in conjunction with the configuration of the combustion chamber and

induction swirl to achieve emission reductions. The objectives of this optimization

would be to reduce fuel dropout on the surfaces of the combustion chamber, reduce sac

volume (the volume at the tip of the injector that retains fuel after the injection) to

limit end of injection "dribble", improve fuel atomization and achieve more thorough

mixing with the intake air. These potential changes would reduce HC, PM and smoke

emissions by promoting full combustion and reduce NOx emissions by reducing local

"hot spots" in the combustion chamber.

Modified injection timing is expected to be one of the primary strategies used for

meeting the Tier 0 and Tier 1 emission standards, since optimizing injection timing

and duration can achieve significant NOx emissions reductions at minimal cost.
 Locomotive Exhaust Emission Field Tests - Phase I, Association of American Railroads 23

Report No. R-877, October 1994.

 Locomotive Exhaust Emission Field Tests - Phase II, Association of American Railroads 24

Report No. R-885, March 1995.

24

Injection timing modifications can reduce NOx emissions by lowering peak combustion

pressures and temperatures. Emissions data generated for AAR indicate that

retarding fuel injection by 4 degrees from factory specifications reduces NOx emissions

by over 30 percent on some locomotives. The greatest reductions (31 percent) were 23 24 ,

seen on a two-stroke cycle switch locomotive. All of the line-haul locomotives tested

showed reductions around 25 percent, while the two passenger locomotives tested

showed reductions of 13 to 18 percent. However, due to the lower combustion

temperatures, an accompanying loss in fuel economy was found. The measured

increases in fuel consumption varied from 0.8 to 2.5 percent, with most falling in the

1.0 to 1.3 percent range. EPA expects that some or all of this fuel economy penalty

could be made up through the use of other technologies discussed in this chapter.

However, given the limited lead time available to comply with the Tier 0 emission

standards, it is expected that the primary efforts of the manufacturers and

remanufacturers will initially go toward emissions compliance, and that efforts to

minimize fuel consumption will only take priority after emissions compliance has been

achieved. Thus, it may take a significant amount of time after the effective dates of the

standards for the fuel economy penalty to be erased.

In addition to the fuel economy impact just discussed, increased particulate and

smoke emissions can result from the use of a significant degree of retarded injection

timing, due to the reduced opportunity for the particles to burn. The actual sensitivity

depends strongly on the shape of the NOx vs. PM tradeoff curve for each engine

configuration. This in turn depends on several design variables which can be modified

to minimize the effect. Lower fueling rates is a simple approach to reducing smoke

emissions with retarded injection timing, although it would result in reduced power

output. Such an approach will likely be used only for those locomotive applications

that would not be significantly impacted by a moderate power reduction.

Increasing the overall injection rate can be used to shorten the duration of the

fuel injection event. This shortened duration allows a delay in the initiation of fuel

injection, similar to the effect of retarded injection timing, causing lower peak

combustion temperatures and reduced NOx formation. Increasing the injection rate

tends to reduce the PM and fuel economy penalties of retarded injection timing,

because the termination of fuel injection is not delayed. However, increased injection

rates mean increased injection pressure, and thus increased loading on the components

which power the injector. A redesign of these parts to maintain durability would

probably be necessary.
 "Reduction of Diesel Engine NOx Using Pilot Injection," T. Minami, et al, SAE 950611, 25

1995.

 "Reducing Particulate and NOx Using Multiple Injections and EGR in a D.I. Diesel," D. 26

Pierpont, et al, SAE 950217, 1995.

 "Effects of Injection Pressure and Nozzle Geometry on D.I. Diesel Emissions and 27

Performance," D. Pierpont, R. Reitz, SAE 950604, 1995.

25

Injection rate shaping is a strategy in which the rate of fuel injection is varied

in a controlled manner over the duration of the injection period to reduce emission

formation. In one approach, a small, early burst of fuel (known as pilot injection)

initially enters the combustion chamber, and injection of the majority of the necessary

fuel is slightly delayed until the fuel in the combustion chamber ignites. Injection rate

shaping can reduce NOx formation, because delaying injection of most of the fuel

lowers peak combustion temperatures, thus reducing NOx formation. One study on

a heavy-duty diesel truck engine showed a 25 percent reduction in NOx at 1000 rpm

by using a pilot injection while still improving fuel consumption and reducing PM and

smoke emissions. In another study, a strategy using multiple injections was shown 25

to be capable of offsetting the negative impacts of timing retard on PM emissions by

maximizing the burning of PM late in the combustion event, while maintaining flame

temperatures low enough to avoid NOx formation.26

Increasing injection pressure improves the atomization of the fuel and increases

the mixing of the fuel with the intake air in the combustion chamber. This

combination of reduced droplet size and improved mixing leads to more complete

combustion and decreased formation of PM. Tests on a high-speed diesel engine

showed PM emissions to be reduced by half, with NOx held constant through timing

retard, when injection pressures were raised from 90 to 160 MPa. One drawback of 27

higher injection pressures is the need to strengthen the fuel-injection system and other

components of the engine to deal with higher injection pressures. Without

strengthening of components, a loss in durability could result. The ability to increase

injection pressure, either on existing engines or on future engines derived from present

designs is highly subject to the existing design. On some engines, such as those which

use unit injectors, the magnitude of the changes necessary should not be extreme. On

other engines, those using separate injection pump, fuel distribution lines and

injectors, the necessary redesign would be more substantive.

Another desirable goal for fuel injectors is to limit sac volume. Sac volume is the

small volume of fuel remaining in the tip of the injector at the end of injection. This

fuel may dribble out of the injector at the end of injection and at low loads, causing

increased HC and PM emissions. At high loads this effect is limited during the
26

combustion stroke, because the much higher pressures in the combustion chamber tend

to hold the fuel in the nozzle. However, during the low-pressure exhaust period the

fuel may dribble from the injector and be emitted as HC. Some fuel injection nozzles

have been designed to close the injector spray orifices quickly and completely at the

end of the injection stroke.

At steady-state, smoke emitted by properly operating diesel locomotive engines

is minimal. However, it can occur during periods of engine acceleration, and some

engine designs are more prone to generate smoke at this time than others. Most

typically, the puff of smoke produced during acceleration is caused by "turbo lag,"

which is time required for the turbocharger to reach its appropriate operating speed

after an increase in exhaust flow occurs. As described below, this results in insufficient

air output from the turbocharger for the amount of fuel supplied during accelerations.

Due to pressures from public reaction, locomotive manufacturers have been reducing

visible smoke from the exhaust of properly operating diesel locomotive engines with a

component called a "puff limiter", which limits the rate at which additional fuel is

supplied to the engine during accelerations, and thereby compensates for turbo lag.

The primary disadvantage of a puff limiter is that it causes slower or delayed

acceleration of the engine. This would not be as great a problem for locomotives as for

highway trucks, since locomotive operation is less transient. Costs associated with the

use of a mechanical puff limiter are relatively low. Electronically controlled puff

limiters are more expensive, but should be more effective and less susceptible to

tampering than mechanical designs. As an option, a turbocharger capable of increased

air flows can be used to ensure that enough air is available to avoid reaching the smoke

limit during accelerations. If such a turbocharger were used, a wastegate could be

used during steady-state operation to prevent overcharging of the cylinder. The

wastegate would essentially route some of the exhaust away from the turbine.

Charge Air Compression and Cooling

The typical goal in engine design is to achieve the desired power output and

reliability, while constraining weight and size, at the lowest possible cost. A common

method to achieve an increase in power output without an increase in engine size

(displacement) and weight, is the use of charge air compression (e.g., turbocharging).

A turbocharger uses the energy of the hot exhaust gases to turn a turbine, which in

turn is attached to an air compressor in the intake air stream. This approach increases

the mass of air entering the engine's combustion chambers, which allows more fuel to

be used, which increases power output. However, charge air compression also heats

the intake air, which increases the formation of NOx. Durability also becomes a

significant concern due to elevated temperatures and loads. These problems can be

resolved through the use of charge air aftercooling, which will be discussed shortly.

Charge air compression can be accomplished in various ways, but the dominant

method used for diesel engines is turbocharging. The charge air compression process
 "Optimization of Heavy-Duty Diesel Engine Transient Emissions by Advanced Control 28

of a Variable Geometry Turbocharger," A. Pilley, et al, SAE 890395, 1989.

 "Performance and Emissions Trade-Offs for a HSDI Diesel Engine - An Optimization 29

Study," Z. Bazari, B. French, SAE 930592, 1993.

27

must be closely linked to the engine fuel control system to ensure that the two work

together properly, thus ensuring that fuel consumption and emissions formation are

minimized, including preventing smoke generation due to turbo lag. The magnitude

of this problem varies between engines produced by different locomotive

manufacturers. As noted above, one method commonly used to address this problem

is to slowly increase the fueling rate following a change in throttle position. Other

methods to address this problem include the use of a variable geometry turbocharger

(VGT), multiple turbochargers, electronic matching of the turbocharger and fuel

injection, or mechanical drive of the compressor (i.e., the use of a supercharger rather

than a turbocharger). A variable geometry turbocharger can significantly reduce the

problems of turbocharger lag. By changing the geometry of the gas flow passages in

the turbine, the response time of the turbocharger can be improved. For instance, one

design uses a sliding mechanism to block part of the exhaust flow passage in the

turbine. Because the same amount of exhaust has to pass through a smaller flow

passage, the exhaust gasses must travel faster which, in turn, causes the turbine to

spin faster. VGTs require slightly more space, are more costly than a conventional

turbocharger. Over a section of the on-highway transient Federal Test Procedure,

particulate reductions of up to 34 percent have been achieved on a heavy-duty diesel

truck engine through the use of a VGT, without increasing NOx emissions.28

The heating that is caused by compression of the charge air increases NOx

emissions. This can be minimized by cooling the charge air after compression. Charge

air cooling also increases the mass of air available for combustion, and may reduce

durability problems associated with high combustion temperatures. While the lower

temperatures can cause some increase in PM emissions, if the decrease in combustion

temperatures is small enough, PM emissions may be unaffected or may even decrease

(due to the additional oxygen available for combustion). One study showed that charge

air cooling resulted in decreased smoke, HC, NOx, and PM emissions and fuel

consumption, especially at high loads where most NOx is created.29

There are two basic types of charge air coolers (or aftercoolers): air-to-liquid

units and air-to-air units. Historically, in air-to-liquid systems, engine coolant has

been used as the cooling medium both for highway trucks and locomotives. The

amount of cooling with an engine coolant system is limited by the relatively high

temperature of the coolant. Air-to-air aftercoolers use a stream of outside air flowing

through the device to cool the charge air. By using ambient air, an air-to-air
 The term ram air is used to denote the air forced through an aftercooler and/or a 30

radiator by the motion of the vehicle.

28

aftercooler can cool the compressed intake air to a temperature approaching that of the

ambient air, and thus can be more effective in lowering the temperature of the

compressed charge air and thus reducing NOx levels.

Air-to-air aftercoolers are widely used at present in diesel engines for highway

truck operations, and the potential exists for their use on locomotives as well.

However, air-to-air aftercoolers generally rely heavily on ram air to get cooling air 30

into the aftercooler system. While this is not a problem for trucks operating at

highway speeds and which have the engine, the aftercooler and the engine radiator

mounted in the front of the vehicle, it could be more problematic for locomotives. For

multi-locomotive trains, there exists no comparable direct frontal area for introduction

of ram air into the aftercooler systems of locomotive engines. Air scoops or air dams

could be used to divert air into an aftercooler system. Any air scoops or air dams

installed on a locomotive would need to be bidirectional, facing the "front" and the

"rear" of the locomotive. This is because locomotives can and do operate in both

directions. The size and shape of any air scoop system is also limited by the space

constraints on the locomotive itself, and space constraints due to the infrastructure in

which the locomotive must operate. In addition, locomotives often operate at

maximum engine power and low locomotive speed for extended periods of time, which

means that little air would be introduced to an air-to-air aftercooler system due to ram

air. Blower fans could be incorporated to insure that a sufficient quantity of air is

introduced into the aftercooler system. It is possible that the cooling fans already used

on locomotives for engine cooling or the fans used to dissipate the heat generated

during dynamic brake could be made to serve a dual purpose.

Air-to-liquid aftercoolers (e.g., radiators) are the type currently in general use

for locomotive applications, in one of two configurations. As previously noted, one type

uses engine coolant to lower engine intake air temperature to a level near the

operating temperature of the engine coolant. This limits the amount of cooling that

can be accomplished due to relatively high engine coolant temperatures. However, as

a result, the temperature of the engine intake air, and thus the level of emission

control, is somewhat self-regulating and remains relatively constant (near the engine

coolant temperature) over a wide range of ambient temperatures. The overall

effectiveness of this approach might be improved by increasing the overall size of the

heat exchanger area, the air-to-surface ratio in the system, or by using a cooling fluid

with a higher heat capacity.

The second type of air-to-liquid charge air cooling system is an aftercooler using

a coolant system separate from the engine coolant system. Such a system, also known

as split cooling, has been used on some recent production locomotives. Split cooling can

cool engine intake air temperatures almost as effectively as an air-to-air aftercooler.
29

However, coolant temperatures are tied to ambient temperatures, necessitating

appropriate controls to reduce seasonal variations in intake air temperature. The use

of antifreeze would probably be necessary to prevent freezing of the aftercooler system

under low ambient conditions (which represents a departure from current railroad

practice of not using antifreeze). Introducing a separate liquid system for aftercooling

could also be more complex than either of the other above-mentioned systems. Space

constraints on a locomotive would also need to be considered.

A third type of potential air-to-liquid system is a combination of the two previous

types with charge air being routed only through the separate coolant system

components during high ambient temperature operations, and through both the

separate coolant and engine coolant system components during low ambient

temperatures to prevent overcooling. This more complex approach to control of

overcooling, while theoretically possible, is expected to be a more costly approach than

could be achieved by other means.

Combustion Chamber Modifications

Diesel truck engine manufacturers have achieved significant emission

reductions through changes to the engine's combustion chamber. Combustion chamber

design modifications can also reasonably be expected to provide emission reductions

for locomotive engines. Redesign of the shape of the combustion chamber and the

location of the fuel injector can optimize the motion of the air and the injected fuel with

respect to emission control. Reductions in both NOx and PM are expected to be

achieved with some combustion chamber configurations currently under development.

Compression ratio is another engine design parameter that impacts emission

control. In general, lower compression ratios cause a reduction in NOx emissions and

decreased fuel economy, but also cause an increase in PM emissions, while higher

compression ratios tend to have the opposite effects. Lower compression ratios also

play a part in lowering the loads imposed on the components of the engine and, as a

result, may contribute to the durability of the units. Compression ratios employed in

locomotive engines are typically somewhat lower than those used in truck engines,

although some recent designs have gone to higher compression ratios, possibly for

lower PM emissions, but more likely for fuel economy reasons. 

Increasing turbulence in the combustion chamber either as a result of

turbulence in the intake air, by chamber design, or a combination of both (i.e., inducing

"swirl") can reduce PM emissions from diesel engines by improving the mixing of air

and fuel in the combustion chamber. Historically, swirl has been induced in truck

engines by intake air routing and by chamber design. Truck manufacturers are,

however, increasingly using "reentrant" piston designs, in which a lip is formed at the

top of the piston bowl into which the air is compressed, thereby causing controlled

swirl. Manufacturers are investigating the applicability of this chamber design to
 "Cost Estimates for Meeting the Proposed Locomotive Emission Standards," Engine, 31

Fuel, and Emissions Engineering, Inc., September, 1997

30

locomotive engines. A change in materials or a change in the shape of the chamber

may be helpful in adapting this strategy to locomotive use, and the technology holds

promise for application on locomotives.

Combustion chamber design can be further optimized to decrease PM emissions.

The location of the top piston ring relative to the top of the piston has undergone

significant investigation in truck engines. The location of piston rings has been

modified to reduce the crevice volume, i.e, the space between the top ring and the top

of the piston, while retaining the durability and structural integrity of the piston and

piston ring assembly. These changes result in reduced HC and PM emissions. Raising

the top piston ring requires modified routing of the engine coolant around the cylinder

to prevent overheating of the raised ring. Applicability of this approach to locomotive

engines is under investigation.

Some designers are investigating the possibility of adding ceramic materials to

the surfaces of the combustion chamber. Ceramic coatings may provide effective

insulation, allowing more energy to be retained in the products of combustion and

thereby increasing fuel efficiency. Retaining more energy in the combustion chamber

increases peak combustion temperatures, resulting in decreased PM emissions and

increased NOx emissions. When combined with other modifications such as modified

injection timing, rate shaping and reduced fueling rate, the use of ceramics may result

in a reduction in PM without a corresponding increase in NOx emissions or fuel

consumption.

Electronic Controls

Various electronic control systems have been developed and are already in use

on some newer locomotives. EPA expects that the electronic control systems currently

in use will continue to be improved. Use of electronic controls enables designers to

implement much more precise control of the fuel injection system, such as injection

rate shaping and variable injection timing, than is possible with a mechanical system.

This allows designers to achieve improved emission control with little or no fuel

consumption penalty. The contractor cost report estimates that electronic controls

would result in a two percent fuel consumption savings in locomotives, which could

offset the fuel consumption penalty associated with retarded injection timing. Also, 31

electronic controls are necessary for implementation of advanced concepts such as rate

shaping.
 "Combined Effects of EGR and Supercharging on Diesel Combustion and Emissions," 32

N. Uchida, et al, SAE 930601, 1993.

31

Reduced Oil Consumption

Manufacturers have evaluated, and continue to evaluate means for reducing the

consumption of lubricating ("lube") oil, which would result in a lower lube oil

contribution to PM emissions. The trade-off which is made in reducing oil consumption

is with engine durability. Since durability is a very high priority in locomotive

engines, EPA expects that manufacturers will continue to strive to reduce oil

consumption, but not at the expense of durability. Any significant benefits in PM

control which may be attributable to reduced oil consumption will probably be more of

a longer-term undertaking. This effort may also lead to the eventual disappearance

of two-stroke cycle engines from locomotive use, since four-stroke engines generally are

able to achieve better oil control, resulting in much less oil as a PM constituent. 

Intake Air Dilution

Displacing some of an engine's intake air with inert materials is another NOx

reduction strategy. The inert material lowers combustion temperatures by diluting the

mixture in the cylinder and absorbing heat from the burning fuel. The reduced

temperatures caused by intake air dilution, with or without aftercooling of the intake

air, result in lower levels of NOx emissions. Two identifiable methods are exhaust gas

recirculation (EGR) and water injection.

Exhaust gas recirculation uses gases from the exhaust stream to dilute the

combustion mixture. The recirculated exhaust gases absorb a portion of the energy

released during combustion of the fuel, decreasing the peak combustion temperature

and reducing NOx formation and engine power. EGR in gasoline-fueled engines is

most often accomplished by routing a portion of the exhaust stream from the exhaust

system into the intake air. As an alternative, manufacturers may use "internal" EGR

by coordinating the timing of the intake and exhaust valve events so that a portion of

the exhaust gas from the previous combustion event is retained in, or drawn back into,

the combustion chamber. This approach is less costly in terms of hardware

requirements, but also less effective than external EGR. One study on a single

cylinder engine showed that when combined with turbocharging and charge air cooling,

20 percent EGR can reduce NOx by approximately 50 percent without penalties in

smoke or HC emissions.32

While EGR has been successfully applied in gasoline engines, there are some

potential drawbacks in the application of EGR to the diesel engines used in

locomotives. The abrasiveness of the particulate matter in the exhaust stream may

cause accelerated wear in the engine and turbocharger, and PM can also find its way

into the engine lubricating oil. Also, the particulate matter can form deposits on
 "NOx Reduction Strategies for DI Diesel Engines,” Herzog, P., et al, SAE 920470, 1992. 33

 "Combined Effects of EGR and Supercharging on Diesel Combustion and Emissions," 34

Uchida, N., et al, SAE 930601, 1993.

 "New EGR Technology Retains HD Diesel Economy with 21st Century Emissions," 35

Baert, R., et al, SAE 960848, 1996.

32

components of the engine intake system, decreasing the heat transfer capability of the

aftercooler, and potentially decreasing the effectiveness of the turbocharger if

introduced upstream of this unit. In addition, by reducing combustion temperatures

and decreasing the amount of air available for combustion, EGR may cause incomplete

combustion, resulting in increased HC, CO, PM and smoke emissions.

There are several methods of controlling the PM emissions attributed to EGR.

One method is to cool the exhaust gas recirculated to the intake manifold. With EGR

cooling, a much higher amount of exhaust gas can be added to the intake charge. A

small NOx penalty due to increased ignition delay was observed on a truck engine at

light loads, but at high loads, some additional NOx reduction resulted from EGR

cooling. Another method to offset the negative impacts of EGR on PM is through the 33

use of higher intake air boost pressures. By turbocharging the intake air, exhaust gas

can be added to the charge without reducing the supply of fresh air into the cylinder.34

Because locomotive engines generally operate at a discrete number of steady-state

conditions in use, it should be much simpler to optimize the use of EGR than for a

highway application which is typically characterized by highly transient operation.

Particularly through the use of electronics, EGR rates can be optimized with the air

and fueling strategy independently for each notch. Concerns associated with transient

operation, such as those related to the problem excess EGR during decelerations, are

minimal.

One study considered a technology package designed to solve the problems of

minimizing the amount of intake charge displaced by exhaust gas and of fouling the

turbocharger and intercooler. This technology package uses a variable geometry 35

turbocharger (VGT), an EGR control valve, and a venturi mixer to introduce the

recirculated gas into the inlet stream after the intake air is compressed and cooled. In

addition to compressing the intake air, the VGT is used to build up pressure in the

exhaust stream. Once the pressure is high enough, the EGR control valve is opened

and the recirculated gas is mixed in to the high pressure inlet stream. Although the

recirculated gas is cooled, this cooling is kept minimal to prevent both fouling in the

cooler (due to condensation) and a large pressure drop across the cooler. 
 Fleet Owner, “Hardware Report: What’s new in... Bypass Filtration,” magazine article, 36

January 1997.

 "The EGR System for Diesel Engine Using a Low Voltage Soot Removal Device," 37

Yoshikawa, H., et al, SAE 930369, 1993.

 "Reducing Diesel Particulate and NOx Emissions via Filtration and Particle-Free 38

Exhaust Gas Recirculation," Khalil, N., et al, SAE 950736, 1995.

 "An Optimization Study on the Control of NOx and Particulate Emissions from Diesel 39

Engines," Larsen, C., et al, SAE 960473, 1996.

 "An Elegant Solution for Vehicular Diesel's Emission and Economy - Hybrid EGR 40

System," Akiyama, M., et al, SAE 960842, 1996.

33

Several bypass oil filtration designs exist for diesel truck engines which will

filter the smaller particles (those missed by the primary filtration system) out of engine

oil. With bypass filtration, a portion of the oil is run through a secondary unit which 36

results in better filtration of the oil. This type of filtration system could be used to

minimize negative effects of PM in the oil that is associated with high levels of EGR.

At least one of design claims efficiencies of up to 99% in capturing 1-micron particles.

Another design is capable of removing water, as well as particles less than 1 micron

in size. To accelerate vaporization of impurities and to maintain oil viscosity, a heated

diffuser plate is used in a third design. A low-voltage soot removal device that reduces

the PM in the recirculated gas by 50 to 84 percent has been developed. Engine wear

was shown to be greatly reduced on a test truck engine as a result of this device.

Testing was performed at 30 percent EGR. Another strategy for reducing particles 37

in EGR is to recirculate the exhaust gas after it has passed through a particulate trap.

Traps typically can remove more than 90 percent of particulate matter, whereas some

designs have achieved a 99 percent particle collection efficiency. 38,39

A hybrid EGR system is also being studied as a potential solution to durability

problems associated with recirculated diesel exhaust. In this system, a small gasoline 40

engine is used to drive the supercharger for a larger diesel engine. A portion or all of

the gasoline engine exhaust can then be fed into the intake stream of the diesel engine.

Because of the lack of sulfuric acid and the very low carbon content in the gasoline

filtration, a portion of the oil is run through a secondary unit, engine exhaust, the

problems of wear and erosion of parts in the diesel engine associated with EGR are

alleviated. Another bonus of this system is that the boost pressure is independent of

the load and speed of the diesel engine. Therefore, there is more flexibility in

optimizing the emissions and fuel consumption of the diesel engine. The study

referenced above showed that the hybrid EGR system had about the same fuel

consumption as a conventional EGR engine, but with a larger NOx decrease. However,

such systems are far from being ready for practical use.
 "Reduction of Smoke and NOx by Strong Turbulence Generated During the 41

Combustion Process in D.I. Diesel Engines," SAE 920467, 1992.

34

Water injection is a second form of intake air dilution. Water injection works

like EGR, absorbing heat to vaporize the water and heat the resulting steam, which

lowers peak combustion temperatures and decreases NOx formation. Since the water

would be introduced as a liquid, only a very small portion of the charge air volume

would be displaced, and the effects on engine power would not be large. Testing on a

diesel engine has shown a 40 percent reduction in NOx with a water-fuel ratio of 0.5

with only a slight increase in smoke emissions. However, water injection imposes 41

significant technical and regulatory problems. First, it can lead to increases in PM and

smoke emissions. Second, the water can cause corrosion of engine components, and the

use of water with dissolved impurities (such as calcium carbonate) could lead to

deposits in the water injection system and in the engine. Purified water would be

needed to avoid such deposits. Also, insulation in the water tank and injection system

or additives to the water would be necessary to prevent the water from freezing in

winter. Finally, water injection would require the engine operator to refill the water

reservoir periodically.

Emission control systems that require an operator to physically perform

alterations or additions to a system may not be effective in the field in achieving

emission benefits, especially if not performing those acts would not seriously decrease

engine performance. Because the engine could potentially function without the water

as well as it would with it, there may be no incentive for the operator to comply with

the requirement. Because of the large amounts of water that would be needed, water

injection for a locomotive application could possibly require the addition of a "water

car" behind the locomotive, adding additional weight to the train. Additionally,

railroad companies may have to develop infrastructure in the form of purified water

storage tanks in train yards and along track, similar in concept to the water towers

used for old steam powered locomotives.

Turbo-Compounding

Turbo-compounding is the addition of a second power recovery turbine in series

with the turbine of the turbocharger. This second turbine captures and converts some

of the remaining energy in the exhaust gases to useful work. This useful work is

transmitted to the crankshaft by a gear train, thereby increasing overall engine

efficiency. By reducing fuel consumption, addition of such a waste heat turbine would

lead to a corresponding reduction in overall exhaust emissions on a g/bhp-hr basis. A

waste heat turbine may require the application of ceramic engine designs. The

durability of such systems has yet to be addressed for locomotive applications, although

they were successfully used in piston-driven aircraft applications for a number of years.
35

Also, the addition of the extra turbine could pose packaging problems for current

locomotives. Costs associated with this approach are expected to be high for the

amount of emission reductions achieved. If utilized, EPA expects that it would only

occur in the long term.

Closed Crankcase

Preventing the discharge to the atmosphere of the mixture of blowby gases and

lubricating oil mist in the crankcase is referred to as “closing the crankcase” and in the

case of gasoline-fueled engines has been achieved by routing the blowby gases to the

engine air intake. EPA regulations applicable to highway diesel engines require the

use of closed crankcase systems only on naturally aspirated diesel-fueled engines. EPA

exempted diesel-fueled truck engines with charge air compression because of the

possibility of blowby gases decreasing the effectiveness of turbochargers and

aftercoolers. For highway diesel engines equipped with charge air compression, closing

the crankcase would depend on the development of designs that protect turbochargers

and aftercoolers from damage. On some turbocharged locomotive engines, crankcase

closure is effectively achieved by routing the blowby gases into the exhaust stream

after the turbocharger. Since exhaust HC emission measurements for such systems

include HC emissions in the blowby gases, this approach can be considered as meeting

the intent of a closed crankcase. There appear to be no negative effects on fuel

efficiency or engine performance.

3.3.2 Exhaust Aftertreatment Technologies

In order to meet EPA's NOx and PM standards for on-highway heavy-duty diesel

engines, manufacturers have investigated exhaust aftertreatment as a supplement to

engine-based emission control technologies. This technology is theoretically

transferrable to diesel engines used in locomotives, giving consideration to space

availability on the locomotive and the durability of the technology. In general,

incorporating exhaust aftertreatment is more expensive than modifying engine

designs, but aftertreatment can result in additional emission reductions beyond those

achievable through changes in engine design. Aftertreatment may also lessen the

trade-offs involved in controlling both NOx and PM emissions while retaining fuel

efficiency. For example, the use of aftertreatment devices to control PM emissions

would provide engine designers more flexibility to focus on reducing NOx formation in

the engine. In general, development efforts for aftertreatment devices for locomotive

applications are behind those efforts associated with improving engine-out

performance.

Work is being done to develop reduction catalysts that would specifically reduce

NOx emissions. These devices, known as selective catalytic reduction (SCR) systems

require an adequate concentration of substances called reductants or reducing agents

that react readily with NOx. Reduction catalyst technology is currently in the
 "Catalytic NOx Reduction in Net Oxidizing Exhaust Gas," W. Held, SAE 900496, 1990. 42

 Docket items A-94-31-IV-D-8 and A-94-31-IV-E-3. 43

36

development stage for mobile diesel applications, although such catalysts have been

used successfully in industrial applications. The goal of these catalysts is to lower NOx

emissions in the presence of the oxygen-rich exhaust gases characteristic of diesel

engines. These types of catalysts are therefore sometimes called lean-NOx catalysts.

While finding space on the locomotive to install an aftertreatment device is a

concern, the primary challenge in the use of catalyst technology to control NOx from

locomotive diesel engines is the need to provide adequate supply of a reducing agent

in the exhaust stream. Two means of achieving this are the supplemental injection of

reducing agents and a diesel exhaust-NOx catalyst which utilizes the exhaust

hydrocarbons already present as a reducing agent. Both types of catalyst systems

typically make use of zeolite molecular sieves, selectively trapping the molecules of

reactant materials. Zeolite sieves are substances with a crystalline structure capable

of trapping molecules of certain sizes while allowing others to pass through. 

The reducing agents most typically considered for injection into the exhaust

stream are urea, ammonia and diesel fuel. Urea and ammonia are effective reducing

agents in industrial applications, achieving high NOx reduction efficiencies in steadystate operation. Developing such catalysts for highway diesel applications has been 42

difficult due to the transient operating characteristics of highway vehicles, which

require these systems to be effective under frequently varying load conditions. This

would be less of a consideration in designing for locomotive operation, which is more

like a series of steady-state modes. One SCR supplier has claimed that recent

advances in the predictive modeling of emissions at various operating modes and the

development of corresponding reductant metering strategies has resulted in NOx

reductions of 90%, with concurrent PM reductions of 50% and HC reductions of 85%.43

Relying on urea or ammonia for effective catalyst operation also raises

regulatory concerns. These chemicals are consumed to achieve NOx reduction, so

vehicle operators would need to maintain an adequate supply on their vehicles.

Operators may have no practical incentive for maintaining an adequate supply of the

required reducing agents unless the control systems were designed such that running

out of the reducing agent would cause vehicle performance to be seriously degraded.

Without such a safeguard there would be little incentive to keep an adequate supply

of reducing agent in a locomotive, since the lack of reductant would otherwise be

transparent to the operator. One must not only consider the initial cost of the hardware

and the ongoing cost of the reducing agent, but also the cost of the reducing agent

refilling infrastructure that must be developed to support locomotives utilizing such

technology.
 "Catalytic Reduction of NOx and Diesel Exhaust," S. Sumiya, et al, SAE 920853, 1992. 44

 "Catalytic Reduction of NOx in Actual Diesel Engine Exhaust," M. Konno, et al, SAE 45

920091, 1992.

37

The use of ammonia and urea as reductants on locomotives poses another

potential problem because exhaust gas temperatures from locomotive engines in most

throttle notches may be lower than the minimum required for proper operation of the

catalyst. Usage could be limited to high loads where NOx is formed, or another

suggested approach to solving this problem involves the injection of additional diesel

fuel into the exhaust gases for combustion, thereby increasing exhaust gas

temperatures to levels sufficient for the reduction reactions to occur. In such a design,

a small amount of diesel fuel is sprayed into the exhaust stream upstream of the

catalytic converter in metered amounts, corresponding to engine NOx output levels.

NOx reduction efficiencies of 30 to 80 percent have been reported in steady-state

experimental systems. The reported NOx reduction efficiency of 80 percent 44 45 ,

corresponded with a 5 percent loss in fuel economy. Fuel used for this purpose would

obviously have negative effects on fuel efficiency, increasing operating costs and

possibly raising HC, CO, PM and smoke emissions. (Fuel efficiency decreases, because

fuel that is injected for NOx reduction does not produce power output from the engine.)

Using unburned diesel fuel as the injected reducing agent would, however, tend to

resolve the concern over operator participation because the fuel would always be

available on a locomotive.

Chemical aftertreatment with cyanuric acid is also being investigated as a

method to reduce NOx emissions. As exhaust gas passes over cyanuric acid pellets, the

pellets give off cyanic acid gas (HCNO), which reacts with NOx to form nitrogen,

carbon dioxide and water. California has identified this as a "best available

technology" for stationary sources which have largely steady-state operation with

relatively gradual changes in output power levels. This type of operation is similar in

some ways to that for locomotive engines.

Aftertreatment devices such as oxidation catalysts may be considered for use on

locomotives to reduce PM emissions. PM emissions from diesel engines are composed

of carbonaceous particles, a soluble organic fraction, sulfates and adsorbed water.

Oxidation catalysts tend to reduce the soluble organic fraction and have little effect on

the carbonaceous portion of PM in diesel exhaust, since soluble organic fractions arise

from unburned fuel and lubricating oil. This limits the reduction in PM emissions that

an oxidation catalyst can achieve. Furthermore, oxidation catalysts convert a portion

of the sulfur dioxide present in the exhaust stream to sulfate PM. Because the

increased sulfate PM can offset the reduction in the soluble organic fraction, an

oxidation catalyst may not be as effective as expected in reducing total PM emissions,
 "Effects of Sulfate Adsorption on Performance of Diesel Oxidation Catalysts," 46

N. Harayama, et al, SAE 920852, 1992.

 "Technical Feasibility of Reducing NO and Particulate Emissions From Heavy-Duty 47

x

Engines," Acurex Environmental Corporation, April 30, 1993, p. 3-38.

38

especially when high sulfur fuel is used. A major goal in the development of oxidation

catalysts for diesel engines is therefore to increase oxidation of the soluble organic

fraction while having little if any effect on the oxides of sulfur present. Optimized

designs (addressing operating temperature, exhaust gas flow path, selection of catalyst

materials, and other parameters) appear capable of reducing total PM emissions from

diesel engines using low sulfur fuel by 20 to 30 percent. . Actual reductions are very 46 47 ,

dependent on the magnitude of the soluble organic fraction (compared to the

carbonaceous portion) from engine-out exhaust. The mandatory use of low sulfur diesel

fuel in locomotives would have to be considered if catalyst use became widespread.

The durability of diesel engine catalytic converters is unproven for large diesel

engines such as are used to power locomotives. However, experience gained from light

and medium heavy-duty truck and urban bus applications supports the expectation

that oxidation catalysts with sufficient durability can eventually be developed for

larger, more durable engines used in locomotives.

Another type of aftertreatment is the particulate trap oxidizer (trap) which

filters particulate matter from the exhaust stream with subsequent oxidation of the

filtered particulate. The basic element of a trap system is a structural shell containing

the filter material. Filters currently under development for truck and bus engines are

either ceramic wall-flow monolith filters or filter tubes covered with multiple layers of

a yarn-like ceramic material. The filter material contains many small holes that allow

the exhaust gases to pass through while collecting the particulate from the raw

exhaust.

The particulate matter collected by the filter eventually needs to be removed.

It is generally burned off in a process called regeneration. Two general approaches for

regeneration of the trap have been investigated. One approach employed is the use of

catalytic material on the filter which causes regeneration once a predetermined trap

loading is reached. The other approach includes a system for heating the filter to

oxidize the particulate, a microprocessor for controlling filter regeneration and, in some

systems, a supplemental air supply system. 
 "National Fuel Survey, Diesel Fuel, Summer 1992," and "National Fuel Survey, Diesel 48

Fuel, Winter 1992," Motor Vehicle Manufacturers Association, 1992.

 "Diesel Fuel Property Effects on Exhaust Emissions from a Heavy-Duty Diesel Engine 49

That Meets 1994 Emission Requirements", McCarthy, et al, SAE 922267, 1992.

 "Effects of Fuel Aromatics, Cetane Number and Cetane Improver on Emissions from a 50

1991 Prototype Heavy-Duty Diesel Engine," T.L. Ullman, et al, SAE 902171, 1990.

 51 "Cost-Effectiveness of Diesel Fuel Modifications for Particulate Control," M.C. Ingham

and R.B. Warden, Chevron, SAE 870556, 1987.

39

3.3.3 Changes in Fuel and Lubricating Oil

Diesel fuel

There are some changes that could be made to the composition of diesel fuel to

reduce emissions, at the expense of requiring the railroads to use new and more costly

fuels. Also, the possible changes to diesel fuel tend to be interdependent. For example,

an increase in a fuel's cetane number is usually associated with a decrease in aromatic

content and an increase in volatility. It is therefore difficult in some cases to determine

separately the effects of changing individual parameters.

The cetane rating is a measure of the tendency of a fuel to autoignite. The effect

of raising the cetane rating of diesel fuel is that it increases autoignition of the fuel in

the combustion chamber, generally improving combustion. A fuel's cetane rating can

be increased either with a fuel additive that enhances autoignition, or through

modified processing of diesel fuel at the refinery. Currently, the nationwide average

cetane number is approximately 44 for highway diesel fuels . A typical gallon of diesel 48

fuel also consists of 20 to 45 percent aromatic hydrocarbons by volume. Decreasing the

aromatic content of diesel fuel, which is closely correlated with increased cetane rating,

seems to have a greater potential for decreasing both PM and NOx emissions than

changing fuel composition in other ways. In one study reducing the aromatic content

of diesel fuel used in truck engines from 40 to 20 percent , and increasing the cetane

number from 44 to 53 resulted in a 4 percent reduction in NOx and a 7 percent

reduction in PM . In another study, a 10 percent reduction in PM emissions was 49

reported as a result of reducing the aromatic content from 40 to 10 percent. 50

Sulfur occurs naturally in crude oil and, unless removed, also occurs in refined

diesel fuel. Two basic emission problems are associated with sulfur in diesel fuel.

First, the sulfur in the fuel reacts to form oxides of sulfur (SOx), including about 3

percent of the fuel sulfur that is directly emitted as particulate in the form of sulfuric

acid. SOx can also react in the atmosphere to form sulfate PM. Second, for vehicles 51

equipped with particulate traps or catalysts, fuel sulfur can cause deterioration in the

substrate materials, decreasing the effectiveness and durability of the trap or catalyst.
 "Description of Diesel Emissions by Individual Fuel Properties," Noboru Miyamoto, 52

Hokkaido University, et al, SAE 922221, 1992.

40

Modifying diesel fuel to increase its volatility (i.e., tendency to evaporate) would

decrease the time required for each fuel droplet to evaporate in the combustion

chamber. More rapid and complete evaporation would result in more complete

combustion of the fuel and thus reduced PM emissions. However, the resultant

increased combustion pressures would probably require stronger engine components

to maintain durability at current levels. The effect of increased volatility on NOx is

also not well understood. It should be noted that the small increases in the volatility

of the diesel fuel referred to here would not lead to significant evaporative emissions.

Derivatives of vegetable oils or animal fats can be mixed with diesel fuel for

combustion in a diesel engine. Such fuel mixtures, known as biodiesel, have received

attention in Europe as a potential source of renewable fuel. Also, Congress identified

biodiesel as an alternative fuel in the National Energy Policy Act of 1992. The

biodiesel fuel mixture includes oxygen and, as with oxygenate additives, would likely

lead to a decrease in PM emissions while risking an increase in NOx emissions. The

costs and emission-reducing potential of these changes are not well understood or

quantified at the present time.

Additional modifications to diesel fuel can also reduce diesel exhaust emissions.

First, increasing the kinematic viscosity of diesel fuel has been correlated with reduced

PM emissions. Second, addition of detergents or other chemicals may reduce the 52

formation of deposits that impair precise control of fuel flow and can lead to increased

emissions.

Alternative Fuels

The use of fuels other than diesel fuel has received much interest in the context

of on-highway vehicles. The alternative fuels that have received the most attention are

natural gas (stored in both compressed gas and liquefied states), alcohols (methanol

and ethanol), and liquefied petroleum gas. Currently, only natural gas has received

any serious consideration as a potential fuel for locomotives. Thus, although other

fuels could someday be available for use in locomotives, this discussion is limited to

natural gas.

Natural gas is made up primarily of methane, but also tends to contain some

ethane, propane, butane and trace amounts of inert ingredients. It is a gas at standard

conditions, which requires that storage onboard a vehicle be approached differently for

natural gas than for liquid fuels. The current approach most utilized for on-highway

vehicles is to store it as a compressed gas in high pressure cylinders. However, the

high fuel usage rate of locomotives is problematic, due to compressed natural gas’

extremely low energy density (i.e., amount of energy per unit volume of fuel), and thus
 Alternative Fuels Today, July 15, 1997. 53

41

the space needed to store sufficient fuel. The second approach to storing natural gas

is to liquefy it and store it cryogenically in insulated containers. While much more

practical for locomotives, even this approach results in a much lower energy density

than diesel fuel, and a separate tender car for the fuel would be required for a liquefied

natural gas-powered locomotive which is traveling any great distance.

In contrast to diesel fuel’s ability to self-ignite in a compression ignition engine,

natural gas has a very high resistance to autoignition. In order to use natural gas in

a locomotive engine an ignition source must be provided. The two general approaches

to providing the required ignition source are diesel fuel pilot injection and spark

ignition.

The GasRail USA late-cycle, high-injection-pressure project is an example of the

former approach, and has shown NOx emission reductions of up to 75 percent with no

increases in HC and CO emissions. Under the pilot injection approach, a premixed 53

charge of natural gas and air is introduced into the combustion chamber. A small

amount of diesel fuel is then injected into the combustion chamber. The diesel fuel

autoignites, which in turn ignites the natural gas. Diesel fuel pilot injection systems

can be designed to use different ratios of natural gas to diesel fuel, but are generally

designed to maximize the use of natural gas. As a result, such systems typically use

natural gas for well over 90 percent of the energy needs of the locomotive. However,

they usually operate on pure diesel fuel at idle and low load operating points where

fuel consumption is low.

The second approach to igniting natural gas is to use a spark ignition system

similar to that used on gasoline engines. Since the spark ignition approach is a

dedicated natural gas system, it has the advantage of allowing an engine to be

optimized for natural gas. However, it is a much more significant departure from a

standard diesel engine than the pilot injection system. The pilot injection system is

essentially the addition of a natural gas fueling system to a diesel engine. As such, the

pilot injection system is much more suited to the retrofit of existing diesels than is the

spark ignition system.
 Fritz, S., “Exhaust Emissions from a Dual Fuel-Locomotive; Final Report,” Southwest 54

Research Institute, March 1992.

 Comments from W.C. Passie at Caterpillar to Docket A-94-31, “Emission Standards for 55

Locomotives and Locomotive Engines,” June 10, 1997.

42

Data show that natural gas strategies can be used to achieve significant

reductions in NOx and PM. Over the line-haul duty cycle, a dual-fuel locomotive

engine achieved NOx and PM levels of 4.2 and 0.33 g/bhp respectively. A dedicated 54

spark-ignition natural gas-fueled locomotive engine was shown to be capable of levels

as low as 2.0 g/bhp-hr NOx and 0.09 g/bhp-hr PM over a three mode cycle. However, 55

the HC and CO emissions did not meet the Tier 2 levels for either of these engines.

The long term durability of natural gas engines in locomotive use remains unknown.

Also, the use of natural gas would require that new refueling facilities be installed at

any rail yard which services natural gas-fueled locomotives. One potential area of

application would therefore be in switching and terminal operations.

Lubricants

Reductions in PM emissions can be obtained both by changes in the composition

of lubricating oil and by a reduction of the oil consumption rate. Refiners are

conducting research to formulate such lubricating oils that form less PM for truck

engines. Some of this research may or may not be applicable to locomotive engines,

since the additives used in lubricants for locomotive engines are different than those

used in truck engines. One possibility is to replace the metal additives commonly used

in lubricating oil with nonmetallic compounds in order to reduce the noncombustible

(ash) portion of the oil.

The use of synthetic oils or partial synthetic oils may reduce formation of PM

emissions. Conventional lubricating oil formulations evaporate over a wide range of

temperatures. The portion that evaporates at lower temperatures may diffuse into the

combustion chamber, increasing PM emissions. Synthetic oils can be formulated to

evaporate over a narrow, high-temperature range. Using such synthetic oils would

reduce the oil contribution to PM emissions. Partial synthetic oils, made by displacing

most of the more volatile portion of a conventional oil with synthetic material, may

yield equivalent results. Evaporated oil components would also be present to some

extent in the blowby gases introduced into the locomotive exhaust. Since HC exhaust

emissions from locomotive engines are already very low, and the measured values may

also include blowby gases, EPA does not believe that contributions from present oil

formulations to HC exhaust emissions are a problem.
 Acurex Environmental, “Locomotive Technologies to Meet SOP (sic) Emission 56

Standards,” Prepared for the U.S. Environmental Protection Agency, Contract No. 68-C5-

0010, August 13, 1997.

 Engine, Fuel, and Emissions Engineering Inc., “Cost Estimates for Meeting the 57

Proposed Locomotive Emission Standards,” Prepared for the U.S. Environmental Protection

Agency, September 12, 1997.

 A Roots-blower is a positive displacement pump driven by the crankshaft which is used 58

to force air into the combustion chamber.

43

3.4 Expected Availability of Technologies

The preceding sections were intended to provide a brief overview of the possible

technologies that manufacturers of locomotives and locomotive engines could employ

in complying with the requirements of this rulemaking. It should be emphasized,

however, that these are not mandated technologies and that manufacturers and

remanufacturers will develop their own optimized emission control strategies. EPA

has also determined that many of the technologies summarized above are not likely to

be feasible for use in the near term, at least for the Tier 0 and Tier 1 standards. This

section discusses the emission control strategies EPA expects to be available and costeffective at the time the locomotive emissions standards take effect. Additional

information on locomotive technology and costs is included in the docket.56,57

Tier 0 Locomotives

Tier 0 locomotives are those originally manufactured from 1973 to 2001.

Historically, two designs have dominated the locomotive engine market. The first is

a two-stroke engine design using uniflow-scavenging and unit injection. The second

is a four-stroke engine design using unit pump injection. Both designs are

turbocharged and aftercooled for line-haul applications. There are also a few thousand

Roots-blown two-stroke engines and naturally-aspirated four-stroke engines used in 58

switch locomotives.

Locomotives currently equipped with turbocharged engines will be able to

employ modified/improved fuel injectors, enhanced charge air cooling, injection timing

retard, and in some cases improved turbochargers, to reduce NOx emissions.

Moreover, it will be practical and cost-effective to equip some of these locomotives with

electronic controls as a means of avoiding the penalty in fuel efficiency often associated

with injection timing retard. Within the category of improved fuel injectors,

modifications are expected to include, injection rate changes, modifications to the

injector spray patterns, and reduced sac volumes. Remanufacturers could also use

limited modifications to the piston design, and enhanced smoke controls. Some of these

technologies are already available. In 1994, two-stroke engines using electronically

controlled unit fuel injectors were introduced into service in passenger locomotives
44

used in California. The electronics package is similar to a design used in heavy-duty

on-highway diesel engines. Also in 1994, electronic fuel injection was offered as an

option in four-stroke locomotive engines. Although there were some reliability

problems with the initial system, these problems have been resolved.

Enhanced charge air cooling will also be available, most likely taking the form

of improvements in existing air-to-liquid aftercooling systems. EPA expects that

engine coolant will continue to be employed as the cooling medium in most cases,

rather than a separate cooling system. Although this charge-air cooling should not be

too difficult to implement, some additional aftercooling hardware may be necessary

such as an additional pump and radiator and whatever lines and fittings may be

necessary to reroute the engine coolant. In the late 1980's a four-pass aftercooler was

introduced on some two-stroke designs, which proved to be more effective than the

older two-pass design. EPA anticipates that it will be cost-effective to replace nearly

all remaining two-pass aftercoolers with four-pass aftercoolers during the

remanufacturing process.

Overall, it appears likely that remanufacturers will achieve as much cooling of

charge air as possible, improve fuel systems and combustion chambers, while using

timing retard to the least extent possible so as to minimize negative effects on fuel

consumption. Some four-stroke engines may require improved turbochargers to

overcome problems with smoke during acceleration.

In the case of naturally-aspirated and Roots-blown engines, the tools available

to manufacturers for reducing emissions are modifications to the fuel system,

modifications to the combustion chamber and injection timing. In theory, these

engines could be retrofitted with turbochargers and charge air coolers, which if fueling

rates were not changed, would not increase power ratings and would lower peak

combustion temperatures and thereby NOx formation. Most of these locomotives are

employed in switching and terminal applications. It is probable that many of these

will be replaced with lower horsepower line-haul units as the latter are replaced with

newer, higher power units, per the current railroad practice.

Tier 1 Standards

Tier 1 locomotives are those that will be manufactured in 2002 through 2004.

Tier 1 locomotives will be able to incorporate the technologies outlined above for the

Tier 0 locomotives, but these technologies will likely be more effective in the Tier 1

locomotives because more optimization will be possible when they are included in the

original design than is possible with retrofit technology. There are additional

approaches that should also be available; these are discussed below.
45

Several recent locomotive models have already shown relatively low emissions

of HC, CO, and PM, and will be able to achieve significant NOx reductions through

minor incremental changes. These changes include a comprehensive emission

management system consisting of optimized fuel injection strategies through the use

of electronic controls and incorporation of separate circuit aftercooling. Separate

cooling systems, which have been introduced in recent years, have resulted in

enhanced effectiveness of the aftercooler. In these systems, separate circulation pumps

and radiators are used for the aftercooler rather than for the engine’s power

assemblies. Therefore, the coolant to the aftercooler is not subject to the heat added

by the engine.

Other technologies can be applied to many locomotive engines in addition to

electronic controls and enhanced aftercooling. Through the use of electronics and

enhanced aftercooling, further timing retard can be used to reduce NOx without a

negative impact on PM. Additional technologies that will be available for some models

include in-cylinder and turbocharger modifications. Changes in the configuration of

the combustion chamber and piston ring location may begin to appear in engines

complying with the Tier 1 standards. Increased compression ratios could be used to

reduce PM emissions and ignition delay. In addition, upgraded turbocharger designs

would help reduce smoke emissions by providing an improved response to transience.

In the case of switch locomotives, two approaches appear to be available to

manufacturers. One approach would be the continued use of large displacement

naturally aspirated engines employing electronic control of the fuel system, improved

fuel injection and improved combustion chambers. Another approach would be to use

turbocharging and other technologies used on line-haul locomotives, but with a

reduction in engine size to achieve the desired lower power rating. A reduction in

engine size could be achieved either through the use of fewer power assemblies of the

same configuration as those used on line-haul locomotives or by the use of a different

engine design than that used in line-haul applications. Locomotive manufacturers

could also use large nonroad engines (1000-2000 hp) that were originally designed for

use in non-locomotive applications. As with all other design choices, manufacturers

will base final decisions on costs (both initial and fuel usage), on durability, and on

serviceability and maintainability with respect to the availability of parts common to

both switch and line-haul locomotives. There is also the possibility, given the ability

of railroads to use older line-haul locomotives as switchers, that manufacturers could

choose to not offer new switch locomotives during the Tier 1 period.

Tier 2 Standards

The Tier 2 NOx standards will require HC and PM control as well as additional

NOx control. These standards will apply to locomotive engines originally

manufactured in 2005 and later.
46

Locomotive engine manufacturers have been in the process of developing new

engine designs with a focus on fuel economy and significantly increased power output,

to take advantage of developments in traction motor technology. In the past,

locomotive engines have been limited to about 4000 hp. This limitation was a direct

result of space constraints associated with the axle-hung DC motors. However, the

advent of high-performance AC motors has resulted in the availability of traction

motors that have a much higher power density than the old designs. As a result of this

change from DC to AC traction motors, new locomotive engines which are capable of

up to 6000 hp are now under development by the two major locomotive manufacturers.

Because they are in the process of developing these new engine models and have

been for several years, locomotive manufacturers are in a good position to meet the

Tier 2 standards. Both of the high-power engines currently under development are

four-stroke engines. (It should be noted that particulate emissions from two-stroke

engines have been observed to be largely made up of entrained lubricating oil.) Fourstroke engines, however, have shown lower PM emissions because they generally

achieve much better oil control. Furthermore, the best approach to designing engines

inherently lower in emissions and most effectively implementing such strategies is to

build them in from the beginning rather than adding them later in the process of a

retrofit. This is true for the fuel management, combustion chamber, charge air cooling,

electronic control, and other strategies discussed below and in Chapter 4.

A table listing potential Tier 2 technologies and resultant emission reductions

is presented in Chapter 4. In general, EPA expects that additional NOx and PM

emission reductions will be possible in these locomotive engines through continued

refinements in charge air cooling, fuel management, and combustion chamber

configuration, in conjunction with further improvements in electronic control systems.

Improved fuel management would include strategies such as increased injection

pressure, optimized nozzle hole configuration, and rate-shaping. Potential combustion

chamber redesigns include the use of reentrant piston bowls and increased compression

ratio. It may also be possible to reduce oil consumption by optimizing the ring pack

design and bore honing technique. However, reduced oil consumption could require the

use of more advanced oils to achieve comparable lubrication. Also, while EPA

anticipates that locomotive engine manufacturers will strive to avoid using EGR to the

greatest extent possible, the Agency believes that moderate rates of EGR may be used

in some instances. When the engine is operating at the lighter load steady-state

notches, EGR becomes a more attractive strategy. At these conditions, more excess air

is available, so engine performance and PM emissions are less sensitive to EGR.

Because the operation is steady-state, it makes optimization of the EGR and the fuel

and air much easier that for an engine operating under transient conditions.

Many of the more advanced technologies mentioned in section 3.3 do not appear

in the list of technologies that EPA expects will be used for compliance with the Tier

2 standards. This is because EPA cannot confidently project that the technical and/or
 Lizhong, S., et al., "Combustion Process of Diesel Engines at Regions With Different 59

Altitudes," SAE Paper 950857, 1995.

 Kapich, D., "Very High Speed Hydraulic Driven Supercharging System," SAE Paper 60

951822, 1995.

47

practical obstacles to these technologies will be overcome. However, it should be

remembered that the Tier 2 standards will not take effect for another seven years.

This represents a substantial amount of lead time, which will provide an excellent

opportunity for additional technological advances. Two emission control strategies that

have shown some promise are selective catalytic reduction and alternative-fueled

engines. These technologies and others in even more preliminary stages of

consideration may ultimately prove to be more attractive emission control alternatives

with sufficient development. Nevertheless, EPA cannot conclude that these

technologies will be available in the time frame being considered.

3.5 Adjustments for Ambient Conditions

Manufacturers and remanufacturers can incorporate various technologies to

account for changes in ambient conditions. The effects of changes in ambient

temperature can be minimized by controlling the rate of heat rejection in the

aftercoolers and engine cooling system. Current locomotives are already designed to

have a fairly constant engine coolant temperature over a broad range of temperatures.

This is achieved primarily by varying the flow of air past the radiator. Greater control

at cooler temperatures is possible using a thermostat type system to bypass or

partially bypass the heat rejection components of the cooling system (e.g., radiators)

unless the coolant reaches the appropriate temperature. The potentially adverse

effects of higher ambient temperatures can be reduced by increasing the cooling

capacity of the engine, where possible.

The effects of low barometric pressures can be minimized either by reducing the

amount of fuel injected or increasing the amount of air forced into the cylinder so that

the appropriate excess air ratio can be maintained. Although reducing the amount of

fuel injected at lower barometric pressures can result in maintaining emissions

compliance, a loss in engine power usually results. Current diesel engine designs have

been reported to operate with 24 percent less power and 5 percent higher specific fuel

consumption at elevations approaching 7,000 feet. An intermittent supercharger has 59

been developed for truck engines that assists the turbocharger at high altitudes to

compensate for lower air density effects.60
48

3.6 Reliability and Durability

EPA understands that the reliability and durability of locomotive engines are

important to the railroad industry. Any time that a locomotive breaks down on a track,

it can result in severely disrupted traffic flows, especially where the locomotive must

be repaired in place. The technology projected to be applied to meet the locomotive

standards has been applied to trucks and other applications. Experience to date

suggests that there is no reason that any of these technologies should inherently cause

any sort of reliability or durability problem for locomotives.

Although the emission control technologies described above are themselves

likely to be inherently reliable and durable, there may be a learning curve associated

with confidence in the application of these technologies to locomotives. With the seven

years of lead time given in this rule, potential learning curve difficulties should not be

a limiting factor. There will be adequate time for prototypes to be durability tested,

for demonstration fleets to prove out the reliability of these technologies, and for

upgrades and optimization to be implemented. Because of the importance of engine

reliability and durability to the railroad industry, EPA believes that locomotive

manufacturers will make sufficient efforts to prove out their new engine designs.
 Exception: existing switch locomotives will not be required to comply with the line- 61

haul duty-cycle standards.

 For locomotives, a duty-cycle is a usage pattern expressed as the percent of time in 62

use in each of the throttle notches.

49

4.0 Emission Standards and Supporting Analyses

This chapter describes the development of EPA’s emission standards for

locomotives. As will be described, the regulations require that cycle-weighted brakespecific HC, CO, NOx, and PM emissions from each new locomotive be: 1) below the

line-haul standards when weighted using line-haul duty-cycle; and 2) below the switch

standards when weighted using switch duty-cycle . The regulations also require that 61

smoke emissions be below the specified smoke standards. Compliance with these

standards is required throughout the full useful life of the locomotive. This chapter

also describes the development of the duty-cycles, useful life periods, and baseline

emission rates on which the numeric standards are based. Finally, this chapter also

analyzes feasibility of these standards.

4.1 Duty-Cycles62

EPA believes that the most cost-effective means of achieving national locomotive

emission reductions is to set standards for emissions weighted by typical in-use dutycycles. Unlike other vehicles which have a continuously variable throttle, locomotives

are limited to a predetermined number of throttle notches. Individual standards for

each throttle notch might be able to achieve similar emission reductions, but with less

flexibility, and thus, probably at a higher cost. This section describes the development

of the two duty-cycles used in this regulation, as well as the development of a

passenger locomotive duty-cycle that is presented here for informational purposes.

Industry Freight Locomotive Duty-Cycles

Industry has historically used two distinct types of duty-cycles for freight

locomotives: line-haul and switching. The term line-haul refers to the movement of

freight between cities or other widely separated points. Several previously-used linehaul duty-cycles are shown in Table 4-1. Switching refers to the process of assembling

and disassembling trains in a relatively small area (a switchyard); thus switching

operations are also often referred to as yard operations. Two historical duty-cycles for

switch locomotives are shown in Table 4-2. Dynamic braking is not included in these

cycles because switch locomotives are usually not equipped with this function.
50

Table 4-1

Historical Information -- Line-Haul Duty-Cycles

(Percent Time in Notch)

Throttle GE GE GE GE EMD EMD AAR

Position Min. Max. Average 1 Average 2 Heavy Medium

Idle 59.0 40.0 54.0 53.0 41.0 46.0 43.0

Dynamic 1.5 7.0 4.0 5.5 8.0 9.0 8.0

Brake

1 6.5 2.5 5.0 5.1 3.0 4.0 3.0

2 6.5 2.5 2.5 3.9 3.0 4.0 3.0

3 6.5 2.5 2.0 3.4 3.0 4.0 3.0

4 6.5 2.1 5.0 3.3 3.0 4.0 3.0

5 2.9 1.8 2.0 2.8 3.0 4.0 3.0

6 2.9 1.8 2.0 3.4 3.0 4.0 3.0

7 2.5 1.8 2.5 2.6 3.0 4.0 3.0

8 5.2 38.0 21.0 17.0 30.0 17.0 28.0

Table 4-2

Historical Information -- Switch Duty-Cycles

(Percent Time in Notch) 

Throttle Position ATSF EMD

Idle 77.0 77.0

Dynamic Brake 0.0 0.0

1 10.0 7.0

2 5.0 7.0

3 4.0 4.0

4 2.0 2.0

5 1.0 1.0

6 1.0 0.5

7 0.0 0.5

8 0.0 1.0
 EPA assumed equal time is notches 1 and 2 because some of the line-haul data did not 63

separate those notches from one another.

 The term train is used for line-haul, instead of locomotive, because many of the trains 64

for which data were reported included more than one locomotive in the consist. For

example, a given train could require 12,000 total horsepower for propulsion, which would be

accomplished with three 4,000 horsepower locomotives in series.

51

EPA Duty-Cycles

In response to a request by EPA, several freight railroads collected time-in-notch

data for both line-haul and switch operations. Amtrak also collected data for passenger

locomotive operations. The data were presented to EPA in different formats, but each

allowed the calculation of average time in each notch. It is important to note that not 63

all of the idle time reported corresponds to time during which the locomotive was not

moving. As much as one-third of idle time can be spent while a locomotive is coasting

(i.e., moving forward because of either gravity or momentum without any power being

applied to the traction motors).

In the case of line-haul operations, the data came from 63 trains operated by 64

five Class I railroads. Train operations were spread over many regions of the nation

and represented approximately 2,475 hours of freight train operations. Data on switch

operations came from two railroads and represented approximately 333 hours of switch

locomotive operations. Amtrak provided data from 20 locomotives covering

approximately 57,500 hours of operation.

These data were reviewed to identify duty-cycles applicable to line-haul, switch

and passenger operations. Results from the data collected by the railroads are

summarized in Tables 4-3 through 4-5 below. In addition to the average duty-cycles

developed from the current database, the highest and lowest individual percentages

of the time in notch from all line-haul and switch locomotive data were shown in

Tables 4-3 and 4-4. This information shows the presence of very wide variations

around the averages for the two types of operations.
52

Table 4-3

Current Locomotive Operations - Line-Haul Duty-Cycles

(Percent Time in Notch)

Data Source: 63 Trains

Throttle Average Highest Lowest

Position

Idle 38.0 77 1

Dynamic Brake 12.5 41 0

1 6.5 23 0

2 6.5 23 0

3 5.2 13 2

4 4.4 11 1

5 3.8 12 0

6 3.9 11 0

7 3.0 18 0

8 16.2 39 0

Table 4-4

Current Locomotive Operations - Switch Duty-Cycles

(Percent Time in Notch)

Data Source: 8 Locomotives

Throttle Average Highest Lowest

Position

Idle 59.8 82 23

Dynamic Brake NA NA NA

1 12.4 18 7

2 12.3 18 7

3 5.8 20 1

4 3.6 17 1

5 3.6 15 0

6 1.5 10 0

7 0.2 1 0

8 0.8 4 0
 The passenger duty-cycle is not used in the regulations, and is shown here only for 65

informational purposes.

53

Table 4-5

Current Locomotive Operations - Passenger Duty-Cycles

(Percent Time in Notch)

Data Source: 20 Locomotives

Throttle Average Highest Lowest

Position

Idle 47.4 60 40

Dynamic Brake 6.2 8 2

1 7.0 11 5

2 5.1 6 4

3 5.7 7 4

4 4.7 6 4

5 4.0 5 2

6 2.9 6 1

7 1.4 2 1

8 15.6 19 8

The average line-haul duty-cycle from current operations is generally consistent

with the historical cycles. Current operations, however, show higher usage of dynamic

brake than in any of the historical cycles. In the case of switching operations, the

current data show a lower percentage of time at idle and higher percentages of time in

notches 1 and 2 than are shown in the historical cycles. The historical cycles bracket

the results from current data for the other throttle notches.

EPA believes that it is more appropriate to use the results of the recent

operational data for this rulemaking since their source is known (while the exact

source of the information used to develop the historical cycles is not fully known).

Moreover, the data are known to represent operations in widely dispersed areas of the

nation. The three average duty-cycles (line-haul, passenger and switch) are 65

summarized in Table 4-6 below.
54

Table 4-6

EPA Estimated Duty-Cycles for Current In-Use Locomotive

 (Percent Time in Notch)

Throttle Notch Line-haul Passenger Switch

Idle 38.0 47.4 59.8

Dynamic Brake 12.5 6.2 0.0

1 6.5 7.0 12.4

2 6.5 5.1 12.3

3 5.2 5.7 5.8

4 4.4 4.7 3.6

5 3.8 4.0 3.6

6 3.9 2.9 1.5

7 3.0 1.4 0.2

8 16.2 15.6 0.8

Emissions Impacts of Duty-Cycles

EPA believes that requiring locomotives to comply with emission standards

using both a high-power duty-cycle (line-haul) and low-power duty-cycle (switch) will

not only achieve cost-effective national emission reductions, but will also minimize the

geographic variation in the reductions. The line-haul cycle is fairly representative of

a national average duty-cycle. However, because it weights high-power emissions so

heavily, it would be possible for a locomotive to comply with line-haul emission

standards with little or no emission reduction at idle. This is not an unreasonable

scenario to consider, especially for current locomotives, since the emission controls

expected to be employed are generally most effective at higher power levels. If such

a compliance strategy were allowed, then urban areas where locomotives are operated

more frequently at idle and in low power notches could potentially see little or no

emission reductions. This is why EPA is requiring that all locomotives be required to

comply with emission standards for both the line-haul and switch duty-cycles.

It should be noted that while the idle weighting factors for the two duty-cycles

are not that different from one another (0.380 and 0.598), the relative importance of

idle emissions in the two cycle-weighted emission calculations is very different. This

is because the calculation weights mass emission rates (g/hr), which can be nearly 100
55

times greater at full power (notch 8) than at idle. While idle emissions are not very

significant for the line-haul cycle, they can actually be more important than notch 8

emissions for the switch cycle. For example, consider a locomotive that has mass

emission rates of 700 g/hr at idle and 50,000 g/hr at full power. Using the line-haul

weightings, the weighted emission rates for idle and full power would be 266 (700 x

0.380) and 8,100 (50,000 x 0.162) g/hr, respectively. In this case, the contribution of

notch 8 emissions would be 30 times that of the idle emissions. On the other hand,

using the switch weightings, they would be 419 (700 x 0.598) and 400 (50,000 x 0.008)

g/hr, respectively. In fact, using the switch weightings, weighted emissions for all

notches will generally be of similar magnitude. This means that manufacturers and

remanufacturers would have a strong incentive to achieve significant emission

reductions for each notch.

While the available data indicate that duty-cycles for passenger locomotives are

different from those of freight locomotives, EPA believes that it is not necessary to use

a passenger-specific duty-cycle to achieve the desired emissions reductions from

passenger locomotives. The average passenger locomotive's duty-cycle is similar to the

average line-haul cycle, except that it includes significantly more idling time. Thus,

requiring all locomotives, including passenger locomotives, to comply with emissions

standards for the line-haul and switch cycles should achieve essentially the same

emission reductions as would be achieved by using the passenger cycle. Moreover, as

noted previously, manufacturers and remanufacturers are likely to reduce emissions

significantly in all notches, which would make duty-cycle concerns less significant. 

4.2 Useful Life

Definition of Useful Life

Useful life is the term EPA uses to designate the period during which a vehicle

is required to comply with emissions standards. For highway vehicles, the period of

compliance is usually expressed in terms of years and mileage, with the requirement

for compliance ending when either parameter is exceeded. Useful life periods currently

applicable to highway vehicles were originally intended to approximately correspond

to the median time and mileage at which a unit is scrapped or remanufactured. The

range of current highway vehicle useful life values are from 10 years and 100,000 miles

for light-duty vehicles (passenger cars) to 10 years and 435,000 miles (beginning in

2004) for heavy heavy-duty diesel engines (i.e., engines used in largest trucks).

For locomotives, EPA is explicitly defining useful life to be the period during

which a locomotive is designed to remain properly functional with respect to power

output and fuel economy. This definition recognizes that different designs of

locomotives can have different useful lives. EPA's approach is to specify default useful

life values, but require manufacturers and remanufacturers to specify longer useful

lives for locomotives that are designed to last significantly longer than the default
 Data are for ATSF remanufacturing between 1989 and 1994 of locomotives 66

manufactured 1973-1990. Essentially all of the locomotives in this data set were between

3000 and 4000 hp, with an average of approximately 3500 hp.

 EPA received other similar data from AAR regarding remanufacturing intervals. 67

These data have been placed in public docket A-94-31.

56

period. In some limited cases, EPA will also allow remanufacturers to specify shorter

useful lives for locomotives that are designed to last significantly less than the default

period, provided that the manufacturer can provide adequate technical justification.

This will only be allowed for engines that were designed for use in non-locomotive

applications.

This design period is very similar to the average period between

remanufactures, and takes into account the intense maintenance which most

locomotives undergo in use and the strong desire on the part of railroads for reliability.

Thus, EPA based its default useful life values on current information about

remanufacturing intervals. However, EPA did not set the default values to be equal

to current average remanufacture intervals. Rather, it projected future intervals,

based on current average intervals for the more recent locomotive models, and on

comments from industry regarding future technology.

Current Class I Remanufacturing Practices

Figure 4-1 shows remanufacturing interval data provided by AAR. Although 66

these data were collected from a single railroad (ATSF), they are fairly representative

of Class I remanufacturing practices for the current fleet. These data show a median

remanufacture interval of about 20,000 MW-hr (about 5.7 MW-hr per hp), and that

about 95 percent of locomotives are remanufactured before they reach 28,000 MW-hr

(about 8.0 MW-hr per hp). Similar data for mileage intervals, which are shown in

Appendix A, indicate a median remanufacture interval of about 700,000 miles.67

The figure also shows that there is an increase in the MW-hr remanufacturing

intervals for newer model locomotives. To some extent, this is caused by an increase

in engine horsepower. However, it also results from improved durability.

Manufacturers have made numerous improvements over the years to significantly

increase engine life. Railroads have also increased engine life by constantly improving

maintenance practices. EPA expects that these trends will continue, resulting in

marginal increases in median engine life each year.
57
58

Default Useful Life

EPA believes that the most appropriate way to determine useful life is set

default values, and then specify variations from that default on a case-by-case basis.

EPA believes that the default values in MW-hr should be equal to 7.5 times the rated

horsepower of the engine. For a typical 3500-hp locomotive, like those shown in Figure

4-1, this would mean a useful life period of 26,250 MW-hr.

In selecting this default value (i.e., 7.5 times horsepower), EPA sought a value

that would generally be feasible for the current fleet, even if there are no future

improvements in engine life, while ensuring the desired in-use control of emissions

from future locomotives under the most likely engine life scenario. While the selected

default value is somewhat greater than the median remanufacture interval for the

current fleet, EPA is confident that remanufacturers will be able to comply with the

standards during this period. EPA also believes that this value will be reasonably

close to the median remanufacturing interval that will be observed for Class I railroads

after these standards go into effect.

EPA recognizes that some Tier 0 locomotives will not be equipped with

megawatt-hour meters. For these locomotives, EPA has set the default useful life at

750,000 miles, or ten years, whichever occurs first. EPA is including the year

specification to account for switch locomotives, or other low-use locomotives. In

practice, EPA expects that most Tier 0 line-haul locomotives will reach the 750,000

mile point before ten years, while most Tier 0 switch locomotives will not. Moreover,

EPA is not confident that mileage accumulation values would be meaningful for switch

locomotives operating within a switchyard, where miles have little relevance.

Variations From Default Values

EPA expects that some future locomotives will be designed to be operated (and

actually will be operated in use) significantly beyond the default useful life values

defined here. In such cases, EPA will require that manufacturers and remanufacturers

specify a useful life that is longer than the default values. Generally, EPA would

require that the useful life value be at least as long as the median remanufacturing

interval of those locomotives in use. However, the Agency does recognize that there

could be cases in which the median remanufacturing interval would not be appropriate

for the useful life because the railroads were actually using the locomotives beyond

their legitimate design life. Such special cases would be indicated by very significant

increases in fuel consumption and/or decreases in reliability or power output, or

excessive maintenance costs before the locomotives were remanufactured.

Nevertheless, EPA believes these would be rare cases.
 Note: some additional information was subsequently provided by Caterpillar, Inc., on 68

a diesel engine appropriate for line-haul locomotives. 

 Procedures for Emission Inventory Preparation, Volume IV: Mobile Sources; U. S. 69

EPA, Emission Planning and Strategies Division, Office of Mobile Sources and Technical

Support Division, Office of Air Quality Planning and Standards; EPA-450/4-81-026d

(Revised).

59

EPA will allow manufacturers of nonroad engines used to repower locomotives

to petition for a shorter useful life. EPA recognizes that many of these engines will

have been designed for other applications where they may not expected to last as long

as a locomotive engine. In these cases, EPA will allow a significantly shorter useful

life, but will require substantial supporting information from the manufacturer.

4.3 Baseline Emission Rates

Locomotive manufacturers (EMD and GE) provided EPA with information on 68

locomotive emissions for HC, CO, NOx and PM. Most of the information was provided

at the time that EPA was developing revisions to the calculations for locomotive

emissions in "Compilation of Air Pollutant Emission Factors, Volume II: Mobile

Sources". The revisions to that document applicable to locomotives were published in

1992. EPA weighted these data by both the line-haul and switch duty-cycles to 69

estimate baseline emission rates. These cycle-weighted emission rates are shown in

Appendix B with the individual notch emission rates. Shown in the Appendix G are

the results of testing by Southwest Research Institute (SwRI) of late model

locomotives. The NOx and PM emission rates are also shown in Figures 4-2 and 4-3,

and summarized in Table 4-7. The HC and CO emission rates are shown graphically

in Appendix H.

Table 4-7

 Range of NOx and PM Emission Rates by Engine Type (g/bhp-hr)

Line-Haul Cycle Switch Cycle

NOx PM NOx PM

EMD 645 11.5-18.2 0.25-0.31 14.1-33.1 0.28-0.44

EMD 710 10.6-14.2 0.23-0.35 14.2-17.3 0.28-0.39

GE 10.3-15.0 0.22-0.41 9.2-15.8 0.22-0.86
 Data have been provided by AAR on more than one occasion. The first set of data 70

provided was collected in the early 1980s and was used in EPA's Report to Congress on

emissions from locomotives. That set of data was not employed in development of this

proposal because of its age.

60

In addition to the preceding information provided by manufacturers, information

was made available to EPA by AAR . The data supplied by AAR were collected by 70

Southwest Research Institute (SwRI) under contract to AAR. Only a portion of the

more recently provided information from AAR was utilized here since much of it was

collected at only three power levels.

It is important to recognize that there is significant uncertainty associated with

estimating baseline locomotive emissions, especially given the inherent variability of

uncontrolled emission rates (e.g., line-haul NOx emission rates vary from 10.55 to

15.54 g/bhp-hr) and the limited amount of data that are available. The following

analysis represents the Agency's best estimate of baseline emission rates.

Line-Haul Baseline Emission Rates

Line-haul emission rates were estimated for the 1990 fleet by cycle-weighting

the emission rates of each engine type by their respective in use populations and

horsepower. Similarly, weighted emission rates for later model locomotives were also

calculated. However, the data used for these later model years were less complete.

These analyses are summarized in Appendix C. EPA applied a deterioration factor to

the weighted average HC and PM emission rates to account for the expected difference

between average in-use emissions rates and emission rates calculated from test

engines or relatively new locomotives; the weighted average HC and PM emission rates

were multiplied by 1.15. This deterioration factor was estimated by EPA from its

experience with other diesel engines, and from confidential business information

provided by the locomotive engine manufacturers.

It should be noted that no attempt was made to account for potential differences

in in-use usage rates (i.e., whether newer models are used more frequently than older

models) for this baseline analysis. As can be seen from the data in the Appendices B

and C, there no clear trend of emissions of older locomotives having very different

emissions from the later model locomotives. The data from EPA's testing of several

later model locomotives showed some evidence of higher NOx emissions and lower HC,

CO, and PM emissions than were seen from the older locomotive models, but this trend

was not conclusive. Nevertheless, in some cases, the NOx emissions from these newer

locomotives were as high as 15 g/bhp-hr. Thus it is possible that, without EPA

regulation, the average in-use NOx emission rate would be much higher in the future

than is estimated for the current fleet. 
0 0.2 0.4 0.6 0.8 1

0

10

20

30

40

PM

NOx

Figure 4-3 Switch Cycle Emissions Data

NOx and PM (g/bhp-hr)

0 0.1 0.2 0.3 0.4 0.5

0

5

10

15

20

PM

NOx

Figure 4-2 Line-Haul Cycle Emissions Data

NOx and PM (g/bhp-hr)

61
62

Switch Baseline Emission Rates

Baseline emission rates for switch locomotives were estimated from cycleweighted average emission rates for the three switch engine models that are used in

the vast majority of existing switch locomotives. The same deterioration factor of 1.15

as was used in the line-haul analysis was also applied to the weighted average HC and

PM emissions.

The following table presents estimated baseline emission rates for both line-haul

and switch locomotives.

Table 4-8

Estimated Baseline In-Use Emission Rates (g/bhp-hr)

HC CO NOx PM

Line-Haul* 0.48 1.28 13.0 0.32

Switch** 1.01 1.83 17.4 0.44

 * Line-haul locomotives over the line-haul duty-cycle

 ** Switch locomotives over the switch duty-cycle

Baseline Smoke Emissions

The available data for smoke emissions are summarized in Appendix D. These

data are mainly for steady-state smoke levels. They show steady-state smoke levels

ranging from 0 to 35 percent opacity for current locomotives (with standard injection

timing) when measured with an optical path length of approximately one meter. Data

for newer, well-maintained locomotives show steady-state smoke levels that are

typically less than 10 percent.

4.4 Emission Standards

Gaseous and Particulate Emission Standards

The final emission standards for both the line-haul and switch duty-cycles are

shown in Table 4-9. Also shown in the table are the expected design targets and

average percent reductions from baseline emission rates. Based on the information

currently available, EPA has concluded that these standards are the most stringent

standards that can be achieved at a reasonable cost within the time period being

considered. EPA is not necessarily projecting that all existing locomotive

configurations will be able to achieve the Tier 0 NOx emission level at a reasonable

cost, but rather that average NOx emission levels will be below the Tier 0 standard.
 A compliance margin is a difference between the emission standard and the design 71

emission level. Manufacturers incorporate compliance margins to account for production

and testing variability.

63

Full compliance will probably require significant use of the emission averaging,

trading, and banking (ABT) provisions, and may require that some specific highemitting engine configurations be converted to other configurations for which emission

controls are more available. The Tier 0 standards for HC, CO, and PM will be

achievable without averaging. For the Tier 1 and Tier 2 standards, ABT will be

necessary for both NOx and PM since manufacturers may need this flexibility to

ensure compliance for all freshly manufactured locomotives during the first few years.

Absent ABT, less stringent standards or more lead time may have been necessary.

Given the emission control technologies that are expected to be available, EPA

is establishing standards that will achieve very significant reductions in NOx

emissions from the beginning of the program. However, the standards will not begin

to achieve significant reductions in the emissions of other pollutants such as HC and

PM until 2005. The Tier 0 and Tier 1 standards were set at levels that should allow

the use of retarded injection timing, which may cause emissions of HC and/or PM to

increase. This is appropriate because NOx is the only pollutant for which locomotive

emissions contribute more than one percent of the estimated national inventories

(locomotives contribute less than one-quarter of a percent for HC, CO, and PM). EPA

did consider more stringent Tier 0 and Tier 1 emission standards for HC, CO, and PM,

but concluded that the Tier 0 and Tier 1 emission standards for NOx might not be

achievable if significant reductions in HC, CO, and PM were also required.

Nevertheless, EPA does believe that average emissions for these pollutants will not

increase, even though the standards will allow the emissions to increase for some

specific locomotives. For these cases (which are denoted with asterisks in Table 4-9),

EPA is projecting that average emissions will remain unchanged from baseline levels.

In considering what emission standards would be achievable, EPA also

considered the need for compliance margins. Based on data contained in Appendix 71

E, it was assumed that manufacturers and remanufacturers would incorporate

different compliance margins into the locomotive designs for different pollutants. The

biggest compliance margin used was 20 percent for PM. The reasons for this are

testing variability and the potential for in-use deterioration. For HC and CO, 15

percent compliance margins were used because of HC and CO measurement variability

is significantly less than for PM. For NOx emissions, a 10 percent compliance margin

was used because both deterioration and test variability are expected to be less of a

concern for NOx than they are for other pollutants. This 10 percent margin is higher

than the average compliance margin for 1993-1995 on-highway diesel engines that is

shown in the Appendix E (8 percent) because EPA believes that manufacturers and

remanufacturers will incorporate slightly larger compliance margins to account for the

additional risk associated with the extensive in-use testing program.
64

It should be emphasized that the estimated percent reductions are the

reductions from the estimated 1990 baseline levels. As was noted earlier, there is some

reason to believe that NOx emission rates would increase significantly (and HC and

PM could decrease) in the future without these emission standards. Thus, the true

reduction of the Tier 2 NOx standard, relative to some of the locomotives currently

being produced, could be as high as 67 percent. The HC and PM reductions, on the

other hand, could be somewhat lower.

Table 4-9

Emission Standards and Expected Emission Reductions

Standard In-Use Emissions Percent Reduction

(g/bhp-hr) (g/bhp-hr)

Tier 0 Tier 1 Tier 2 Tier 0 Tier 1 Tier 2 Tier 0 Tier 1 Tier 2

LineHaul

Cycle

NOx 9.5 7.4 5.5 8.6 6.7 5.0 34% 49% 62%

PM 0.60 0.45 0.20 0.32* 0.32* 0.16 0% 0% 50%

HC 1.0 0.55 0.30 0.48* 0.47 0.26 0% 3% 47%

CO 5.0 2.2 1.5 1.3* 1.3* 1.3* 0% 0% 0%

Switch

Cycle

NOx 14.0 11 8.1 12.6 9.9 7.3 28% 43% 58%

PM 0.72 0.54 0.24 0.44* 0.43 0.19 0% 2% 56%

HC 2.1 1.2 0.60 1.0* 1.0* 0.51 0% 0% 50%

CO 8.0 2.5 2.4 1.8* 1.8* 1.8* 0% 0% 0%

* Baseline emission level

Smoke Standards

EPA is setting both "steady-state" and "peak" smoke standards for locomotives.

These standards are shown in Table 4-10. The steady-state standards will apply to

locomotive exhaust after the transition period during which the fueling rate is slowly

increased (typically within 15 seconds) after a notch change. The peak standards apply

to all times, but are intended to limit smoke during the transition period. The 3-second

and 30-second standards apply to the maximum smoke level observed during any

continuous 3-second and 30 second period, respectively. The same peak standards

apply to all tiers of standards, while the steady-state standards become more stringent

with each tier. There are several reasons for this. First, the Agency believes that

steady-state smoke levels are more environmentally significant than peak levels for

locomotives because of the largely steady-state manner in which locomotives are

operated. Thus, it is more critical that the steady-state standards be sufficiently
65

stringent. Second, EPA is more confident that Tier 1 and Tier 2 locomotives will be

able to comply with more stringent smoke standards at steady-state than they will

during the transition period after notch changes. Finally, EPA is concerned that overly

stringent peak standards might adversely affect locomotive performance, and that such

an effect might be unwarranted, given the marginal value of lower peak smoke

standards.

Table 4-10

Smoke Standards for Locomotives

(Percent Opacity for One-Meter Path Length)

Steady-state 30-sec peak 3-sec peak

Tier 0 30 40 50

Tier 1 25 40 50

Tier 2 20 40 50

Alternate Emission Standards

The general emission standards discussed previously are based on an analysis

of the potential for emission reductions from diesel-powered locomotives. However,

EPA recognizes that locomotives powered by alternatively-fueled engines could

potentially have even lower emissions for some pollutants, while having difficulty

complying with the standards for other pollutants. Therefore, EPA is establishing an

optional alternate set of standards that could be applied to locomotives which operate

on alternative fuels. The alternate standards allow higher CO emissions, but also

require lower particulate emissions. Although these alternate standards are primarily

intended to address issues associated with alternative fuels, EPA intends that they be

available for application to any locomotive. Manufacturers and remanufacturers would

be allowed to certify to the alternate CO standards instead of the normal standards,

as long as they also comply with the more stringent alternate PM standards, as well

as the normal NOx and hydrocarbon standards. They will not be allowed to mix the

alternate CO standards with the primary particulate standards for a single engine

family.

In developing these alternate standards, EPA focused on the emission

characteristics of current natural gas-fueled locomotives. Such locomotives generally

have higher (and more difficult to control) CO and hydrocarbon (i.e., total hydrocarbon)

emissions than diesel-fueled locomotives, but lower PM emissions. The status of

attainment for CO is much better nationwide than that for PM. Thus, it would be

inappropriate to effectively defer the introduction of low-PM technologies like natural
66

gas engines from market because they would have difficulty in complying with the CO

standards. EPA believes that the environmental benefit of the additional PM

reductions from these standards for this limited number of locomotives is greater than

the environmental cost associated with allowing somewhat higher CO emissions. 

4.5 Feasibility and Compliance with Standards

Manufacturers and remanufacturers will be required to comply with these

standards during certification, production and in-use. This section discusses the ability

of manufacturers and remanufacturers to comply with these requirements. Additional

information regarding technological feasibility can be found in Chapter 3.

Tier 0 Certification

Table 4-11 outlines technologies that EPA believes will be available for

retrofitting Tier 0 locomotives in 2000. The projected emission reductions listed in the

table represent the reductions that would be expected for a typical Tier 0 locomotive.

However, the existing fleet is diverse, and the effectiveness of these technologies will

vary from model to model. Based on these projections, EPA has determined that the

Tier 0 standards being adopted are the most stringent standards that can be adopted

for the existing fleet. Both the manufacturers and the railroads have agreed with EPA

that these standards are feasible, but that they will require extensive use of averaging,

and may lead to a few locomotive models being removed from service. Compliance with

the Tier 0 standards can be considered more precisely by dividing the subject

locomotives into three groups: 1) older and low-volume locomotives; 2) recent and highvolume locomotives with relatively low PM and smoke emissions; and 3) locomotives

requiring significant smoke and particulate control.

Remanufacturers of the first group of locomotives are expected to be able to

comply largely by significant retarding of the injection timing. Such an approach,

however, will result in a one to two percent increase in fuel consumption. The degree

of timing retard needed can be lessened by using enhanced charge air cooling such as

changing from a two-pass to a four-pass aftercooler. In some cases, remanufacturers

of such locomotives are expected to use credits generated by other engine families with

more advanced emission controls. For especially high-emitting locomotives,

remanufacturers might also reconfigure the engine to more closely resemble other

lower emitting configurations. Many improvements have been made over the last

decade such as advances in fuel injection systems and turbocharger designs which

could be applied to older engines. Also, it is expected that some of the old, inefficient

locomotives will be removed from service instead of being rebuilt.

Manufacturers have indicated that, for most engine designs, the NOx emission

standard is technologically feasible using technologies that can be incorporated

during remanufacture. One locomotive engine design has shown unusually high
67

emissions and is not expected to be able to meet the standard without more

extensive retrofitting. However, the averaging and banking provisions of this

rulemaking are expected to allow these locomotives to comply with the standard,

especially since the number of these locomotives which are still in service is not very

large.

Table 4-11

Tier 0 Locomotive Technology and Effectiveness

(Expressed as Percent Reduction from Baseline; Increases Shown in Parentheses)

Technology HC CO NOx PM Smoke BSFC

Timing retard (5-15%) (5-10%) 15-25% (10-20%) worse (1-2%)

Electronic control 0-10% -- 0-10% 0-5% better 0-1%

Fuel injection* 5-15% 5-10% -- 10-20% better 0-1%

Improved turbocharging 0-10% 0-5% (0-5%) 0-5% better 0-0.5%

4-pass aftercooling -- -- 5-10% 0-5% even (0-1%)

Engine modification 0-5% 0-5% -- 0-5% even --

Puff limiter -- -- -- -- better --

COMBINED 10-20% 0-10% 30-45% 0-15% better (2)-1%

REDUCTIONS

* improvements in nozzle geometry, sac volume, and fuel injection control for mechanical and electronic

injectors

For the second group, where the number of locomotives within a family is high, or

where the remaining service life is expected to be long, railroads are likely to desire

higher technology remanufacturing kits that will minimize possible fuel consumption

effects. To provide such kits, remanufacturers will likely use optimized electronic fuel

injection systems that provide some of the NOx benefits of timing retard without the

fuel consumption penalty. In some cases, remanufacturers will likely make some

improvements to the aftercooling systems such as using four-pass heat exchangers.

There are also opportunities for lower emissions and fuel consumption through the use

of improved fuel injectors. Potential modifications to the fuel injection system would

include injection rate, nozzle spray geometry, and reduced sac volumes. Since such

approaches will likely result in NOx emissions well below the Tier 0 standards, many

of these engines are expected to generate emission credits. Although many of the new

locomotive technology improvements offer the potential for lower fuel consumption,

some sacrifices may need to be made to fuel economy improvements to achieve lower

emissions. Ultimately, each remanufacturer will make choices between first cost and

fuel costs so as to minimize total cost of compliance over the remaining portion of the

locomotive's total life.
68

Application of injection timing retard to the last group might be limited because

of the PM and smoke increases that would result. However, turbocharger designs have

improved in the past decade, and improved turbocharging allows for reductions in

smoke and PM. In addition to improved turbochargers, such locomotives are expected

to require significant improvements to aftercooling systems (e.g., more efficient heat

exchangers) and electronically controlled fuel injection systems. They might also

require combustion chamber redesign to reduce PM and smoke emissions by achieving

more complete combustion. Some of these locomotives are expected to use NOx

emission credits to the extent that they are available.

It is important to note that the ability of remanufacturers to fully comply with the

Tier 0 emission standards is limited to some extent by their ability to devote adequate

resources to developing emission controls for multiple engine families. Therefore, EPA

is phasing-in the Tier 0 requirements to allow remanufacturers to focus their resources

sequentially, beginning with the latest models. The initial focus on later model

locomotives is appropriate because these locomotives are more heavily used than older

locomotives. This approach has the additional benefit of minimizing market

disruptions for small businesses that participate significantly in the remanufacturing

of the older locomotives. 

Tier 1 Certification

It is likely that both major locomotive manufacturers will be able to comply with

the Tier 1 emission standards by further modification of their current production

locomotives beyond the expected changes necessary to comply with the Tier 0 emission

standards. The technologies that will be available are listed in Table 4-12. In

addition, both major manufacturers are planning to introduce new low-emission

locomotive designs, and have indicated that they will be able to comply with the Tier

1 emission standards by January 1, 2002. In fact, once optimized, these new

locomotive models will be the models that the manufacturers use to comply with the

Tier 2 standards. Thus, the manufacturers may be able to use these new models to

generate emission credits, which could be used to ease compliance for their current

models. However, even though EPA believes that some locomotive models would be

able to comply with standards more stringent than the Tier 1 standards before

January 1, 2005 (which is when the applicability of the Tier 1 standards ends for

freshly manufactured production), EPA believes that the Tier 1 standards are the most

stringent standards that will be feasible on average for all freshly manufactured

production during the 2002-2004 time frame.
69

Table 4-12

Tier 1 Locomotive Technology and Effectiveness

(Expressed as Percent Reduction from Baseline; Increases Shown in Parentheses)

Technology HC CO NOx PM smoke BSFC

Timing retard (10-25%) (5-15%) 20-30% (15-25%) worse (1-2%)

Electronic control 10-15% 0-5% 10-15% 5-10% better 0-2%

Fuel injection* 10-20% 5-10% -- 10-20% better 0-1%

Improved turbo- 5-10% 0-5% (0-5%) 0-5% better 0-0.5%

charging

Separate circuit -- -- 10-15% 0-5% even (0-1%)

aftercooling

Combustion chamber 0-5% 0-5% -- 0-5% even 0-0.5%

Engine modification 0-5% 0-5% -- 0-5% even --

Puff limiter -- -- -- -- better --

COMBINED 10-20% 0-10% 45-55% 0-20% better (2)-2%

REDUCTIONS

* improvements in nozzle geometry, injection pressure, sac volume, and fuel injection control for

electronic injectors

Tier 2 Certification

Manufacturers will need to perform significant work to apply available onhighway emission control technology to locomotives to meet the Tier 2 standards.

However, because the Tier 2 standards do not go into place until 2005, there will be a

relatively long lead time thus sufficient opportunity for technological development,

prove out, and certification.

On-highway diesel truck engines have shown large reductions in HC, NOx, PM,

and smoke over the past 25 years while still increasing power and fuel economy. Many

of the technologies developed for highway applications are expected to be able to be

applied to locomotives. Therefore, much of the experience gained by the truck engine

manufacturers can be applied to locomotive engine designs. Table 4-13 presents

emission reductions achieved from heavy-duty on-highway diesel engines and those

anticipated for locomotive engines.

Chapter 3 describes the technologies that will likely be used on locomotive engines

to meet the Tier 2 standards. It should be noted that these are generally similar to

systems being used on truck engines today. EPA believes that manufacturers would

make use of some of these strategies regardless of emissions regulations in order to

satisfy customer demands for higher power and better fuel economy. Given the long
70

lead time, EPA believes that the manufacturers will be able to make use of these

technologies to meet the Tier 2 standards. Table 4-14 includes the technologies that

EPA expects will be used to meet the Tier 2 standards as well as the approximate

effectiveness of each strategy.

Table 4-13

Emission Reductions for Trucks and Locomotives

HC CO NOx PM

On-Highway Heavy-Duty Diesel Engine History (HD-FTP transient cycle)

1988 Truck Emission Standards (g/bhp-hr) 1.3 15.5 10.7 0.6

1998 Truck Emission Standards (g/bhp-hr) 1.3 15.5 4.0 0.1

2004 Truck Emission Standards (g/bhp-hr) 0.5* 15.5 2.0* 0.1

Percent Reduction Achieved in Past 10 Years 0% 0% 63% 83%

Percent Reduction Anticipated in 2004 62% 0% 81% 83%

Locomotive Engine Projections (based on line-haul cycle)

Baseline Locomotive Emission Levels (g/bhp-hr) 0.50 1.3 13 0.32

Tier 2 Emission Standards (g/bhp-hr) 0.30 1.5 5.5 0.20

Design Target w/ Compliance Margin (g/bhp-hr) 0.26 1.3 5.0 0.16

Percent Reduction Required in 2005 47% 0% 62% 50%

* Nominal values, based on NMHC+NOx standard of 2.4 g/bhp-hr or 2.5 g/bhp-hr provided that NMHC

does not exceed 0.5 g/bhp-hr.

EGR will likely be one of the primary technologies used by truck engines to meet

future emission standards. However, EPA agrees with locomotive manufacturers that

using EGR on locomotive engines at this time would require overcoming significant

technical challenges. Moreover, EGR may not provide the same degree of emission

reduction for locomotives as for trucks since it would not likely be used during high

power operation which is more prevalent in the locomotive duty-cycle than the Federal

Test Procedure transient cycle for truck engines. Nevertheless, it is possible that

moderate rates of EGR may still be used in some instances.

Other technologies that may be on the horizon but are not expected to be available

for widespread use in 2005 are SCR and natural-gas fueled engines. At this time,

there are durability concerns associated with the vibrational and thermal stresses that

would be seen by catalysts used in locomotive applications, and more investigation is

needed on the durability and effectiveness of SCR. More investigation is also needed

on both the operation of, and the fuel infrastructure needed for, natural-gas fueled

locomotive engines. Nevertheless, EPA hopes that the potential to generate emission
71

credits will provide an incentive for manufacturers and/or railroads to participate in

demonstration programs that could ultimately lead to the viability of one or both of

these technologies.

In summary, EPA believes that the NOx and PM standards established for Tier

2 locomotives are the most stringent standards that will be feasible in 2005. While

EPA's analysis suggests that slightly more stringent standards could potentially be

feasible if the effectiveness of each of the technologies listed in Table 4-14 were at the

maximum level within the projected range, EPA believes that this is unlikely to be the

case. In addition, there is some uncertainty in EPA's estimate of current baseline

emissions. Thus, even if a 70 percent reduction in NOx emissions is ultimately

possible, that does not guarantee that a 3.9 g/bhp-hr NOx emission rate (i.e., 30

percent of 13.0 g/bhp-hr) would be achievable. EPA believes that the NOx and PM

standards being established appropriately balance the need for maximum stringency

with the uncertainty inherent in the analysis.

Table 4-14

Tier 2 Locomotive Technology and Effectiveness

(Expressed as Percent Reduction from Baseline; Increases Shown in Parentheses)

Technology HC CO NOx PM smoke BSFC

Four-stroke cycle 0-10% 0-10% -- 0-20% better --

Timing retard (10-25%) (5-15%) 20-30% (15-25%) worse (1-2%)

Electronic control 10-15% 0-5% 10-15% 5-10%** better 0-2%

Fuel injection* 15-25% 5-10% -- 20-30% better 0-1%

Rate shaping 0-5% 0-5% 15-25% 5-15% even --

Improved turbocharging 10-15% 5-10% (0-5%) 5-10%** better 0-0.5%

Separate circuit -- -- 10-15% 0-5% even (0-1%)

aftercooling

Improved oil control 5-10% -- -- 5-15% better --

Combustion chamber 5-10% 0-5% -- 0-5% even 0-0.5%

Puff limiter -- -- -- -- better --

COMBINED 50-65% 10-25% 60-75% 45-60% better (2)-2%

REDUCTIONS

* improvements in nozzle geometry, injection pressure, and sac volume

** greater reductions would be expected during transient operation.

It is worth noting that EPA's analysis also projects reductions in HC and CO

emissions that are larger than required by the Tier 2 standards. However, EPA

believes that the projected emission reductions will probably be obtained even without
72

tighter standards for HC and CO, since they are projected to result from the

technologies required to comply with the PM standards. Given that the primary focus

of this rulemaking has been to reduce NOx emissions, EPA believes that it would be

inappropriate to risk compromising the feasibility of the NOx standards by setting very

stringent HC and CO that could limit the ability of manufacturers to use injection

timing retard to lower NOx emissions.

Production Line and In-Use Compliance

Compliance with the new emission standards during production will require that

manufacturers and remanufacturers continue (or institute) proper quality assurance

programs to limit deviation of production locomotives from the design specifications.

Nevertheless, small but significant production variability is expected. As mentioned

previously, EPA expects that manufacturers and remanufacturers will address this

variability by incorporating compliance margins into their designs.

Because of the generally high expectations that railroads currently have for in-use

locomotive performance in terms of power output, fuel consumption, and reliability,

compliance with these standards in use during the full useful life is not expected to be

significantly more difficult for manufacturers and remanufacturers than compliance

at certification. In some cases, however, it may require somewhat more rigorous

maintenance than some railroads are currently practicing. This will be especially true

for Tier 1 and Tier 2 locomotives. Railroads may need to inspect, repair, and replace

(as needed) fuel injectors or power assemblies more frequently than in current practice.

They may also need to more carefully inspect the condition of the turbocharger and

aftercooler systems and repair or replace these components more frequently.

High Altitude and High Ambient Temperature Compliance

Compliance with the emission standards under different ambient operating

conditions may require that manufacturers and remanufacturers design their

locomotives to be relatively insensitive to changes in ambient conditions or to adjust

to such changes to the extent possible. Manufacturers and remanufacturers will need

to continue their practice of designing control features into their locomotive aftercooler

systems that minimize the effect of ambient temperature on the charge air and

combustion temperatures. For barometric pressure (or altitude), manufacturers and

remanufacturers will need to design control features into their locomotive fuel and/or

charge air systems that will minimize the effect of ambient pressure on the engines

air/fuel ratio. This will likely require either charge air designs that compensate for

changes in ambient pressure, or deration of the horsepower out by decreasing the

fueling rate. This technology is employed on many locomotives today.
73

5.0 Test Procedures

This section describes the Federal Test Procedure (FTP) for locomotives. Since the

FTP is, in essence, a part of the emission standards, it is necessary for it to be very

specific in order to minimize testing variability. Thus, the FTP should be considered

the standard test procedure. However, as with EPA's test procedures for other vehicles

and engines, the locomotive test regulations also allow alternate test procedures to be

used, provided that they have been demonstrated to yield results equivalent or

superior to those obtained from the FTP.

The FTP for locomotives is a nominally steady-state test procedure that measures

gaseous (HC, CO, CO , and NOx), particulate, and smoke emissions from locomotives; 2

that is, a procedure wherein measurements of emissions are performed with the engine

at a series of steady-state speed and load conditions. Measurement of emissions would

actually be performed during both steady-state operations and during the limited

periods of engine accelerations between notches. The reason for this is that in-use

locomotive operation is not truly steady-state. Rather, locomotive operation is a

combination of short periods of largely steady-state operation at individual notches,

and short transient periods between notch changes. In developing the final test

procedure, EPA sought to ensure that all measured emission rates are representative

of actual in-use emissions.

The test procedures, other than the test sequence, are based largely on the test

procedures previously established for on-highway heavy-duty diesel engines in 40 CFR

86 Subparts D and N. Specifically, the raw sampling procedures and many of the

instrument calibration procedures are based on Subpart D, and the dilute particulate

sampling procedures and general test procedures are based on Subpart N. The most

significant aspects of the test procedures are described below. 

5.1 Locomotive Testing

In previous regulation of mobile sources EPA has based its emission standards on

either chassis testing (e.g., on-highway light-duty vehicles) or engine testing (e.g., onhighway heavy-duty engines). In general, chassis testing is preferred because it more

closely represents the operation of the vehicle in actual use. However, EPA recognizes

that it can be impractical to require chassis testing for some sources. For example,

EPA does not currently require chassis testing for on-highway heavy-duty engines

because it would require an extremely large chassis dynamometer, and because a given

engine model is often used in very different vehicle configurations. For this rule, EPA

determined that it is appropriate to base the emission standards on chassis testing (or

locomotive testing), as is described below.
74

Chassis Testing

Chassis testing for locomotives is reasonably practical because of the inclusion of

electrical alternators as part of standard locomotive design. The power output of the

engine, which is converted to electrical power by the alternator, can easily be

dissipated as heat during an emission test. Thus, EPA believes that engine testing is

not necessary, except for the few specific cases described in the "Engine Testing"

section. Moreover, EPA believes that chassis testing offers significant potential

advantages over engine testing; that is, there are problems that can occur with engine

testing, but that would not be expected with chassis testing. First, the performance

of engine coolant and intake air systems used during engine testing often deviate

significantly from the performance of the actual locomotive systems in use. Second,

engine test facilities are often designed with engine control systems that are different

than the actual in-use systems. This is particularly important for smoke

measurements, since one of the most common means of controlling smoke is to reduce

the fueling rate during transients. Thus, if the fueling controls do not match the in-use

fueling controls, then neither will the smoke measurements. Third, it can be difficult

to simulate the actual in-use load on the engine during engine testing. Each of these

three potential problems could significantly affect testing accuracy of engine testing.

However, the most important problem with engine testing is that engine testing would

be extremely impractical in use, because it would require pulling the engine out of the

locomotive.

Engine Testing

EPA sees two cases in which it is somewhat reasonable to not require chassis

testing of locomotives. First, it is acceptable to allow certification data to be generated

from engine testing of a development engine. The concerns about accuracy are

lessened to some degree by the fact that engine family would eventually be required

to be chassis tested as part of the in-use testing programs. Similarly, EPA is willing

to allow production line testing be conducted on the engine.

The Agency believes that when engine testing is conducted, it is critical that the

testing be as representative of actual locomotive operation as can practically be

achieved. Thus, EPA is requiring that important operating conditions such as engine

speed, engine load, and the temperature of the charge air entering the cylinder be

essentially the same as in a locomotive in use.
75

5.2 Test Sequence

Background

Locomotives differ significantly from road vehicles, in that the power from the

engine is transmitted to the drive wheels by electrical and mechanical components,

instead of only by mechanical components. With road vehicles, the relationship

between engine speed (rpm) and vehicle speed (mph) is mechanically dictated by the

gear ratios in the transmission and in the final drive. Locomotives, on the other hand,

are powered by an engine through an electric alternator to electric motors that are

connected to the drive wheels of the locomotive. The effect of this is that a locomotive

engine is operated at a desired power output and corresponding engine speed without

being constrained by locomotive speed. With the electrical coupling between the

engine and the drive wheels of a locomotive, engine lugging is not possible.

Another design feature unique to railroad locomotive engines is the design and

operation of the throttle. Power settings for railroad engines (throttle position)

generally include eight discrete positions or notches on the throttle gate in addition to

idle and the dynamic brake function. Each throttle notch position is numerically

identified, with notch position one being the lowest power setting (other than idle) and

position eight being maximum power. Because of this design, each notch on the

throttle corresponds to a discrete setting on the fuel delivery system of the engine.

These are the only engine power settings at which the locomotive can operate. The net

effect of this method of control is that the engines can operate at only eight distinct

combinations of fueling rate, power output and engine speed (in addition to idle and

dynamic brake).

As described in Chapter 4, data collected by the freight railroads were recorded

on throttle clocks with a capability for recording throttle position on a second-by-second

basis. This allowed the analysis of the lengths of time that the throttle was

continuously in each throttle notch. The data were reviewed to determine the

continuous periods of time that locomotive engines typically remain at discrete power

settings. These results are summarized in Table 5-1 for times continuously in notch.

Inspection of the data shows that the time that locomotives are continuously operated

at a given power level is typically relatively short. Only for idle, dynamic brake and

notch 8 does the average time in notch exceed one minute. There are two reasons for

this. First, it is often necessary for locomotives to slow down for safety purposes as

they cross intersections in urban areas. Second , even when a constant locomotive

speed is allowed, it often requires that the engineer constantly adjust the throttle to

account for subtle changes in grade. 
76

Table 5-1

Average Time Continuously in Throttle Notch (Minutes)

Throttle Notch Line-Haul Switching All Operations

Idle 2.8 1.7 2.5

Dynamic Brake 5.6 NA 5.6

1 0.5 0.5 0.5

2 0.5 0.5 0.5

3 0.5 0.5 0.5

4 0.5 0.3 0.5

5 0.5 0.9 0.5

6 0.6 0.4 0.6

7 0.5 0.3 0.5

8 4.9 0.9 1.2

AAR provided continuous traces of NOx emissions from locomotives manufactured

by both GE and EMD, under the following two conditions. First, starting with the

engine at idle, NOx concentration in the exhaust was measured continuously as engine

power was increased to full power and returned to idle. The time in each throttle notch

was one minute during both increases and decreases in power. In the second test, the

same sequence of power settings was employed but the time in each notch was

increased to three minutes. Results from the testing performed are shown in Appendix

M. The results of this testing showed: 1) that NOx concentrations in the exhaust

during decreases in power repeated the values measured during increases in power,

2) that for current locomotive calibrations, equivalent NOx results would be obtained

from the one minute in notch test and the three minutes in notch test, and 3) that the

values obtained from the short times in notch tests equaled results obtained after

prolonged periods of equilibration.

Sequence for Testing

The test sequence for locomotives and locomotive engines calls for the locomotive

or engine to be operated at idle, dynamic brake and at the eight throttle notch

positions. The test sequence begins with the engine at idle and at operating

temperature and proceeds through dynamic brake and each power level to rated power.

To begin the sequence, the engine is started, if not already running, and warmed up

to normal operating temperature in accordance with warm-up procedures for in-service

locomotives as specified by the manufacturer. For locomotive testing, the engine
77

remains in the locomotive chassis, and the power output would be dissipated as heat

from resistive load banks (internal or external). The engine is considered to be warmed

up, and ready for emissions testing when coolant and lubricant temperatures are

approximately at the normal in-service operating temperatures for these materials as

specified by the manufacturer. After the engine has reached normal operating

temperature, the engine is operated at full power (i.e., highest power notch) for 5

minutes, then returned to idle, or low idle if so equipped. Testing must be commenced

within 15 minutes after the end of the 5 minutes of full power to prevent the engine

from cooling off significantly. The 5-minute period at full power is intended to ensure

that the engine is at a realistic operating temperature, and to improve test

repeatability. 

EPA is not including engine starting as part of the test procedure because the

starting of locomotive engines which are fully cooled to ambient conditions seldom

occurs in use. Locomotive engines tend not to be shut down, especially in cold weather,

because it can be difficult to start these engines if they are allowed to cool to relatively

low ambient temperatures and because of the potential for engine damage due to

leakage of coolant. When the engines are shut down, restarts are generally performed

before significant cooling of the engine occurs to avoid or minimize restart problems

and coolant leakage problems. 

Measurement of exhaust emissions, fuel consumption, power output, etc. begins

with the locomotive idling, after the engine is warmed up. These measurements

continue as the locomotive is operated in each notch. The minimum duration of each

test point is 6 minutes, except for the maximum power point (notch 8), where the

minimum duration of operation is 15 minutes. EPA concluded that longer periods of

notch operation are not required to develop adequate test data. The most timeconsuming requirement of emissions measurement is the time required to sample

particulate matter. When the highest feasible particulate filter face velocity is

employed, minimum sample time required to collect accurate particulate material

samples from current locomotives is about four minutes per engine power level. This

four minute value was increased to six minutes to provide sufficient time for accurate

sample collection, especially under the Tier 2 standards for particulate emissions. In

cases where a manufacturer is concerned about measurement variability, it will be

allowed to perform replicate tests and to use the average of the replicate

measurements. However, a manufacturer would not be allowed to replicate only tests

that are high. If a manufacturer chooses to replicate tests, then it must replicate all

tests.

It should also be noted that in-use locomotives are rarely operated continuously

in a single notch for longer than these minimum sampling periods, especially for the

intermediate power notches (1 through 7). Significant continuous operation for longer

periods only occurs for idle, dynamic brake, and notch 8, but still accounts for less than

a third of all operation. Such operation should not have any adverse environmental
78

impact because the regulations prohibit any changes in the engine calibration after the

sampling period that would increase emissions. It should also be noted that total mass

emission rates (g/hr) for idle and dynamic brake are relatively low, and that long

periods of continuous operation in dynamic brake and notch 8 are likely to be in rural

areas. Both of these factors further minimize any potential for adverse environmental

impacts from such operation. 

In the event of test equipment failure during data acquisition, testing may be

resumed by repeating the voided test mode, provided the engine is at normal operating

temperature. EPA is allowing three approaches for ensuring that the engine is at

normal operating temperatures. In the first approach, when a test mode is voided, the

engine is returned to the next lower notch position (e.g., notch 3, if the notch 4 test

mode is voided), and kept running in that notch until the problem is corrected. In the

second approach, the engine is returned to idle while the problem is corrected, then the

two test modes prior to the voided mode are repeated. With either approach, the

sequence is then continued, starting with the voided test mode. The third approach is

simply to start the test sequence over.

In order to minimize the testing burden, EPA is requiring that locomotives

equipped with dynamic brake (DB) only be tested in one DB position. The DB position

to be tested would be the notch generating nearest to 75 percent of the maximum

braking capacity. This is the DB notch that EPA expects will be most environmentally

important. While other DB positions would not have to be tested in the same manner,

they would have to incorporate the same emission controls (see "Defeat Devices"

section). Given that periods of dynamic brake use are limited, especially in urban

areas, the potential for adverse environmental impacts from this approach is fairly

minimal.

Similarly, for passenger locomotives that generate hotel power from the main

propulsion engine, EPA is not requiring that testing for compliance be conducted with

the engine producing hotel power. However, manufacturers and remanufacturers

would be required to incorporate similar emission controls for hotel mode, especially

in the area of injection timing (see "Defeat Devices" section). The Agency also retains

the authority to require emission data collection from the locomotive or engine when

it is generating hotel power.
79

Alternate Locomotive Configurations

The Agency recognizes that the potential exists for future locomotives to include

additional power notches, or even continuously variable throttles, and is creating

alternate testing requirements for such locomotives. Using the standard FTP sequence

for such locomotives would result in an emissions measurement that does not

accurately reflect their in-use emissions performance. Instead locomotives having

additional notches would be tested at each notch, and the mass emission rates for the

additional notches would be averaged with the nearest "standard" notch.

Locomotives having continuously variable throttles would be tested at idle,

dynamic brake, and 15 power levels assigned by the Administrator (including full

power), with average emission rates for two power levels (excluding full power)

assigned to the nearest "standard" notch. The 15 power levels assigned represent one

level for full power and two, to be averaged, for each of the seven intermediate power

levels used on current locomotives. The Administrator retains the authority to

prescribe other procedures for alternate throttle/power configurations.

Information provided to EPA by manufacturers on engine power levels in the

various notch positions showed that the power in propulsion notches 1 through 8

followed a similar pattern when expressed as a percentage of the rated power of the

engine. These power levels, which are shown in Table 5-2 below, would be used to

adapt the normal duty-cycle weightings. As an example, for a locomotive equipped

with 9 power notches (4, 11, 23, 35, 48, 64, 80, 90, and 100 percent of rated power),

emissions measured from notches 1 through 6 would be weighted in the usual manner,

notches 7 and 8 (80 and 90 percent of rated power) would be averaged and weighted

by the normal notch 7 weighting factor, and notch 9 (100 percent of rated power) would

be weighted by the normal notch 8 weighting factor.

Table 5-2

Typical Power Distribution by Notch

Throttle Notch 12345678

Percent of

Rated Power 4.5 11.5 23.5 35.0 48.5 64.0 85.0 100
80

5.3 Sampling and Analysis

Gaseous Sampling and Analysis

Gaseous exhaust pollutants (HC, CO , CO, and NOx) are measured by drawing 2

samples of the raw exhaust directly to chemical analyzers (with appropriate filtering).

The sample is generally drawn through these analyzers using pumps that are located

downstream of the analyzer. The sampling procedures are based on EPA's previous

experience sampling diesel exhaust from on-highway heavy-duty engines (40 CFR 86).

The required analyzers are: a chemiluminescence analyzer for NOx, a heated flame

ionization detector (HFID) for HC, and a nondispersive infrared (NDIR) detector for

CO and CO .2

Testing of current locomotives has shown that exhaust concentrations generally

reach their steady-state levels shortly after a notch change. Thus, EPA is requiring

that a single steady-state concentration be used for gaseous emissions calculations, for

each mode and each pollutant. EPA has created special provisions for locomotives that

have long stabilization periods, which could require integration of the concentration

in some cases. These provisions are criteria that specify when a steady-state emission

measurement is considered to be representative of the typical period in notch. The

criteria were developed so that a single steady-state value would be allowed for each

mode for locomotives that reach their steady-state emission levels as soon after a notch

change as most current locomotives do.

In order to ensure good reliability of test results, EPA is also establishing

calibration and verification requirements similar to those applicable to on-highway

heavy-duty engines. However, in these regulations, unlike the regulations for highway

engines, the Agency is not establishing dilute sampling procedures for the total

exhaust stream for gaseous emissions because it is not necessary to dilute the total

exhaust stream prior to sampling with steady-state operation. In addition, the

equipment that is required for dilute sampling would be very large and expensive.

Nevertheless, not including such provisions does not preclude the use of dilute

sampling as an alternative procedure.

Particulate Sampling and Analysis

Particulates are measured by drawing a sample of the exhaust through a filter

and weighing the mass of particulate collected. Particulate sampling requires dilution

of the sample to lower the temperature below 125°F, which minimizes evaporation of

volatile particulate matter from the filters. The particulate sampling procedures are

also based on the procedures found in 40 CFR 86. However, since the locomotive test

cycle is essentially steady-state (and thus the volumetric flow rate of the exhaust is

essentially constant for each test mode), the dilution and sampling systems can be

simpler than are required for on-highway engine testing. The regulations do not
 Guerrieri, D., V. Rao, and P. Caffrey, "An investigation of the Effect of Differing 72

Filter Face Velocities on Particulate Mass Weight from Heavy-duty Diesel Engines," SAE

Paper No. 960253, February 1996.

81

require any critical flow venturi, or heat exchangers, since these are only used to

maintain proportional sampling when the exhaust volumetric flow rate is changing

continuously.

The regulations include specific requirements for the weighing of particulate

filters. These requirements are intended to minimize contamination of the filters by

dust or water vapor, which could otherwise lead to significant inaccuracy in the

measurement. Also included in the regulations are recommended target loadings to

ensure that sufficient particulate mass is collected to allow a meaningful

measurement. Finally, the regulations include limits on the range of acceptable filter

face velocities (i.e., the volumetric sample flow rate divided by the cross-sectional area

of the filter) based on testing of on-highway engines and industry comments. 72

Exhaust Ducting and Sample Probes

During locomotive testing, the exhaust emissions are routed through a metal duct,

or exhaust stack extension, which is located directly over the exhaust outlet of the

locomotive. It is important that the duct design is sufficiently open so that it does not

cause any significant increase in the exhaust back pressure in the engine. The purpose

of this duct is to prevent disturbance or dilution of the exhaust plume during sampling,

and to provide for standardization of the sample probe location. The regulations call

for the sample probes to be located in the duct between 2 and 5 feet downstream of the

exhaust outlet during locomotive testing, or the nearest practical equivalent during

engine testing. Although sample probe is not expected to have a large impact on

repeatability, this specification is appropriate since it does not represent a significant

burden. The allowance for different sample probe locations during engine testing is a

recognition that issues such as safety or accessibility of the probes in engine test

facilities may require that the probes be located more than 20 feet downstream of the

exhaust outlet.

When testing locomotive engines with more than one exhaust outlet, the

regulations require that all exhaust outlets be ducted together prior to sampling.

However, for locomotive testing, it is not necessary to duct the exhaust outlets

together, provided that a proportional sample is collected from each outlet, and a check

is performed to ensure that the exhaust flows from each outlet are similar. More

specifically, the regulations require that CO concentrations be measured from each 2

outlet, and that they be within 5 percent of each other. EPA believes that similar CO2

concentrations are a reasonable indication that the exhaust flows are similar.

Assuming that an engine was designed to have similar exhaust flows for each outlet,

then the types of malfunction that would cause dissimilar flows should also cause
Nn

'100×1& 1& Nm

100

1/L

82

dissimilar CO concentrations. For example, malfunctions that caused a loss of power 2

in a given cylinder will typically lead to an increase in fuel consumption, as the engine

controls increase the fueling rate in an attempt to maintain the power output. Such

malfunctions would thus change the air/fuel ratio and should result in increased CO2

concentrations for the exhaust outlet of the malfunctioning cylinder.

The three sample probe designs specified in the regulations are intended to collect

a representative sample during testing. The basic designs have been successfully used

previously for testing other diesel engines. The gaseous sample probe design is the

same as is specified for general nonroad engine testing in 40 CFR 89. The dilute

particulate probe design is the same as the design used for on-highway engine testing

(40 CFR 86). The raw particulate probe design was used previously for diesel engine

testing at SwRI. All three specific designs were tested for EPA at SwRI, and shown to

work very well for locomotive emission testing.

Smoke Measurement

Smoke is measured with a smoke opacity meter mounted on top of the exhaust

stack extension. The instrument specifications are the same as those used for onhighway heavy-duty engines. The meter measures opacity of the exhaust across the

longest (nondiagonal) dimension of the extension. Emission measurements are

normalized, using the following equation, to be equivalent to measurements made with

an instrument that had a one-meter long (3.281 feet) path length. This equation is

derived from the Beer-Lambert law that states that the logarithm of the transmissivity

of a gas (i.e., one minus the opacity) is proportional to the path length.

Where N is the normalized percent opacity, N is the measured percent opacity, and n m

L is actual path length of the measurement system in meters (only that portion of the

optical path that actually passes through the plume). 

For simplicity, EPA has also included, as an appendix to the regulations, a table

which allows an approximate comparison of measured smoke levels directly to the

standard without normalization. This table shows comparable smoke standards for

various path lengths in 10-centimeter increments. The comparable smoke standards

were calculated from the low end of each range (e.g., 70.0 cm for the 70.0-79.9cm

range), so that use of these standards for non-normalized measurements would not be

less stringent than the official standard for normalized measurements.
83

Power and Fuel Measurement

Brake horsepower is the sum of the horsepower supplied to the main alternator

and the mechanical horsepower required to operate accessories such as a secondary

alternator. Power required to operate oil and fuel pumps, or to circulate coolant for the

engine are not included in brake horsepower. The horsepower supplied to the main

alternator is calculated as the product of the output voltage and current, divided by the

alternator efficiency. The output voltage and current are measured directly using a

voltmeter and current shunt. The alternator output may also be read from an onboard

measurement system, provided that it meets the accuracy and precision requirements

specified in the regulations. The alternator efficiency and accessory loads do not need

to be measured during testing, provided that this information is supplied by the

manufacturer or remanufacturer. The alternator efficiency must be expressed as a

function of power input. The effect of temperature on the alternator efficiency must

also be taken into account, where possible.

Fuel flow rates are determined by measuring the change in mass of an external

fuel supply tank. For locomotive testing, the fuel intake and recycle lines are

disconnected from the locomotive fuel tank and connected to the external tank. For

many systems, a heat exchanger will be necessary to dissipate the heat from the

recycled fuel. It is important to maintain a relatively constant fuel temperature, in

order to obtain a stable measurement of the mass of fuel in the tank. Also, given

currently available technology, a one-minute averaging period is recommended in order

to obtain an accurate fuel flow rate measurement for all notches except idle, where a

three-minute averaging period is recommended.

Natural Gas-Fueled and Alcohol-Fueled Engines

EPA is currently aware of only a few natural gas-fueled locomotives, and is not

aware of any alcohol-fueled locomotives. Nevertheless, EPA believes that it is

appropriate to include test procedures for such locomotives in these regulations. For

this reason, the NMHC, alcohol and aldehyde measurement procedures that are

currently applicable to on-highway natural gas- and methanol-fueled engines (40 CFR

part 86) are being used for natural gas- and alcohol-fueled locomotives. EPA

recognizes, however, the possibility of unforeseen problems that could result during the

use of such procedures with locomotive engines, especially with alcohol-fueled

locomotives (which currently do not exist). There is a lack of information on whether

the specifications for dilute alcohol and aldehyde sample temperatures and flow rates

are appropriate for locomotives, as well as a complete lack of such specifications for raw

exhaust. Previous testing of highway vehicles has shown the potential for losses of

alcohols and aldehydes through condensation if the sample line temperature is too low,

or chemical reactions if it is too high. Nevertheless, at this time, EPA believes that it

is appropriate to specify the on-highway procedures, but may reconsider alcohol and
 Y = the water vapor concentration of the intake air expressed as a volume fraction; and 73

" = the atomic hydrogen/carbon ratio of the fuel.

 Docket item #A-94-31-IV-D-36. 74

84

aldehyde sampling issues on a case-by-case basis, should alcohol-fueled locomotives

come into use. Other aspects of the test procedure are the same as for diesel

locomotives.

Calculations

The calculations specified for raw exhaust analysis are based on those in Subpart

D of part 86. The algebraic form of some of the equations was changed slightly to

clarify their meaning. Also, equations for both wet and dry analysis are included for

each regulated species. The greatest change from the Subpart D calculations is that

the calculation of the wet-to-dry conversion factor (K ) is done in several steps, with W

iteration, instead of in a single equation. The calculation of DH2O is an algebraic

solution of a hydrogen balance around of the engine, excluding hydrogen bound to

organic matter in the exhaust. The sources of hydrogen are water entering in the

intake air (2Y•DVol ) and hydrogen released from the fuel during combustion air

(2"(DCO2+DCO)DVol, where DCO2 and DCO are volume fractions); the small 73

amount of hydrogen released from incomplete combustion reactions which do not

produce CO or CO is assumed to be negligible. The hydrogen in the exhaust is 2

assumed to be in two forms: water and elemental hydrogen (H ). The elemental 2

hydrogen is assumed to be in equilibrium with respect to the following reaction:

H + CO = H O + CO (equilibrium constant = K) 2 2 2

The calculation of DVol is an algebraic solution of a balance of the number of dry air

moles (excluding water) in the gas phase; the difference in the number of dry moles

before and after combustion, neglecting H formation and volatilization of the fuel, and 2

assuming that all NOx produced is in the form of NO, is the amount of O consumed 2

minus the amount of CO and CO produced. The calculation of DVol is an algebraic 2

solution of a carbon balance of the moles of carbon coming into the engine (W /CMW ) f f

and the moles of carbon in the exhaust (DVol•V •(DHC+DCO+DCO2), where DHC is m

the volume fraction of organic carbon (ppmC/10 ) and DCO and DCO2 are volume 6

fractions (ppm/10 )). The regulations also include an approximate non-iterative option 6

for calculating K . This option uses an approximate calculation for DH2O that was W

recommended by the Engine Manufacturers Association in its comments on the

NPRM.74

The calculations specified for dilute exhaust analysis are identical to those in

Subpart N of part 86, except that the equations for calculating the dilution factor and

the fraction of exhaust that is diluted (if partial dilution is used) are new. The dilution
 Emission Measurements, Locomotives, Southwest Research Institute Report for EPA, 75

August, 1995.

85

factor (DF) equation comes from a CO balance around the dilution tunnel, and the 2

fraction diluted (V ) equation comes from a mass balance of the carbon in the diluted f

exhaust with the carbon coming into the engine in the fuel. The dilution factor is the

ratio of the volume of dilution air to the volume of exhaust sample that is diluted. (The

ratio of the total volume of dilution air plus exhaust sample to the volume of exhaust

sample that is diluted is equal to one plus DF.)

5.4 Fuel Quality

Effects of Fuel Quality on Emissions

Changes in diesel fuel quality can have a significant effect on exhaust emissions.

Perhaps the most important fuel parameter, with respect to emissions, is the weight

fraction of sulfur in the fuel. Sulfur is a normal contaminant in crude oil and diesel

fuel that is converted primarily to sulfur dioxide during combustion. A small amount

of the sulfur, however, is converted to sulfate particulate. Thus, lowering the sulfur

content of diesel fuel can lead to lower particulate emissions. A study by SwRI showed

that lowering the sulfur content of diesel fuel from 0.315 weight percent (a typical inuse level for nonroad engine fuel) to 0.033 weight percent resulted in particulate

reductions of 0.05 to 0.08 g/bhp-hr from uncontrolled locomotives. Other studies have 75

been less conclusive. It is important to note that, while the effect of sulfur on

particulate levels is expected to vary from engine to engine because of different

combustion properties, it should be relatively independent of total particulate levels.

This is because sulfate particulate results from the oxidation of the fuel sulfur, rather

than from incomplete combustion, which is the cause of organic particulates. It is

known that railroads do occasionally purchase low-sulfur diesel for use in their

locomotives, however, EPA is not aware of any reliable data regarding the relative

amounts of high-sulfur and low-sulfur fuel used by the railroad industry. It is probable

that the nationwide fraction of total fuel use that is low-sulfur is on the order of ten

percent. 

There are few data available on the effects of other fuel parameters on emissions

from locomotives. However, data collected from on-highway heavy-duty emission

testing have shown that increasing cetane number and decreasing aromatics content

contribute to somewhat lower NOx and PM emissions. A combined reduction in

aromatics content as well as an increase in cetane number was seen to give additional

benefits in the reduction of NOx and PM.
86

Test Fuel Specifications

The Agency is establishing test fuel specifications for compliance testing

(certification, PLT and manufacturer/remanufacturer in-use testing) which are

intended to be representative of in-use nonroad diesel fuel. More specifically, they are

consistent with test fuel specifications for on-highway heavy-duty engine certification

testing, with the exception of the sulfur specification. EPA is establishing a lower

sulfur limit of 0.2 weight percent. The cetane and aromatics requirements are a cetane

number of 40 to 48 and an aromatics content of at least 27 percent. These

specifications are intended to approximate reasonable, but somewhat worst case in-use

conditions. Since EPA is not regulating in-use fuel quality for locomotives, there is no

reason to believe that in-use locomotives will use only low sulfur on-highway fuel,

especially given the potential price differences between low and high sulfur diesel

fuels, and potential availability problems in some areas of the country. Should EPA

regulate in-use locomotive fuels in the future, it would also adjust the test fuel

specifications as appropriate. It should be noted that any improvements in in-use fuel

quality would also necessitate a reconsideration of the appropriate levels of the

standards.

5.6 Atmospheric Conditions During Testing

As is described in Chapter 3, ambient conditions such as temperature, humidity,

and barometric pressure are known to affect emissions from diesel engines. These test

conditions need to be limited to some extent to keep the compliance burden for

manufacturers and remanufacturers reasonable. However, in order to ensure that

these regulations achieve the expected environmental benefits during normal railroad

operations, and to allow for outdoor testing, EPA is specifying a fairly wide range of

temperatures and pressures for testing, with no restrictions on humidity. The specified

range of test conditions is an attempt to balance the environmental needs with those

of the manufacturers and remanufacturers. An important factor which supports the

wide range is that the large size of locomotives makes outdoor testing desirable. While

indoor testing of a locomotive engine under controlled temperature conditions could

reasonably be expected to be practical, testing of a complete locomotive indoors would

be more costly and may prove to be very difficult to implement in many cases.
87

Specifically, EPA is establishing a range for the test temperature of 45-105EF.

The upper limit temperature of 105EF is specified to address summer high

temperatures throughout the southern and western areas of the country, and to

facilitate testing of locomotives under most conditions which can occur over much of

the nation during the summer. By choosing this upper limit for the test temperature,

EPA expects to also address any potential loss in control of NOx emissions, and even

PM and smoke, if charge air density decreases sufficiently at very high ambient

temperatures. There is a potential for NOx emissions to increase at very high

temperatures if the effectiveness of charge air cooling decreases at these high

temperatures.

The lower limit for the test temperature (45EF) was based on: 1) the prevailing

temperatures in the areas of the nation where locomotives are manufactured and

remanufactured (e.g., Pennsylvania, Illinois and Idaho), 2) the fact that ozone pollution

is essentially a warm weather problem, and 3) the potential test variability that could

occur at lower temperatures. Under low ambient temperatures, the effectiveness of

charge air cooling as a NOx control strategy can be expected to increase, especially if

engine coolant is not used as the cooling medium. At the same time, some increase in

PM and smoke emissions can be expected if excessive cooling of the charge air is

allowed to occur. This lower limit should allow outdoor testing during much of the

year, without unreasonable test variability problems. Acquisition of test data when

prevailing ambient temperatures at manufacturers' or remanufacturers' facilities are

below the lower test limit can be achieved by providing indoor facilities. EPA could

also allow testing at lower temperatures, but only in cases where a manufacturer or

remanufacturer can demonstrate that it would not result in any compliance advantage.

EPA also sees the need to include compliance with the standards up to 7000 feet

above sea level to achieve control of locomotive emissions at high altitude. This is

necessary because some emission control technologies suitable for the control of NOx

emissions, e.g., delaying the start of fuel injection, will tend to exacerbate other

emissions, e.g., PM and smoke, especially at high altitudes. The inclusion of

equipment that would assure the same absolute pressure of the charge air in the

intake manifold at both low and high altitudes would reduce or control this concern.

However, there is a significant burden associated with testing over a very wide range

of barometric pressures to demonstrate compliance, which EPA believes should be

limited. Therefore, EPA is establishing a lower limit on ambient pressure of 26 inches

of mercury for testing. This corresponds to an elevation of about 4000 feet above sea

level. EPA is requiring compliance at higher elevations, but is only requiring an

engineering analysis to demonstrate the performance of the locomotive emission

controls at elevations between 4000 and 7000 feet (about 23 inches of mercury).
KH'

C1%C2e (&0.0143)(10.714)

C1%C2e (&0.0143)(1000H)

KT' 1

1&0.017(T30&TA)

 Docket item #A-94-31-IV-A-2. 76

88

In the proposal, the Agency recognized the need to correct NOx emissions for the

effects of humidity and temperature during testing, but it did not propose specific

correction factors. EPA considered using the NOx-humidity correction factor that is

currently being used for on-highway and general nonroad diesel engines (40 CFR 86

and 89), but concluded that the data upon which that correction factor was based are

not adequate for this rulemaking. In particular, EPA had concerns about the

applicability of data from older pre-control on-highway engines to current and future

locomotives that incorporate NOx-reduction technologies. More importantly, however,

the data are inappropriate as a basis for such correction factors for locomotives because

the range of test conditions for locomotives being established is much broader than was

used in the collection of that data. Therefore, EPA contracted with SwRI to provide an

analysis that would support the development of locomotive specific correction factors.

The contractor provided a partial analysis, which EPA used for this rulemaking, but

was not able to complete the analysis before the rule was finalized. This partial

analysis can be found in the docket.76

That analysis recommended the following correction factors for the effects of

ambient humidity and temperature:

Where:

C = -8.7 +164.5e 1

-0.0218(A/F)

C = 130.7 +3941e 2

-0.0248(A/F)

H = The specific humidity on a dry basis of the intake air (grams of water per kilogram of dry

air).

(A/F) = Mass of moist air intake divided by mass of fuel intake.

T = The measured intake manifold air temperature in the locomotive when operated at 30°C. 30

T = The measured intake manifold air temperature in the locomotive as tested. A

It is important to note that the correction factor for temperature actually uses the

intake air temperature rather than the ambient temperature. This is because it is the

effect of ambient temperature on the intake air that matters most, but this effect is

highly variable from locomotive to locomotive. EPA is not allowing correction for the
F ' 1% 0.25(log(KTKH )

2 )

KNOx' (F)(KT )(KH )

89

effects of ambient temperatures above 86°F. For most current locomotives, ambient

temperature does not significantly affect intake air temperature over a broad range of

ambient temperatures. This may not continue to be true for future locomotives, and

EPA does want to provide an adjustment that would "correct" for a poorly designed

aftercooler system. Finally, EPA recognizes that changes in ambient temperature can

have other effects on measured emission rates (other than the effect of intake air

temperature), but does not have any information on the effects at this time.

Since the effects of humidity and temperature on NOx emissions from locomotives

are not fully understood at this time, EPA has decided to include conservative default

correction factors in the final rule (i.e., factors that are more likely to overestimate

emissions rather than underestimate emissions), but to allow manufacturers and

remanufacturers to use their own correction factors where they are appropriate for

their specific locomotives. The correction factor being used in the final regulations

(K ) is the product of the temperature and humidity correction factors developed by NOx

the contractor (K T • K ) multiplied by an adjustment factor (F) to address uncertainty H

in the estimated correction. The adjustment is defined as:

Thus, the final correction factor is calculated as:

The effect of this uncertainty factor is shown in Table 5-3. As can be seen from the

table, the uncertainty factor is always greater than one, and becomes smaller as the

correction factor becomes closer to 1.000. Thus, this factor appropriately accounts for

the uncertainty in the correction, which is least for those test conditions which are

closest to 86°F and 75 grains (or 10.71 g of moisture per kg of dry air).
90

Table 5-3

Adjustment to Correction Factors

(K )(K ) Uncertainty Factor K T H NOx

0.800 1.048 0.839

0.900 1.023 0.921

0.950 1.011 0.961

0.985 1.003 0.988

1.000 1.000 1.000

1.030 1.006 1.037

1.050 1.011 1.061

1.100 1.021 1.123

1.200 1.040 1.248

The Agency recognizes that the correction factors being established in these

regulations may not be appropriate for the long term, but believes that they are

appropriate at this time. During the first several years of this program, EPA expects

that nearly all manufacturers and remanufacturers will perform engine testing rather

than locomotive testing, and will therefore be able to perform all testing under

controlled conditions where the effect of the correction factors will be small (i.e. near

86°F and 75 grains). Moreover, where the manufacturer or remanufacturer believes

that the default correction factors penalize them, they will be able to develop and use

their own correction factors. Nevertheless, EPA expects to refine these correction

factors in the future when better information becomes available.

5.7 Other Issues

Defeat Devices

A defeat device is a device or element of design that reduces the effectiveness of

emissions control during actual operation, but that does not significantly affect

emissions control under test conditions, or affects it to a significantly lesser degree.

Such devices are prohibited by the Clean Air Act. The procedures and penalties for a

finding of a violation of the defeat device prohibition are detailed in the regulations.

Penalties for a violation could be as much as $25,000 per locomotive per day. EPA

recognizes a significant potential for the use of defeat devices in locomotives, especially

those equipped with electronic engine controls. Some examples are described below.

The simplest example of a defeat device would be an electronically controlled

engine that had two injection timing calibrations: a low emission calibration (e.g.,

retarded timing) that is used during testing, and a low fuel consumption calibration
91

(e.g., advanced timing) that is used all other times. Such a device could easily

recognize that a locomotive was being tested because there would be no power going

to the traction motors.

A second potential defeat device would be a calibration that had high emissions

just after a notch change, but had much lower emissions near the end of the test mode

(e.g., five minutes after the notch change). This would allow the locomotive to be

calibrated for low fuel consumption during the first few minutes, but still have a

"steady-state" emission level that is reasonably low. This is significant because the sixminute sampling period required by this regulation is significantly longer than the

typical time in the intermediate power notches in actual use. Thus, a locomotive could

be operated in a high-emission/low-fuel consumption mode the majority of the time in

use, and spend relatively little time in the low-emission mode. This issue is addressed

to some extent by the steady-state stability criteria included in the test procedure

regulations. Similarly, a calibration that advanced timing after the end of the

sampling period would also be considered to be a defeat device.

It should be noted that EPA does recognize that, to a limited extent,

manufacturers can have legitimate reasons for calibrations that change with time.

Most notably, it is often necessary to increase the fueling rate slowly after a notch

change in order to prevent smoke emissions. In these cases, the variability of the

calibration generally lasts only a few seconds, and should not adversely affect any

emissions. EPA would not consider such a calibration to be a defeat device, provided

that the manufacturer could provide adequate technical justification at the time of

certification.

A more subtle form of defeat device would be a calibration that varied significantly

by notch to the extent that it would influence the operation of the locomotive,

discouraging the use of certain notches. EPA believes that if a locomotive was

calibrated with severely retarded timing in one notch, operators may rarely use that

notch because of concerns about fuel consumption or power output. As with the

previous example, EPA would consider such a calibration to be a defeat device, unless

the manufacturer provided adequate technical justification for the calibration.

Passenger locomotives designed to provide hotel power from the traction engine

create the potential for a defeat device because the engine can be operated in an

infinitely variable mode, depending on the hotel power load being placed on the engine.

Such an engine could be calibrated to have low emissions when generating no hotel

power (i.e., the test condition), but have higher emissions whenever it generates hotel

power. Such calibration would clearly be a defeat device.

If a locomotive engine was never subject to testing in the locomotive chassis, it is

possible that the engine could be tested at slightly different conditions (e.g., fueling

rate or load) than those at which it would be operated in use, and thus could have a
92

completely different calibration and emission performance. This is one of the reasons

why EPA believes that it is necessary that every engine model be subject to in-use

chassis testing.

Finally, unnecessary loading of the engine at idle and during dynamic brake

operations by means such as operation of cooling fans, etc., when not required for the

proper operation of the engine or locomotive, would also be considered to be a defeat

device. EPA expects that any loads imposed during testing will also generally be

imposed during actual locomotive operations. By requiring that any such load be

imposed in use, it is expected that concerns about maximizing fuel efficiency will

curtail any unnecessary loading of the engine during testing.

Idle Shutdown

The Agency is finalizing a regulatory incentive for the development of an

automatic shutdown mechanism that could shut off an engine automatically after some

extended period of idling. (Current locomotive engines tend not to be shut down for

long periods of time, especially in cold weather, because it can be difficult to start these

engines if they are allowed to cool to relatively low ambient temperatures and because

of the potential for engine damage due to leakage of coolant.) The approach would be

to reduce the weighting factor for the idle emission rate for engines equipped with

automatic shutdown mechanisms, but use the higher power weighting factor that is

specified in the regulations. This approach would account for the emissions benefits

of a shutdown mechanism whereas the standard calculations would not.

At this time, EPA is not establishing specific alternate weighting factors for these

locomotives because it does not have adequate information to accurately predict how

much idling time would be reduced by such a feature. The Agency expects that an

automatic shutdown would not have much of an impact on idling time for newer linehaul locomotives because they rarely are left at idle for long periods of time. However,

an automatic shutdown mechanism may have a very significant impact on idling time

for switch locomotives. Nevertheless, even for switch locomotives, the impact is hard

to predict at this time. The impact would be greater for locomotives that shutdown

after a shorter period of time, or for applications in which long idling periods are more

common. Thus, EPA will require that any manufacturer or remanufacturer desiring

credit for an automatic shutdown mechanism demonstrate the average percent

reduction of idling time that it would achieve.

This option is expected to be especially useful for compliance with the switch-cycle

standards because the high idle weighting factor in the switch cycle (0.598) will put

significant pressure on manufacturers and remanufacturers to reduce idling emissions.

With this option, a manufacturer or remanufacturer would get the same credit for

reducing the idle emission rate (g/hr) by half as it would for reducing idling time by

half. For example, consider two locomotives: 1) a locomotive with an idle emission rate
 Docket item #A-94-31-IV-D-36. 77

93

of 350 g/hr; and 2) a locomotive with an idle emission rate of 700 g/hr, but with an

automatic shutdown mechanism that was shown to reduce idling time by half.

Assuming that power output rates at all notches are the same, and that emission rates

for all non-idle notches are the same, then the two locomotives would have the same

calculated cycle-weighted emission rates. This is because the contribution of idle

emissions to the cycle-weighted total would be 209 g/hr in both cases; (350)X(0.598) in

the first case, and (700)X(0.598)X(0.5) in the second case. (Note: the weighting factor

for the power output would be 0.598 in both cases.) The two cases would also be

equivalent from an environmental perspective.

Correlation Criteria for Alternate Measurement Systems

EPA has included as an appendix to the regulations a set of recommended criteria

for demonstrating equivalence of alternate measurement systems. The criteria specify

the appropriate test procedures, number of replicate tests, and degree of correlation.

These criteria are based on recommendations made by the Engine Manufacturers

Association (EMA) in their comments on the NPRM. The final criteria differ from 77

EMA's criteria in that they allow less variation for systems that measure low (while

EMA allowed 5 percent variation for both high and low measurements), and they

include specific requirements for replicating outliers. It is important to note that these

criteria are merely recommendations. Manufacturers are allowed to submit for EPA

approval other types of data which they believe demonstrate equivalence. These

recommendations, however, provide the manufacturers more certainty regarding the

type of data that EPA will normally expect.
 The results described in this chapter are identical to those found in the December 1997 78

version of this document, including several minor errors. Results of corrected analyses are

contained in Appendix O.

 This conversion factor was calculated from data in the SwRI report. It thus represents 79

the conversion factor for locomotives manufactured in the mid-1990s. Older locomotives

would be expected to produce less useful work from each gallon of fuel (i.e., have a smaller

conversion factor), while future locomotives are likely to produce more work from each

gallon of fuel (i.e., have a larger conversion factor).

94

6.0 Emission Benefits

This section discusses the emission benefits expected from this rulemaking.78

Emission benefits are presented both in terms of percent reductions and tons of

pollutants reduced annually. This analysis separately addresses the impacts of:

1) Class I (freight-only) line-haul locomotives

2) Class I (freight-only) switch locomotives

3) Class II and III locomotives

4) Passenger locomotives

Emission benefits were calculated in the following manner. First, as described in

Chapter 4, controlled and uncontrolled emission rates for in-use locomotives were

estimated. Average in-use emission factors were estimated by assuming purchase,

scrappage, and remanufacturing behavior for each type of locomotive service. National

emission inventories (tons per year) were calculated from the emission factors and fuel

consumption data. Reductions were calculated from a projected 1999 baseline. It is

important to note that locomotive use, purchase, scrappage, and remanufacturing

schedules vary from railroad to railroad, and that they are all relatively sensitive to

economic conditions. Therefore, this analysis, which is based on typical historical

behavior, merely represents the Agency's best estimate of impacts given the

information available at the time of the analysis.

6.1 Methodology

National emission inventories were calculated for each type of locomotive service

by first multiplying the fuel consumption rates (gal/yr) by a conversion factor of 20.8

bhp-hr/gal to obtain total fleet bhp-hr/yr values. These fleet bhp-hr/yr numbers were 79

then multiplied by the applicable fleet average emission rates to calculate emissions

inventories (tons/yr). The fleet average emission rates for each year were calculated

based on the number of each type of locomotive projected to be in the fleet at the end

of the respective year. The total reductions expected for each future year were
RelativeFuelConsumption' Nloc HP

avg

FRU

j Nloc HP

avg

FRU

95

calculated by subtracting the expected controlled inventory from the estimated 1999

baseline inventory. Locomotive emissions and their contribution to the national

inventories are shown in Appendix N. Based on the fuel consumption data shown in

Chapter 1, EPA is assuming no growth in locomotive emissions after 1996.

Fleet average emission rates were calculated as weighted averages of

uncontrolled, Tier 0, Tier 1, and Tier 2 emission rates. These emission rates were

weighted by estimated relative classwide fuel consumption rates (e.g., the percent of

total fuel consumed by Tier 1 locomotives in a given year). The relative fuel

consumption rates for each class were calculated assuming that they were proportional

to the product of number of locomotives(N ), average horsepower (HP ), and a loc avg

relative use rate factor (F ) based on average locomotive age, as shown below. RU

This part of the analysis was simplified for all locomotives other than Class I line-haul

freight locomotives (i.e., switch, Class II/III, and passenger locomotives) by neglecting

differences in average horsepower and relative use rates. This was done due to a lack

of specific information for these classes. Emissions factors were weighted by only

numbers of locomotives. This simplification does not significantly affect the overall

analysis because the differences in locomotive horsepower and usage rates for these

classes, as a function of the tier of applicable standards, are less significant than for

Class I freight locomotives. Moreover, these locomotives are relatively minor

contributors to the total national emission inventories.

The average baseline emission rates described in Chapter 4 were used for all

future uncontrolled emission rates. EPA estimated average in-use emission rates for

future controlled locomotives by subtracting a compliance margin from the level of each

of the standards. However, because the standards for HC, CO, and PM emissions from

Tier 0 and Tier 1 locomotives were set to prevent significant increases in these

pollutants, rather than to require reductions, EPA used the baseline emission rates in

the cases where the standards would not force emission reductions.
 Official Locomotive Rosters and News, 1997 special edition-Class I railroads, James 80

W. Kerr, July 31, 1997.

96

TABLE 6-1

Estimated Emission Rates for Class I Locomotives (g/bhp-hr)

Line-Haul Switch

Locomotives Locomotives

HC

Uncontrolled 0.48 1.01

Tier 0 0.48 1.01

Tier I 0.47 1.01

Tier II 0.26 0.51

CO

Uncontrolled 1.28 1.83

Tier 0 1.28 1.83

Tier I 1.28 1.83

Tier II 1.28 1.83

NOx

Uncontrolled 13.0 17.4

Tier 0 8.6 12.6

Tier I 6.7 9.9

Tier II 5.0 7.3

PM

Uncontrolled 0.32 0.44

Tier 0 0.32 0.44

Tier I 0.32 0.43

Tier II 0.16 0.19

6.2 Class I Railroad Analysis

Assumptions

There are currently about 21,000 Class I locomotives being operated in the United

States. (AAR believes that this estimate is high; they estimate that there are less 80

than 20,000 locomotives actively being operated currently.) About 17,500 of these

locomotives were originally manufactured after 1972, and are thus subject to these
 "Railroad Facts", Association of American Railroads, 1997 edition. 81

 "Railroad Ten Year Trends," Association of American Railroads, 1995. 82

97

regulations. These locomotives are used primarily in line-haul service. Most of the

roughly 3,500 older locomotives are used as switchers. Based on these numbers, EPA

is projecting that, in 1999, Class I railroads will have about 15,200 post-1972

locomotives, and 1,300 older locomotives in line-haul service. EPA is also projecting

that they will have about 2,500 post-1972 locomotives, and 2,000 older locomotives in

switch service. It is assumed that by 2008 (i.e., within six years of the time that this

rule takes full effect), nearly all 1973 through 1999 line-haul locomotives will have

been remanufactured to meet EPA's standards for these locomotives and locomotive

engines.

More specifically, EPA is assuming that 13,200 of the post-1972 line-haul

locomotives will be brought into compliance with the Tier 0 standards by 2008, and

that 2,000 post-1972 locomotives and all 1,000 older line-haul locomotives will have

been removed from Class I line-haul service by 2010. EPA is also assuming that 3,000

Class I switch locomotives will be brought into compliance by 2017, including many

older locomotives that will be repowered or upgraded, and that the remainder of the

existing Class I switch fleet will have been removed from Class I service by 2024.

EPA is assuming that fuel consumption will remain constant at the 1996 level of

3.601 billion gallons per year. EPA recognizes that there is a short-term trend of 81

increasing fuel consumption, but is not confident that it will continue. The long-term

trend is for fuel consumption to remain fairly constant. This is the result of continual

improvements in locomotive fuel economy, which have offset the significant increase

in ton-miles of freight hauled. EPA is also assuming that 7.5 percent of fuel

consumption by Class I railroads is for switching.82

With respect to new production of freshly manufactured line-haul locomotives,

EPA is assuming 400 new units for years 2000-2004, 600 new units for years 2005-

2010, and 300 new units for all subsequent years. The higher number assumed for

years 2005-2010, is because the two largest western railroads are expected to purchase

large numbers of Tier 2 locomotives during this period in order to accelerate their

introduction into Southern California. After this period, sales are expected to slow

somewhat in terms of number of units due to the higher horsepower output of each

locomotive. EPA is also projecting that switcher sales will range from 50 to 100 per

year.
 The results shown in this table are the same as those found in the December 1997 83

version of this document. Results of corrected analyses are contained in Appendix O.

98

Results

The results of the Class I emission analysis are summarized in Tables 6-2 (linehaul) and 6-3 (switch). More detailed results are shown in Appendix I. These results

project a 44 percent reduction in NOx emissions from line-haul locomotives by 2010.

Figure 6-1 shows those NOx emission reductions expected in the first ten years from

each tier of locomotive. As can be seen in the figure, the majority of emission

reductions during the first ten years of the program come from Tier 0 locomotives.

Emissions from switch locomotives are not expected to decrease as rapidly as emissions

from line-haul locomotives because of a slower fleet turnover rate to Tier 2 technology.

(Although not shown in the figure, emission reductions from Class I switch locomotives

are distributed similarly with respect to locomotive tier.) Significant reductions in HC

and PM emissions are not expected until Tier 2 locomotives are phased into the fleet

in large numbers.

 Table 6-2

Results of Class I Line-Haul Emission Analysis83

Emission Reductions

(Metric Tons/Year) (Metric Tons/Year) Percent Reduction

Year HC NOx PM HC NOx PM HC NOx PM

1999 33,300 901,000 22,200 0 0 0 0% 0% 0%

2000 33,300 889,000 22,200 0 11,000 0 0% 1% 0%

2005 31,900 614,000 21,300 1,400 287,000 900 4% 32% 4%

2010 27,300 485,000 18,000 5,900 415,000 4,100 18% 46% 19%

2015 25,200 453,000 16,500 8,000 448,000 5,600 24% 50% 25%

2020 23,300 423,000 15,100 10,000 478,000 7,000 30% 53% 32%

2025 21,500 395,000 13,800 11,800 506,000 8,300 35% 56% 38%

2030 19,900 370,000 12,700 13,400 531,000 9,500 40% 59% 43%

2035 18,600 350,000 11,700 14,700 551,000 10,400 44% 61% 47%

2040 17,900 345,000 11,300 15,300 556,000 10,900 46% 62% 49%
0

100

200

300

400

500

2000 2005 2010

Tier 0

Tier 1

Tier 2

Figure 6-1

Class I Line-Haul NOx Reductions by Tier of Locomotive

99

 Table 6-3

Results of Class I Switch Emission Analysis

Emission Reductions

(Metric Tons/Year) (Metric Tons/Year) Percent Reduction

Year HC NOx PM HC NOx PM HC NOx PM

1999 5,670 98,700 2,470 0 0 0 0% 0% 0%

2000 5,670 98,700 2,470 0 0 0 0% 0% 0%

2005 5,640 90,900 2,460 30 6,800 20 1% 7% 1%

2010 5,470 81,400 2,370 210 16,400 100 4% 17% 4%

2015 5,260 71,200 2,270 410 26,500 210 7% 27% 8%

2020 5,030 65,200 2,150 650 32,500 320 11% 33% 13%

2025 476 60,500 2,020 920 37,200 460 16% 38% 18%

2030 4,440 57,200 1,860 1,230 40,500 610 22% 41% 25%

2035 4,040 52,800 1,660 1,640 44,900 810 29% 46% 33%

2040 3,580 47,900 1,430 2,100 49,800 1,040 37% 51% 42%
 "Locomotive Data for Small Railroads," Memorandum, Charles Moulis, U.S. EPA, to 84

public docket A-94-31, December 5, 1997.

100

6.3 Class II and III Railroad Analysis

Assumptions

Information provided to EPA by the American Short Line Railroad Association,

which represents most of the Class II and Class III railroads, shows that there were

approximately 4,200 locomotives in service with Class II and III railroads in 1994, and

that they consumed about 215 million gallons of diesel that year. However, only 84

about 15 percent of these locomotives were originally manufactured after 1972. Based

on these numbers, EPA is projecting that there will be about 600 post-1972 locomotives

and 3600 older locomotives in the 1999 Class II and III fleet. Due to a lack of specific

information, average Class II and III emission rates are assumed to be the same as the

average emission rates for Class I line-haul locomotives. It is possible that actual

emission rates could be somewhat higher since smaller railroads typically have lower

power duty-cycles (i.e., more time at idle and low power notches, and less at notch 8),

especially those railroads performing primarily switch and terminal services.

EPA is assuming that, during the first 10 years of the program (assuming that the

remanufacture cycle for small railroads is about 10 years), Class II and III railroads

will bring about 50 locomotives per year into compliance with the Tier 0 standards in

order to have them covered as "new locomotives" by the CAA preemption provisions.

EPA is also assuming that in 2012 these railroads will begin to purchase about 150

complying Tier 0 locomotives per year from Class I railroads. It is unlikely that they

would be able to purchase any complying locomotives prior to this time. In cases where

a Class I railroad makes the investment to bring an existing locomotive into

compliance, it will almost certainly retain it for a period equivalent to two full useful

life periods. Thus, they are not likely to sell any locomotives that they have brought

into compliance until at least 12 years after they were originally brought into

compliance.

Results

The results of the Class II and III emission analysis are summarized in Table 6-4.

More detailed results are shown in Appendix I. These results show that NOx

emissions from small railroads represent only about 6 percent of all locomotive

emissions. These emissions will decrease slowly because of a fairly slow fleet turnover

rate to Tier 0 technology. The analysis projects no significant reductions in HC and

PM emissions because Tier 2 locomotives are not expected to be phased into Class II

and III fleets in large numbers in the foreseeable future.
 "1996 Transit Vehicle Fact Book", American Public Transit Association. 85

101

 Table 6-4

Results of Class II and III Emission Analysis

Emission Reductions

(Metric Tons/Year) (Metric Tons/Year) Percent Reduction

Year HC NOx PM HC NOx PM HC NOx PM

1999 2,150 58,100 1,430 0 0 0 0% 0% 0%

2000 2,150 58,100 1,430 0 0 0 0% 0% 0%

2005 2,150 57,200 1,430 0 900 0 0% 2% 0%

2010 2,150 56,000 1,430 0 2,100 0 0% 4% 0%

2015 2,150 52,900 1,430 0 5,200 0 0% 9% 0%

2020 2,150 49,400 1,430 0 8,800 0 0% 15% 0%

2025 2,150 45,800 1,430 0 12,300 0 0% 21% 0%

2030 2,150 42,300 1,430 0 15,900 0 0% 27% 0%

2035 2,150 38,700 1,430 0 19,400 0 0% 33% 0%

2040 2,150 38,200 1,430 0 19,900 0 0% 34% 0%

6.4 Passenger Railroad Analysis

Assumptions

According to the American Public Transit Association (APTA) there were

approximately 463 diesel locomotives in commuter rail service in 1995, with 397 of

these locomotives originally manufactured after 1972. These 463 locomotives

consumed about 61 million gallons of diesel fuel that year. In addition, Amtrak 85

currently has 315 diesel locomotives in service, consuming about 72 million gallons of

diesel fuel per year. EPA is projecting that 100 locomotives will be brought into

compliance during each of the first five years of the program, and that all uncontrolled

locomotives will be removed from passenger service by 2011. Sales of freshly

manufactured passenger locomotives are assumed to be 30 new units per year.

Average passenger locomotive emission rates are assumed to be the same as the

average emission rates for Class I line-haul locomotives.
 The results shown in this table are the same as those found in the December 1997 86

version of this document. Results of corrected analyses are contained in Appendix O.

102

Results

The results of the passenger locomotive emission analysis are summarized in

Table 6-5. More detailed results are shown in Appendix I. These results show that a

39 percent reduction in NOx emissions is expected by 2010. Significant reductions in

HC and PM emissions are not expected until Tier 2 locomotives are phased into the

fleet in large numbers. The rate of phase-in is expected to be roughly similar to the

rate for Class I freight service.

 Table 6-5

Results of Passenger Emission Analysis86

Emission Reductions

(Metric Tons/Year) (Metric Tons/Year) Percent Reduction

Year HC NOx PM HC NOx PM HC NOx PM

1999 1,330 36,000 890 0 0 0 0% 0% 0%

2000 1,330 36,000 890 0 0 0 0% 0% 0%

2005 1,300 26,700 870 30 9,200 20 2% 26% 2%

2010 1,180 20,900 780 150 15,100 100 11% 42% 12%

2015 1,060 18,800 700 270 17,100 190 20% 48% 21%

2020 940 16,900 610 390 19,100 270 29% 53% 31%

2025 820 15,000 530 510 21,000 360 38% 58% 40%

2030 710 13,700 440 620 22,300 440 47% 62% 50%

2035 710 13,700 440 620 22,300 440 47% 62% 50%

2040 710 13,700 440 620 22,300 440 47% 62% 50%

6.5 Summary of Environmental Benefits

Estimated emissions and emission reductions for the total U.S. locomotive fleet

are shown in Table 6-6 and Figure 6-2. The totals are dominated by the emissions and

reductions from Class I freight locomotives, which represent about 90 percent of all

current emissions from locomotives. The marginal benefits of each tier of standards,

which are used in Chapter 7 to calculate marginal cost-effectiveness, are shown in

Appendix I.
10

20

30

40

50

400

600

800

1000

1200

HC

 NOx

PM

Thousand Metric Tons per YearThousand Metric Tons per Year

HC and PM Emissions

NOx Emissions

2000 2010 2020 2030 2040

Figure 6-2 Projected Emissions

For All Freight and Passenger Locomotives

 "Benefits of Mobile Source NOx Related Particulate Matter Reductions", Final Report, 87

October 1996, Systems Applications International. Docket item #A-95-27-IV-A-01.

103

It is important to note that the NOx reductions discussed previously will also

reduce ambient PM concentrations. This is because oxides of nitrogen react in the

atmosphere to form nitrate particulate matter. It has been estimated that the

reduction in nitrate particulate matter that would result from a 100 ton NOx reduction

would be roughly equivalent to a four ton reduction in direct particulate matter.87

Thus, given the NOx and direct PM reductions shown in Table 6-6, EPA believes that

the secondary particulate reductions resulting from these regulations will be greater

than the direct particulate reductions. For example, in 2020, EPA estimates that these

regulations will result in a NOx reduction of over 530,000 metric tons per year, which

would be equivalent to a PM reduction of more than 21,000 tons per year if the

estimated four percent conversion rate is accurate. This is three times the amount of

direct PM reduction resulting from the regulations in that same year.
104

 Table 6-6

Results of Emission Analysis for All Locomotives

Emission Reductions

(Metric Tons/Year) (Metric Tons/Year) Percent Reduction

Year HC NOx PM HC NOx PM HC NOx PM

1999 42,400 1,093,000 27,000 0 0 0 0% 0% 0%

2000 42,400 1,081,000 27,000 0 11,000 0 0% 1% 0%

2005 41,000 789,000 26,000 1,400 304,000 900 3% 28% 3%

2010 36,100 644,000 22,600 6,300 449,000 4,400 15% 41% 16%

2015 33,700 596,000 20,900 8,700 496,000 6,000 21% 45% 22%

2020 31,400 554,000 19,300 11,000 538,000 7,600 26% 49% 28%

2025 29,200 516,000 17,800 13,200 576,000 9,100 31% 53% 34%

2030 27,100 483,000 16,400 15,300 610,000 10,500 36% 56% 39%

2035 25,400 456,000 15,300 17,000 637,000 11,700 40% 58% 43%

2040 24,300 445,000 14,600 18,100 648,000 12,400 43% 59% 46%

Total Reductions (2000-2040) 417,000 20,100,000 288,000
 "Cost Estimates for Meeting the Proposed Locomotive Emission Standards", Engine, 88

Fuel, and Emission Engineering, Inc., September, 1997; and "Locomotive Technologies to

Meet SOP (sic) Emission Standards", Acurex Environmental Corp., August, 1997.

105

7.0 Costs and Cost-effectiveness

Background

EPA estimated the costs of compliance with the proposed standards in the Draft

RSD, based in part on materials supplied by locomotive manufacturers and the

railroad industry. After the proposal, EPA contracted with ICF, Incorporated, with its

subcontractors, Acurex Environmental Corporation and Engine, Fuel, and Emissions

Engineering, Incorporated (EF&EE), to update the economic analysis, based on the

estimated costs for the most likely compliance technologies. In most instances, the 88

results of the cost study tended to confirm the EPA estimates, including the costeffectiveness estimates. The current estimated compliance costs are based largely on

the contractor studies, although some differences exist as a result of public comments

received or other information available to EPA. Such differences from the Draft RSD

and the contractor cost study will be noted where present. As a result of such

differences, EPA is presenting a range of costs in several areas. In general, the cost

estimates presented here tend to be somewhat conservative; that is, for those costs

with significant uncertainty, EPA used the higher end of the estimated range. 

Incremental compliance costs are presented for Tier 0, Tier 1 and Tier 2

locomotives on a total and per-locomotive basis. This incremental approach is

appropriate because EPA believes that the technology will be applied sequentially, as

the standards become more stringent. Locomotive cost components consist of initial

equipment costs, and operating costs. The equipment costs consist of fixed costs and

variable costs for the necessary hardware, which, when adjusted to include the

manufacturer's markup for overhead and profit, comprise the initial cost increase to

the operator. Fixed costs include engineering costs for compliance technology

development; testing costs for development, certification, production line testing (PLT)

and in-use testing; tooling costs to enable production of the hardware for compliance;

and technical support costs for training and technical support publications to be used

by personnel operating and maintaining the locomotives. Operating costs include

incremental fuel costs, (incremental to those that would be incurred without the

compliance technology) and incremental maintenance costs, including remanufacturing

costs.

A breakdown of the testing costs used in calculating fixed costs is presented in

Table 7-1, while the total fixed costs, including testing costs, are shown in the perlocomotive costs calculated in Tables 7-2A (base case) and 7-2B (high range). This

latter table is included as a sensitivity analysis to show the effects of modifying base

case assumptions regarding development costs, testing costs and operating costs (which
 Discounted costs represent the net present value of costs. 89

106

are detailed below). Tables 7-2A and 7-2B also include the estimated locomotive

populations used in allocating the fixed costs. The model categories listed in these

tables, (e.g., "Tier 0 - A" or "Tier 2 - B") represent different locomotive model types,

consistent with the descriptions of Chapters 3 and 4. Where applicable, costs are

presented in actual and discounted format. 89

7.1 Initial Cost Increase for Locomotives

The initial cost increase for locomotives (sometimes known as the first price

increase (FPI)) consists of the fixed costs to the manufacturer for such things as

investment capital, research and development, etc. and the variable costs, which are

the costs for the necessary emission control hardware on each individual locomotive.

Variable costs vary with production, while fixed costs are allocated to whatever

production level is realized.

7.1.1 Fixed Costs

Fixed costs are those that represent the initial investments that must be made by

the manufacturer before the beginning of production. These will vary in magnitude

with the emission standard (Tier 0, Tier 1, Tier 2) for which compliance is required,

and with the amount of emission control required by individual manufacturers for their

product lines, but will tend to fall into the same general categories (e.g., engineering

costs or technical support costs). It is important to note that the fixed costs necessary

to develop Tier 0 certification kits apply independently to each remanufacturer

developing a kit. Thus, if three different remanufacturers independently develop a kit

for the same model of locomotive, then the fixed cost component for that locomotive

model would be three times what it be if only one remanufacturer developed a kit. The

numbers of suppliers assumed for each model category of Tier 0 locomotive in this

analysis are shown in Tables 7-2A and 7-2B. These numbers are EPA's projection that

are based on the current numbers of independent part suppliers and remanufacturers

for the various locomotive models. EPA assumed that many current suppliers and

remanufacturers will seek to avoid the need to certify by making business

arrangements with other businesses that are certifying. Thus, the number of suppliers

assumed for each kit is less than the total number of suppliers.

Because the fixed costs are for goods and services that are useful for more than

one year of production, it is appropriate to amortize or allocate these costs over more

than one year of production. In its rulemakings, EPA normally assumes that the

manufacturers would recover their development costs within the first five years of

production. For Tier 2, this becomes important because the standards are effective for

a considerable length of time. The Tier 2 development costs were therefore assumed

to be recovered by 2010, and a separate reduced fixed cost component was used in the
107

lifetime benefit calculation after that year. After 2010 fixed costs were limited to

testing costs for PLT and in-use testing. For Tier 1, the effective period for allocation

of development work is shorter, more on the order of three years. The period of

compliance for Tier 0 is longer, due to the long useful life and staggered remanufacture

schedule of most Tier 0 locomotives, so a period of five years can be used. It is not

necessary to calculate separate compliance costs reflecting fully-recovered fixed costs

for Tiers 0 and 1 since the initial hardware costs occur only at original manufacture

(for Tier 1) or the first remanufacture (for Tier 0), and thus are applicable only during

the first few years of the program. This does not materially affect the cost-effectiveness

of the standards, and any minor error involved would be on the side of conservatism

in cost determination. Fixed costs are normally also allocated on a per-locomotive

basis according to the number of units produced. Such costs include developmental

engineering and testing costs (the latter including facility, equipment and operating

costs), as well as tooling and technical support costs as described above.

TABLE 7-1 

TESTING COSTS

Number Unit Cost Total Cost Annual Cost

Capital

Costsa

Test Systems 6 $340,000 $2,040,000

Auxiliary Equipment 4 $185,000 $740,000

Equipment Subtotal $2,780,000 $395,809

Facility Costs 4 $2,000,000 $8,000,000 $1,139,020

TOTAL CAPITAL $10,780,000 $1,534,829

Operating

Costs

Technicians 12 $70,000 $840,000

Engineers 4 $100,000 $400,000

Maintenance 6 $30,000 $180,000

Subtotal $1,420,000

Overhead $213,000

TOTAL OPERATING $1,633,000

TOTAL COSTS $3,167,829

2000-2010 After 2010a

Number of Tests/Year 200 50

Allocated Cost/Test $15,839 $32,660

Consumables $5,000 $5,000

Lost Service $300 $1,200 b

Cost/Test $21,139 $38,860

 Capital costs assumed to be recovered by 2010. a 

 Average cost for lost service time varies because of different mix of development, certification, b

production line and in-use testing.
108
109
110

Testing Costs

Testing costs include developmental testing, as well as certification testing,

production line testing and in-use testing. Developmental testing, which represents

the largest segment of the projected testing costs, is necessary for developing and

evaluating the necessary compliance strategies. The amount of developmental testing

that is necessary is determined by each individual manufacturer or remanufacturer.

Certification and PLT provide evidence of the manufacturer's initial compliance with

the applicable emission standards, and in-use testing provides evidence of the

continued durability of emission control systems. The amount of certification, PLT and

in-use testing are specified by EPA.

Testing costs include the costs of any necessary additional facilities and equipment

for emissions testing, plus engineering, operating and maintenance costs for the testing

facility. A detailed breakdown of these costs may be found in the EF&EE contractor

study, and they are summarized in Table 7-1. The contractor assumed that the major

manufacturers and a limited number of aftermarket remanufacturers would need test

equipment sufficient to equip six test cells, at a cost of $340,000 per cell, plus auxiliary

facility equipment, such as calibration gas handling equipment, particulate weighing

equipment, and a spur track for bringing locomotives to the test site, at an estimated

cost of $185,000 per facility. EF&EE assumed one such auxiliary system could service

two test cells, and that four such systems would be required, since the two major

manufacturers would already have one test site and would develop one more each. The

contractor allocated these costs over a ten year period.

The contractor assumed that although the two major manufacturers have existing

test cells, each would require an additional test cell for Tier 0 testing at an estimated

cost of $2 million per cell, but included these costs in the Tier 0 costs. EPA believes

that these facilities will be used for Tier 1 and Tier 2 testing as well as for Tier 0.

Therefore, the Agency has included the costs for two additional test cells for the major

manufacturers and two for the independent remanufacturers in the calculation of the

testing costs applicable for all tiers. EPA also received a number of comments

regarding the lack of estimated test facility costs in the Draft RSD. The comments

contained estimates ranging from $1 to 3 million. EPA believes that the cost study

estimate of $2 million each for additional test facilities is reasonable and represents

the mid-point of the range. Allocated facility costs are thus included along with

allocated equipment costs in the cost per test calculation.

In addition to allocated equipment and facility costs, testing costs also include an

operating cost component. In the cost study, EF&EE assumed that two technicians

and a supervisory engineer would be required for each test cell (or group of two test

cells in the case of the major manufacturers). The contractor also assumed costs for

test system calibration and maintenance and for overhead at a rate of 15 percent of

direct costs. EPA is assuming $5,000 per test for consumables (test fuel, reference
111

gases, electrical power, etc.), which is intended to be conservative. Since a fraction of

the tests will be for in-use testing, EPA also assumed a cost for removing the

locomotive from service for testing. Although the Agency received comments placing

this cost at up to 17 days lost time at a cost of $14,000, EPA will use the AAR estimate

of 8 days lost time at a cost of $6,000, due to the considerable AAR member experience

with FRA 92-day safety inspections. EPA estimates that in-use testing will represent

about five percent of the total test load during the early years of the program when a

great deal of development testing will be conducted, but will increase to approximately

20 percent of the total test load after 2010, when the developmental testing should be

completed and the total testing load diminishes. These figures are also reflected in

Table 7-1.

As can be seen from Table 7-1, these costs when allocated over the estimated

testing requirement, amount to about $21,000 per test prior to 2010 and about $39,000

per test after 2010 when the developmental testing is completed. This differs from

both EPA's original estimate of $10,000 per test and the estimate of $10,237 per test

provided in the EF&EE cost study. However, as noted above, EPA has added allocated

facility costs and allowances for consumables and lost locomotive service to the

estimated costs, and has adjusted the cost-per-test calculation accordingly. 

EPA also received a number of testing cost estimates in the public comments; the

near-term estimates for the type of testing that will most likely be required tended to

fall into the $20,000 to $30,000 range. The above-mentioned adjusted cost per test falls

into the lower end of that range, so as a sensitivity analysis EPA assumed a high range

cost per test of 1.5 times both of the costs listed in Table 7-1; the resulting testing costs

will be used in calculating the high range cost and cost/benefit figures that are

presented in Table 7-2B.

Engineering Costs

The engineering costs category represents the estimated average cost for the

number of engineering work years projected to be required to develop the calibrations

and hardware necessary for meeting the emission standards. This also includes the

effort for any ancillary changes that must be made to the locomotives to accommodate

the required new hardware. The engineering costs used in the current analysis were

taken from the EF&EE cost study and are shown in Tables 7-2A (base case) and 7-2B

(high range). In Table 7-2B the engineering costs were increased by a factor of 1.5 as

a part of the sensitivity analysis.

Tooling Costs

Tooling costs are also shown in the fixed costs portion of Tables 7-2 A and 7-2B.

These include costs for any additional or modified tooling necessary to produce the

emission control hardware, as well as for any required setup changes. Because Tier
112

0 compliance is estimated to be achieved through calibration changes or through

hardware obtained from suppliers (particularly in the case of aftermarket

remanufacturers), no specific tooling costs were estimated for Tier 0. Tooling costs for

Tier 0 parts were assumed to be included in the component costs to the

remanufacturer. Tooling costs for the other tiers were taken from the cost study.

Technical Support

Technical support consists of any changes that would be required in the technical

support that manufacturers provide to users. This would include any necessary

operator or maintenance training and changes to technical publications that provide

operating and maintenance guidance. These costs were not included in the Draft RSD,

but were estimated in the EF&EE cost study, and are included in the current analysis.

These costs are also included in the fixed costs portion of Tables 7-2A and 7-2B.

7.1.2. Variable Costs

Hardware

Hardware requirements for meeting the applicable emission standards will vary

with the stringency of the standards, i.e., Tier 0, Tier 1, or Tier 2, and by

manufacturer, according to the hardware changes required to meet the standards.

These variations are outlined below and are discussed more fully in the Acurex

technology study and the EF&EE cost study. In general, however, manufacturers will

need to use some combination of fuel injection timing calibration; fuel injector,

turbocharger, and/or charge air cooling improvements; and possibly combustion

chamber or piston modifications. Particularly for Tier 0, different combinations of

these strategies will be used for different locomotives. A listing of these strategies,

along with their projected costs and estimated usage, is presented in Table 7-3. For

example, it is projected that about 50 percent of Tier 0 locomotives will have timing

retarded by 2 degrees, and the other 50 percent will have timing retarded by 4 degrees.

Similarly, it is projected that 60 percent of Tier 0 locomotives will add 4-pass

aftercoolers. Representative model combinations are shown in Tables 7-2A and 7-2B.

No separate model cases are shown for passenger locomotives, since these are generally

variations of similar line-haul locomotives and should thus incur similar costs (fixed

as well as variable). However passenger locomotives are included in the total cost

calculations since the costs should be similar to those for freight locomotives.
 "Cost Estimations for Emission Control Related Component/ System and Cost 90

Methodology Description", LeRoy H. Lindgren, March, 1978 (EPA-460/3-78-002).

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Assembly Costs

Assembly costs include the labor and overhead costs for retrofitting (in the case

of Tier 0) or for initial installation of the new or improved hardware. These will also

vary with the characteristics of individual locomotives and the type of hardware

necessary for compliance with the applicable emission standards. These costs are

included in the summary figures in Tables 7-2A and 7-2B, and are discussed more fully

in the contractor cost study.

Table 7-3

Incremental Hardware Cost And Usage

Expected Cost per Percent of Locomotives Using

Technology Locomotive Technology

Tier 0 Tier 1 Tier 2

 2 deg timing retard -- 50% 100%

 4 deg timing retard -- 50% 100%

 4 pass aftercooler $5,000 60%

Improved mechanical $800 30%

injectors

Add electronic fuel injection $35,000 13%

Improved electronic injectors $2,000 37% 100% 100%

Engine Modifications $800 20% 50%

Improved turbocharger $25,000 30% 25%

Split cooling $25,000 75% 100%

High pressure injection $2,000 100% 100%

Combustion chamber design $800 100% 100%

7.1.3. Total Locomotive Cost Increase

The fixed and variable costs, together with a manufacturer markup for overhead

and profit, comprise the total manufacturing costs which represent the initial cost

increase, or FPI, to the operator. A conservative manufacturer markup of 20 percent

was assumed, based on the amount normally used as a target figure in the automotive

industry. Although the actual markup for automobiles and trucks tends to vary with 90

economic conditions and other factors, this target figure was used for locomotives for

the sake of conservatism and in the absence of any data on the actual markups
114

achieved in the locomotive industry. Given the competitive nature of the industry,

EPA believes the actual markups are likely to be lower. The total manufacturing costs

or FPI are shown in Tables 7-2A and 7-2B. 

Tier 0 Locomotives

In calculating the estimated FPI for Tier 0 locomotives, EPA assumed that the

locomotives could be grouped into 5 categories (or engine families): older and newer

line-haul locomotives from the two major manufacturers, and switch locomotives from

one manufacturer. This latter group was not included in the EF&EE cost study

because the contractor did not feel it would be cost-effective to upgrade these

locomotives. However, EPA believes a significant number will be certified, due to the

relatively low cost involved. The EF&EE cost study estimated that it may be more

cost-effective to improve the existing unit injectors of older locomotives, since they

typically do not accumulate as many miles each year as the newer locomotives.

However, based on comments received, EPA does not necessarily concur that this will

be true for all such locomotives, and has included electronic injection systems for some

of the older locomotives as well. The other major difference in costs results from the

need for an improved turbocharger for locomotives with higher smoke emissions, which

would not be required for locomotives which did not have this problem. Changes in

injection timing calibrations would likely be used for all these scenarios.

Tier 1 Locomotives

The estimated initial cost increase for Tier 1 locomotives are shown in Tables 7-2A

and 7-2B. The EF&EE cost study made the distinction between mechanical and

electronic injection designs for Tier 1 locomotives. Fuel injection cost differences would

thus arise from the fact that some current locomotives are already equipped with

electronic injector systems, which would merely need to be upgraded, rather than

replaced. EPA believes that all Tier 1 locomotives will have injection systems that are

upgraded versions of the current electronic injectors. Therefore, the costs used in all

calculations are based on the upgraded electronic injector scenario, rather than

conversion from mechanical to electronic injection. Improved charge air cooling and

limited in-cylinder modifications, e.g., for reduced oil consumption or higher

compression ratio, as well as changes in injection timing calibrations, were also

estimated to be required. EPA also believes that early versions of the new engine

designs that will be used to meet the Tier 2 standards will make their appearance

during the Tier 1 period. Thus, the tables show two Tier 1 models for each

manufacturer.
115

Tier 2 Locomotives

The estimated initial cost increases for Tier 2 locomotives are shown in Tables 7-

2A and 7-2B. Costs for Tier 2 compliance are based on new and improved engine

designs already under development by the two major manufacturers. The existence

of these designs, plus the 7 years of lead time available for development should result

in cleaner engines that are able to meet the Tier 2 standards with minimum

incremental costs over the developmental costs that would otherwise have been

incurred for development of the uncontrolled engines. Again, the basic strategies likely

to be used are injection timing calibrations, low-temperature charge air coolers and

fuel injection improvements, largely the addition of rate shaping capability in the

latter case. The Acurex report projected a possible need for EGR for some Tier 2

locomotives, however, EF&EE and EPA did not include EGR in the projected

compliance strategies. EPA believes that if EGR were to be used at all, it would only

be used on the lower power notches. It is also important to note that since the

manufacturers are expected to introduce early versions of these new models during the

Tier 1 time period, some of the emission control development cost is assigned to the

Tier 1 locomotives. Compliance with the Tier 2 standards will actually be a

continuation of the Tier 1 development process.

7.2. Incremental Operating Cost Increases

The incremental operating costs include any increase or decrease in the amount

of fuel consumed as a result of the new standards, plus any incremental maintenance

costs. This latter category would include maintenance on any new hardware required

or additional maintenance on existing hardware. Any incremental subsequent

remanufacture costs would also be included in the total. These costs are shown in the

operating cost sections of Tables 7-2A and 7-2B.

7.2.1. Incremental Fuel Cost

EPA estimated the fuel economy ramifications of various emission control

technologies in the Draft RSD. Public comments on the subject were also received, and

incremental fuel costs (or savings) were also presented for the strategies considered in

the contractor cost study. These are expressed in terms of percent increases or

decreases from current levels. However, estimates for current fuel consumption levels

show considerable variation.

In the Draft RSD, EPA calculated an annual per-locomotive cost of a one

percent decrease/increase in fuel economy by multiplying the cost of fuel used by

Class I railroads in 1992, $1,913,000,000, by a one percent fuel economy

penalty/benefit and divided by the number of locomotives in use during 1992,

rounded to the nearest thousand (i.e. approximately 18,000 locomotives). In terms

of gallons of fuel consumed (at $0.63 per gallon), this represents roughly 167,900
116

gallons. Total fuel economy penalties/benefits of one percent from pre-regulated

baseline levels would thus result in a calculated annual per-locomotive cost or

benefit of $1,062.

On the other hand, in the contractor cost study, EF&EE assumed total per

locomotive fuel consumption rates of 104,000 and 297,000 gallons per year, depending

on application (i.e., light or heavy usage). EF&EE assumed a fuel consumption rate

of 445,000 gallons per year for the advanced technology engines projected to be used

for Tier 2 compliance. However, in their comments on the NPRM, EMD projected a

fuel consumption rate of 350,000 gallons per year for their new 6,000hp locomotives.

Since the OEM has developmental data for their products and should thus be in a

better position to make fuel consumption estimates for their new technology, EPA will

use this estimate for Tier 2, along with the Tier 0 and Tier 1 estimates from the cost

study. The fuel consumption rates assumed are shown in the operating costs section

of Tables 7-2A and 7-2B. These fuel rates, however, are only used for these per

locomotive calculations; total costs were calculated from total fuel consumption

estimates provided by the railroads.

As stated above, EPA received comments concerning projected fuel economy

penalties. Some of these comments projected penalties as high as 5-10 percent,

however this latter estimate appears to assume use of EGR on all models for meeting

the Tier 2 standards. As stated above, EPA does not believe this will be required, and

has projected fuel economy penalties of two percent as its best estimate of the Tier 2

fuel economy effects of the current rulemaking. Based on past developments in the

industry, EPA further believes that manufacturers will make every effort to eliminate

any initial fuel consumption penalties, and will have largely succeeded by 2010.

However, projecting the necessary developmental costs involved and resulting fuel

consumption levels is difficult at this time. Thus, for the sake of conservatism, the two

percent projected fuel economy penalty will be retained in the analysis for the full 41

years covered by the analysis.

EPA also projected fuel economy penalties of 1-2 percent for Tier 0 locomotives,

depending on other modifications that could serve to mitigate any fuel economy

decrease involved. However, some Tier 0 locomotive models converting from

mechanical to electronic fuel injection may actually see a decrease in fuel consumption.

For Tier 1, EPA has assumed a one percent penalty, since the additional lead time

afforded for meeting Tier 1 standards should allow additional development for the

manufacturers to address any more negative fuel consumption effects. Nevertheless,

as a sensitivity analysis, the Agency has also included a scenario which doubles the

base-case incremental fuel consumption estimates. These are in the high range cost

estimates presented in Table 7-2B and the high-range cost-effectiveness analysis

shown in Table 7-5. 
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7.2.2. Incremental Maintenance

Routine Maintenance

EPA did not estimate any incremental maintenance costs in the Draft RSD.

However, comments submitted by EMD stated that additional cost would be incurred

for periodic replacement of electronic fuel injectors (which are routinely replaced at

periodic intervals between remanufactures), and electronic injection wiring harnesses

(which would also require replacement outside the normal remanufacture cycle due to

embrittlement of the insulation from the heat generated by the engine). EF&EE

agreed in its cost study that these would be legitimate costs, and provided estimated

incremental costs for their replacement. EPA is including the cost of these

replacements in the estimated maintenance costs for Tier 0 and Tier 1 locomotives, and

the cost of improved injector replacement for Tier 2 locomotives. In addition, the

contractor projected a small additional cost for routine periodic replacement of

improved unit injectors, based on the difference in cost between the standard and

improved versions. EPA has included the incremental costs for Tier 0 mechanical

injector replacement in the maintenance costs. All of these periodic costs are converted

to an average annual component and are included in the incremental maintenance

costs shown in the operating costs section of Tables 7-2A and 7-2B. For purposes of

this analysis, Tier 0 locomotives were assumed to have an average remaining service

life at the time of remanufacture of 15 and 21 years, respectively, for older and newer

locomotives, as shown in Tables 7-2A and 7-2B. 

Subsequent Remanufactures

 In addition to the initial equipment costs at time of original manufacture, and

incremental maintenance costs for components that were upgraded at the time of

manufacture/initial remanufacture, there will be some increase in costs at the time of

each subsequent remanufacture of the locomotives. These costs are the incremental

price increases in equipment that is routinely replaced at time of remanufacture.

These costs are increased due to the improved parts necessary to meet the applicable

emission standards. These costs are also included in the incremental maintenance

costs presented in Table 7-3, and are discussed in greater detail in the EF&EE cost

study. 

7.2.3. Total Cost Increase

The estimated increased fuel costs and maintenance costs are included in the

incremental operating costs for Tier 0, Tier 1 and Tier 2 locomotives shown in Tables

7-2A and 7-2B. These operating costs are presented as annual incremental costs and

lifetime incremental costs for the estimated service life of the locomotive, in both actual

and net present value (NPV) form. These operating costs are added to the first price

increase to yield the lifetime costs per locomotive presented in the table. As discussed
118

above, EPA has based its analysis on public comments received and on engineering

judgement, as well as on the contractor study. Again, since there was considerable

variation in the estimated fuel consumption figures contained in the comments and

other sources, the incremental fuel consumption estimates from the base-case analysis

were doubled to form a high-range estimate, which is used as a sensitivity analysis.

7.3. Total Program Costs and Cost-effectiveness

 Tables 7-4 and 7-5 summarize the lifetime costs and emission benefits of the final

locomotive rulemaking. While the costs presented are applicable for both NOx and PM

reductions, the calculated benefits shown are for NOx only. However, it should be

remembered that there are also significant emission reductions in PM (275,000 metric

tons) and HC (400,000 metric tons). The costs are presented in an undiscounted

(actual), and discounted (7% NPV) format. Costs and benefits were computed over a

forty-one year program run to ensure complete fleet turnover, due to the extremely

long service life of the typical locomotive. For the sake of consistency, total fuel

consumption was calculated using the classwide fuel consumption rates used for

calculation of the benefits in Chapter 6. Additional tables showing the year-by-year

costs and emission benefits in both undiscounted and discounted form for the entire 41-

year program can be found in Appendix F. Table F-1 shows undiscounted benefits and

Table F-2 shows the benefits discounted at a rate of 7 percent. 

The Draft RSD estimated the NOx cost-effectiveness for the program as a whole

at $175 per metric ton. Based on the costs presented above and recomputed benefits,

EPA has recalculated the cost-effectiveness for the total program at $163 per metric

ton of NOx reduction for the base case (shown in Table 7-4) and $253 per metric ton for

the high range case (shown in Table 7-5). As stated earlier, the high range case

includes developmental engineering and testing costs at 150 percent of the base case

and fuel consumption costs that are double the base case. Both of these sets of figures

compare quite favorably to other NOx control strategies that have been adopted in

recent years. For example, the cost-effectiveness for the large nonroad engines

rulemaking was $160 to $360 per ton of NOx. The rule becomes even more costeffective when the above-mentioned HC and PM benefits are considered.

EPA also calculated the marginal cost-effectiveness of the three tiers. The results

of this calculation are shown in Appendix F, and are summarized in Table 7-6. To

determine the marginal costs and benefits, EPA considered two additional scenarios:

one in which the Tier 2 standards were eliminated so that the Tier 1 standards

continued to apply after 2005; and one in which both the Tier 1 and Tier 2 standards

were eliminated so that the Tier 0 standards continued to apply for the duration of the

program. The total costs, NOx benefits and cost-effectiveness for these two scenarios

are shown in the appendix. From these scenarios, EPA calculated the marginal costeffectiveness for each of the three tiers of standards by dividing the marginal costs by

the marginal benefits, as shown Table 7-6. The Tier 0 figures show the cost, benefits,
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and cost-effectiveness of continuing the Tier 0 standards for the full period 2000-2040.

The Tier 1 figures show the marginal costs, benefits and cost-effectiveness associated

with the Tier 1 standards, assuming that they were continued after 2005. The Tier 2

figures show the marginal costs, benefits and cost-effectiveness of the Tier 2 standards,

which is calculated from the difference in costs and benefits between the total costs

and benefits for all three tiers of standards (as shown in Table 7-4) and the previous

scenario where the Tier 1 costs and benefits were continued from 2005-2040. As can

be seen from the table, the costs for Tier 1 and Tier 2 are significantly higher than

those for Tier 0. The differential would likely have been even greater if the costs were

estimated over a shorter period of time. For example, when the cost-effectiveness is

calculated for a 20 year period, rather than 41 years, the cost per ton for the total

program increases by more than 40 percent, which could mean costs of upwards of $600

per ton at the high end of the cost range.
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Table 7-4

Cost-Effectiveness Analysis: Base Case

Category Total Costs

TIER 0

 Average number of Tier 0 locomotives produced per year (2000-2013) 1,214

 Average number of Tier 0 locomotives in the fleet (2000-2040) 10,803

INCREMENTAL COSTS:

 Initial Manufacture $470,446,480

 Fuel consumption $435,742,226

 Maintenance $217,159,792

TOTAL $1,123,348,498

NPV $584,926,672

TIER 1

 Average number of Tier1 locomotives produced per year (2002-2004) 480

 Average number of Tier 1 locomotives in the fleet (2002-2040) 1,324

INCREMENTAL COSTS:

 Initial Manufacture $102,890,062

 Fuel consumption $79,754,324

 Maintenance $32,013,080

TOTAL $214,657,466

NPV $132,572,277

TIER 2

 Average number of Tier 2 locomotives produced per year (2005-2040) 462

 Average number of Tier 2 locomotives in the fleet (2005-2040) 9,078

INCREMENTAL COSTS:

 Initial Manufacture $669,994,839

 Fuel consumption $1,186,615,407

 Maintenance $78,433,920

TOTAL $1,935,044,166

NPV $613,541,238

TOTAL COSTS $3,273,050,130

NPV $1,331,040,187

TOTAL NOx BENEFIT (Tons-M) 20,052,552

COST EFFECTIVENESS ($/Ton) $163

NPV $66
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Table 7-5

Cost-Effectiveness Analysis: High Range

Category Total Costs

TIER 0

 Average number of Tier 0 locomotives produced per year (2000-2013) 1,214

 Average number of Tier 0 locomotives in the fleet (2000-2040) 10,803

INCREMENTAL COSTS:

 Initial Manufacture $502,544,778

 Fuel consumption $871,484,452

 Maintenance $217,159,792

TOTAL $1,591,189,022

NPV $782,324,482

TIER 1

 Average number of Tier1 locomotives produced per year (2002-2004) 480

 Average number of Tier 1 locomotives in the fleet (2002-2040) 1,324

INCREMENTAL COSTS:

 Initial Manufacture $134,317,119

 Fuel consumption $159,508,649

 Maintenance $32,013,080

TOTAL $325,838,848

NPV $167,500,335

TIER 2

 Average number of Tier 2 locomotives produced per year (2005-2040) 462

 Average number of Tier 2 locomotives in the fleet (2005-2040) 9,078

INCREMENTAL COSTS:

 Initial Manufacture $706,878,325

 Fuel consumption $2,373,230,814

 Maintenance $78,433,920

TOTAL $3,158,543,059

NPV $951,097,583

TOTAL COSTS $5,075,570,929

NPV $1,900,922,399

TOTAL NOx BENEFIT (Tons-M) 20,052,552

COST EFFECTIVENESS ($/Ton) $253

NPV $95
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Table 7-6

Marginal Cost-Effectiveness of Each Tier of Standards

Locomotive Standards Base Case High Range

TIER 0 

 Total Costs $2,422,421,411 $3,572,022,108

 Total NOx Benefits 12,809,089 12,809,089

Cost-effectiveness ($/Ton) $189 $279

TIER 1

 Marginal Costs $850,628,719 $1,503,548,820

 Marginal NOx Benefits 4,172,037 4,172,037

Cost-effectiveness ($/Ton) $204 $360

TIER 2

 Marginal Costs $618,662,877 $1,229,466,813

 Marginal NOx Benefits 3,071,426 3,071,426

Cost-effectiveness ($/Ton) $201 $400
123

APPENDICES

(Note: the appendices are contained in a separate document.)