United States

Environmental Protection

Agency

Air and Radiation EPA420-P-02-014

December 2002

NR-005b

Median Life, Annual

Activity, and Load Factor

Values for Nonroad Engine

Emissions Modeling

 Printed on Recycled Paper
EPA420-P-02-014

December 2002

Median Life, Annual Activity, and Load Factor

Values for Nonroad Engine Emissions Modeling

NR-005b

Assessment and Standards Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

NOTICE

This technical report does not necessarily represent final EPA decisions or positions.

It is intended to present technical analysis of issues using data that are currently available.

The purpose in the release of such reports is to facilitate the exchange of

technical information and to inform the public of technical developments which

may form the basis for a final EPA decision, position, or regulatory action.
1

where Pop = Engine Population

Power = Average Power (hp)

LF = Load Factor (fraction of available power)

A = Activity (hrs/yr)

EF = Emission Factor (g/hp-hr) 

Median Life, Annual Activity, and Load Factor Values

 for Nonroad Engine Emissions Modeling

Report No. NR-005b

Revised December 6, 2002

Assessment and Standards Division

EPA, Office of Transportation and Air Quality

Purpose

EPA’s NONROAD model computes emission inventories for nonroad engines. This

report documents the default input values of median life, annual activity, and load factor for

various types of nonroad engines. The model uses annual activity and load factor values to

calculate yearly emissions for each engine type. In addition, the model uses activity and load

factor, in combination with median life, to calculate the fleet age distributions for each engine

type, as it projects future (or past) engine populations. 

Introduction

This report documents the default annual activity, load factor, and median life values. 

The model uses the following equation to calculate exhaust emissions from nonroad engines. 

The derivation of default values for equipment population, average rated power, and emission

factors are discussed in reports NR-006b, NR-009b, and NR-010c. 

This report also documents the default values for the median life of engines. In the

population input files (*.pop) this parameter is expressed in “hours of life at full load.” In

developing the age distribution for a given equipment type, the model begins by converting the

hours-at-full-load to years at average load, on the basis of average activity and load factor, as

defined above and as shown in the equation below. 
2

The use of median life in calculating the scrappage and resulting age distribution of each

equipment type is explained in report NR-007a, “Calculation of Age Distributions in the

Nonroad Model: Growth and Scrappage.”

Values Used in NONROAD for Median Life, Annual Activity, and Load Factor

This report describes the default estimates for median life, activity, and load factor used

as default data in the input files provided withNONROAD. 

Median Life

Engine life varies with engine type and power level. In general, larger engines last longer

than smaller ones, and diesel engines last longer than gasoline engines. 

The NONROAD model uses median (expected) life estimates based primarily on those used in

the OFFROAD model, developed by the California Air Resources Board (ARB)(3). These

estimates are listed by horsepower class and engine type in Table 1, with horsepower classes

defined in Table 2. In certain cases the ARB horsepower ranges were adjusted to match the

ranges used in the NONROAD model. The 120 hp dividing point used by ARB was the 100 hp

point in NONROAD; the 250 hp point was used as the 300 hp point in NONROAD; and ARB’s 

500 hp point was used as the 600 hp dividing point in NONROAD. Additional modifications

that EPA made to the ARB median life values for diesel engines, small gasoline engines, and

recreational equipment are described below.

Table 1. Expected Engine Life in Hours at Full Load (3, 4)

Engine

Type

HP 1 HP 2 HP 3 HP 4 HP 5 HP 6 HP 7 HP 8 HP 9 HP 10

Diesel 2500 2500 2500 4667 4667 4667 7000 7000 7000 --

2-stroke

Gasoline

150 200 750 -- -- -- -- -- -- --
3

4-stroke

Gasoline

200 400 750 1500 3000 3000 3000 3000 3000 3000

CNG/

LPG

200 400 750 1500 3000 3000 3000 3000 3000 3000

Table 2. Horsepower Classes for Median Life (3, 4)

HP Class Diesel 2-stroke 4-stroke

HP 1 16 3 6

HP 2 17-25 3-16 6-16

HP 3 26-50 16-25 16-25

HP 4 51-100 26-50 26-50

HP 5 101-175 51-100 51-100

HP 6 176-300 101-175 101-175

HP 7 301-600 176-250 176-300

HP 8 601-750 301-600 301-600

HP 9 751+ 601-750 601-750

HP 10 -- 751+ 751+

In prior draft versions of NONROAD the median life estimates of most equipment (CI

and SI ) were based on the values in the 1997 documentation for the ARB OFFROAD model,

prepared by Energy and Environmental Analysis (EEA)(3). These are presented in EPA's

technical report NR-005a (revised 6/15/1998) and in Table 3 below. For CI these numbers were

either 1,250, 2,500, 4,000, or 6,000 hours at full load, depending on rated horsepower.
4

Table 3. CI Median Life Comparison

Hp Range Previous NONROAD

Median Life

New NONROAD

Median Life

Regulatory

Useful Life*

0 - 16 1,250 2,500 3,000

16 - 25 2,500 2,500 3,000

25 - 50 2,500 2,500 5,000

50 - 300 4,000 4,667 8,000

300+ 6,000 7,000 8,000

* The Regulatory Useful Life is considered to represent in-use loads, rather than full load. 

NONROAD model diesel load factors range from 0.21 to 0.59.

In researching the issues related to estimation of equipment sales, population, diesel fuel

consumption, load factors, and median life, EPA asked EEA for more complete documentation

of the values that had been provided to ARB. At EPA's request, EEA supplemented the

documentation of their previous work. The resulting report is attached as Appendix B (4).

After reviewing the new EEA report, EPA determined that modifications to the median

life estimates were appropriate. Information that EEA gathered from highway diesel engine

manufacturers suggested an expected life for heavy-duty diesel highway engines of 7,000 hours

at full load. In preparing initial estimates for use in OFFROAD, EEA had reduced this estimate

by 15% to compensate for the "rough-duty" use of off-road engines relative to highway engines.

This yielded the 6,000 hour estimate mentioned above for engines over 300 hp. In reviewing this

work, EPA determined that it did not make sense to reduce the 7000 hour estimate for off-road

applications, since when engines are used in off-road applications they are typically derated to

compensate for the rougher operating conditions. Thus the horsepower rating of the offroad

engine may be lower than its highway counterpart, but its expected life would not be lower.

EEA estimated medium duty diesel engine life to be two-thirds that of the heavy-duty

engines and applied that to diesel engines in the range of 50 - 300 hp. 

EPA applied this same factor to the 7000 hour value yielding a median life estimate of 4667

hours at full load for 50 - 300 hp engines. For engines in the 16 - 50 hp range EEA based its

estimate of 2500 hours at full load on information from light-duty highway diesels. No

adjustments were made by EEA or EPA for off-road use, since these engines are typically not

used in rough duty applications. For engines under 16 hp EEA had somewhat arbitrarily cut the

life estimate of the 16 - 50 hp engines in half, yielding the 1250 hour estimate mentioned above. 

Since this low estimate was not supported by any data, and since after accounting for load factors

it can yield expected life values less than the regulatory useful life set by EPA for these engines,
5

EPA decided to use the 2500 hour estimate in NONROAD for all diesel engines from 0 - 50 hp,

rather than have a separate lower life category under 16 hp. 

Liquid petroleum gas (LPG) and compressed natural gas (CNG) engines are primarily

four-stroke spark-ignition engines and hence have many similarities with four-stroke gasoline

engines. Because LPG and CNG engines are similar in design to gasoline engines, their median

life is likely to be similar to the median life of gasoline engines. For this reason and the lack of

relevant data to the contrary, LPG and CNG engines are assumed to have the same median life as

gasoline engines in the NONROAD model.

The values described represent the most comprehensive review available of the engine

life associated with engine type and power level. They represent median values of engine life,

not distinguishing the engine by make or model. Individual engine models may have longer or

shorter median lives. Surveys of engine life by application or engine type are encouraged to

improve the estimates shown here. 

Small Spark-Ignition Engines (rated at <25 hp)

The median life (the point where 50% of engines have been scrapped) for several

applications of nonroad engines have been estimated previously in terms of years of use(5,8). 

For use in the NONROAD model, these estimates were converted from units of years to units of

hours using the equation previously shown. Median life in years from Table 4 was multiplied by

hours per year and load factor (described later in the report and given in Table 5) to create the

Median Life (Hours at Full Load) entry in Table 4, which is used as input to the NONROAD

model.

The final values for the median life used in NONROAD for these selected applications

are shown in Table 4. Lower or higher power level engines use the default values from ARB per

Tables 1 and 2 above. 

Table 4. Median Life for the Bulk of Several Small Spark-Ignition Engine Applications

Application Use Power

(min.)

Power

(max.)

Median Life 

(Hours at Full Load)

Median Life 

(Years) (5, 6)

Lawn Mowers Residential 1 6 47.9 5.8

Commercial 1 6 268 2

Trimmer/Edger/Cutter Residential 0 3 35.3 4.3

Commercial 0 3 286.8 2.3

Chainsaws Residential 0 6 39.2 4.3

Commercial 0 6 191 0.9
6

Leaf Blower/Vacuum Residential 0 6 40.4 4.3

Commercial 0 6 609.7 2.3

Tillers Residential 0 11 39.4 5.8

Commercial 0 11 830.7 4.4

Snowblowers Residential 0 6 12.3 4.4

Commercial 0 6 209.4 4.4

Commercial Turf Commercial 3 25 988.9 2.9

Rear Engine Rider Residential 3 16 79.3 5.8

Commercial 6 16 627 2.9

Lawn and Garden

Tractor

Residential 3 25 114.8 5.8

Commercial 6 25 920 2.9

Recreational Marine Stern-Drive/Inboard Engines (SD/I)

For purposes of median life the previous publicly available version of NONROAD

treated gasoline-powered stern-drive and inboard engines the same as spark-ignition engines over

50 hp. Per Table 1 this meant they were assigned a median life of 3,000 hours at full load. Upon

review, it became apparent that when annualized, this result was implausible; this median life,

divided by the product of activity and load factor, gave an annualized estimate of 300 years

(3,000 hours/(48 hr/year×0.21) = 300 years). To address this issue, NONROAD2002 assumes a

median life of 20 years (197 hrs at full load) for all gasoline SD/I engines. 

Recreational Equipment

The median life values used for snowmobiles, all-terrain vehicles (ATVs), and offroad

motorcycles are given in Table 5. These estimates were developed for the proposed rulemaking

for large spark-ignition and recreational engines (19). Since the final rule was just completed in

September 2002, changes that have occurred subsequent to the proposal have not been

incorporated in this version of the model. The regulatory support document for the final rule

provides a detailed description of the most recent median life estimates (21).
7

Table 5. Median Life for Snowmobiles, All-Terrain Vehicles, and Offroad Motorcycles

Application Median Life

(Hours at Full Load or Miles)

Median Life

(Years)

Snowmobiles 174 hours 9

All-Terrain Vehicles 20,410 miles 13

Offroad Motorcycles 21,600 miles 9

Equipment Activity

Activity represents annual equipment usage expressed in hours of operation (hours/year). 

Except as noted below, we use equipment activity estimates from a 1998 database developed by

Power Systems Research, Inc. (PSR), an independent research firm, as default input values in

draft NONROAD2002. The PSR data represents the most comprehensive review of applicationspecific activity available to EPA. PSR conducts several yearly surveys of equipment owners

and determines a mean usage rate for engines by application and fuel type(7). The PSR

methodology is described and evaluated in a report produced by E.H. Pechan & Associates (8). 

We are unaware of activity estimates specific to LPG and CNG engines. These engines

are similar to gasoline engines in that they employ spark-ignition. Because LPG and CNG

engines are presumably used in applications where gasoline engines are used, we assume that

their usage rates are similar to those for gasoline engines.

The activities in the draft NONROAD2002 model for each equipment type are provided

in Appendix A.

Load Factor

Rated power is the maximum power level that an engine is designed to produce at its

rated speed. Engines typically operate at a variety of speeds and loads, and operation at rated

power for extended periods is rare. To take into account the effect of operation at idle and partial

load conditions, as well as transient operation, a load factor is developed to indicate the average

proportion of rated power used. For example, at a 0.3 (or 30 percent) load factor, an engine rated

at 100 hp would be producing an average of 30 hp over the course of normal operation. Load

factor can vary widely for nonroad engines, depending on their usage patterns.

PSR also estimates the load factor from surveys of equipment users. PSR calculates the

fraction of load from the estimate of hours of usage per year, the fuel consumption per year, and

the fuel consumption rate at rated power for each engine in the field. A median fraction of

available power is determined for specific applications. The load factor is determined from
8

actual and maximum fuel consumption rates for various pieces of equipment. For reference, the

PSR methodology is explained in detail in the Pechan report(8).

For the draft NONROAD2002 model, PSR load factors were used with the exceptions

described below. As was the case for activity levels, LPG and CNG engines are assigned the

load factors for gasoline engines. The load factors in the draft NONROAD2002 model for each

equipment type are also provided in Appendix A.

Small (<25 hp) Spark-Ignition Engines

The activity for small spark-ignition engines, mainly lawn and garden equipment, were

derived from data supplied to EPA during the comment period for the regulation of these

applications. The supporting documentation for those regulations include estimates of activity for

a few important applications(5). These alternate values are shown in Table 6 and represent a

departure from the PSR values. For applications not shown in Table 6, PSR values were used 

because the PSR survey includes such categories as construction, agricultural, commercial, and

many other engines applications that were not included in the data submitted for the rulemaking. 

The load factors for lawn mowers, tillers, snowblowers, rear engine riders, and lawn and

garden tractors in Table 6 were also derived from the same data supplied to EPA during the

comment period for the regulation of small SI engines. 

Table 6. Usage and Load Factors for Several Small Spark-Ignition Engine Applications

Application Use Annual Hours Load Factor

(fraction of power)

Lawn Mowers Residential 25 0.33

Commercial 406 0.33

Trimmer/Edger/Cutter Residential 9 0.91

Commercial 137 0.91

Chainsaws Residential 13 0.70

Commercial 303 0.70

Leaf Blower\Vacuum Residential 10 0.94

Commercial 282 0.94

Tillers Residential 17 0.40

Commercial 472 0.40
9

Snowblowers Residential 8 0.35

Commercial 136 0.35

Commercial Turf Commercial 682 0.60

Rear Engine Rider Residential 36 0.38

Commercial 569 0.38

Lawn and Garden Tractor Residential 45 0.44

Commercial 721 0.44

For the three most populous handheld applications (i.e., chainsaws,

trimmers/edgers/brush cutters, and blowers/vacuums), the previous version of NONROAD

assumed a load factor of 0.50. The estimate of 0.50 was supplied by manufacturers to the

California Air Resource Board in 1990 and is based on manufacturers’ belief that it accurately

reflects the typical usage pattern of most portable two-stroke power equipment. In support of a

more recent effort to analyze the test cycle currently used for certification of Phase 1 handheld

engines, manufacturers monitored the in-use operation of a number of chainsaws, 

trimmers/edgers/brush cutters, and blowers/vacuums to determine the appropriate weighting of

wide open throttle (WOT) and idle operation for certification testing purposes. Based on this

information, the load factors for chainsaws, trimmers/edgers/brush cutters, and blowers/vacuums

are now 0.70, 0.91, and 0.94, respectively (6).

For commercial turf equipment, the previous load factor of 0.50 was revised to 0.60,

based on 1998 PSR data.

Many of the small spark-ignited engines are used in lawn and garden equipment

applications, and lawn and garden equipment is used both by commercial and residential users. 

The commercial users are grounds keepers for nonresidential, large apartment complexes, and

some single-family homes. Commercial equipment therefore has significantly different usage in

terms of hours per year and weekday and weekend day than residential equipment. To account

for these differences in equipment usage, separate SCC’s are used to distinguish commercial

from residential lawn and garden equipment.

Recreational Marine Engines

As described in the technical report on nonroad engine populations (2) , recreational

marine engines are divided into three applications; inboard, outboard, and personal watercraft. 

Due to the similarity of engines, the inboard category includes the inboard/outboard sterndrive

engines formerly considered as a separate SCC category. The inboard engines are associated

with the PSR category "powerboats." 
10

The June 1998 draft of the NONROAD model used fuel consumption data to estimate

activity for outboard engines (9). The April 1999 draft version and subsequent drafts of the

model have used activity data collected during the recreational marine rulemaking process,

provided by the National Marine Manufacturers Association and individual marine vessel

manufacturers (10). Draft NONROAD2002 continues to use these estimates, which are shown in

Table 7.

Table 7. Recreational Marine Activity and Load Factors

Recreational Marine

Engine/Equipment Type

Activity

(hours/year)

Load Factor

(fraction of

power)

Four-stroke Inboards 47.6 0.21

Two-stroke Outboards 34.8 0.21

Personal Watercraft 77.3 0.21

Based on other comments, we revised the load factor to reflect the average load for the

marine engine certification test cycle (20.7%) . In-use data for load factor arenot available., and

the PSR estimates of load factor (32% for outboard, 38% for inboard, and 42% for personal

watercraft) are not currently documented. 

Recreational Equipment

In the course of the rulemaking process for recreational equipment and large sparkignition engines, the activity and load factor estimates for recreational equipment (i.e.,

snowmobiles, all-terrain vehicles, and off-road motorcycles) have been updated in Draft

NONROAD2002 (11,12). In estimating operating hoursfor recreational vehicles, a number of

sources are available for each vehicle type. 

For snowmobiles activity information is available from (a) studies on the economic

impact of snowmobile operation in seven states (12-18), (b) consumer-satisfaction survey results

from the snowmobile industry, and (c) snowmobile enthusiasts’ self-reported usage estimates

compiled and provided by the Bluewater Network (an environmental organization). These

sources presented usage information in terms of average or typical miles ridden per year. To

convert the mileage estimates to operating hours, we estimated the average speed for typical

snowmobile operation.

The information available on average speed was collected on instrumented machines

during development of an emissions test cycle for snowmobiles, performed by Southwest
1

 This memorandum supplements the Advance Notice of Proposed Rulemaking: Control of Emissions from

Nonroad Large Spark Ignition Engines, Recreational Engines (Marine and Land-based), and Highway Motorcycles

(November 20, 2000). See http://www.otaq.gov/otaq/recveh.htm.

11

Research Institute under sponsorship of the International Snowmobile Manufacturers Association

(11). The cycle development work encompassed operation over varied conditions, including

moderate and aggressive trail riding, lake riding, off-trail freestyle riding, and operation with

single and double riders. Sled speeds ranged from 14 to 32 mph, although the bulk of the data

falls between 20 and 30 mph. Because of the large variation in speed estimates, it is difficult to

determine what average speed is the most representative. We know that the correct speed is

somewhere within this range and that the mode of the estimates fell at the midpoint of the range. 

Therefore, we are using an average speed of 23 mph for snowmobile operation. We believe that

this value is reasonable and it is supported by the snowmobile manufacturers per a recent

discussion . 

 Having estimated average speed, it is possible to convert the estimated average yearly

mileage into yearly operating hours. The range of average yearly mileage estimates available to

us is 540 to 1,800 miles. Manufacturers have indicated that for winters with average or above

average snowfall, the average yearly mileage is approximately 1,500 miles and that for poorer

winters, with less than average snowfall, the average yearly mileage is approximately 1,200

miles. These estimates fall well within the range of estimates given above . In fact, several of

the state economic studies indicated that their estimates for mileage were low due to poor

snowfall during the winter in which they performed their studies. Therefore, we estimate the

average yearly travel distance for snowmobiles at 1,300 miles. Given an average speed of 23 mph

and an average mileage of 1,300 miles, we estimate the average yearly activity at 57 hours per

year. 

For snowmobiles, the load factor of 0.34 is derived from data collected during the cycle 

development project described above (11).

Based on data that has become available since the publication of the Proposed Rule for

control of emissions from recreational engines, we have revised the activity estimate for allterrain vehicles (ATVs). For reference, the prior estimate, which is superseded by the estimate

described in this report and referenced Rule documents, is presented and described in the docket

memorandum Emission Modeling for Recreational Vehicles (EPA420-F-00-051, Docket A-98-

01).1

Data sources used to derive the revised estimate include: (a) A phone survey sponsored

by Honda in which owners of TRX model utility ATVs were requested to report odometer and

hour-meter readings, (b) a database of warranty claim information provided by another

manufacturer, which included odometer and hour-meter readings, (c) a national survey of ATV

population and usage sponsored by the Consumer Product Safety Commission (20), and (d) a

“market panel” survey of ATV usage sponsored by major manufacturers. The manufacturers’
12

survey was performed during the same time period as the CPSC study, employed similar

interview methods and obtained very similar results. 

Based on these sources, ATV activity has been re-estimated at 1,570 miles/year. This

value is intended to represent a national annual average. and may be further revised following 

additional analyses in support of the rulemaking. For a more detailed description of the

derivation of this estimate and any minor updates to it, see the Final Regulatory Support

Document: Control of Emissions from Unregulated Nonroad Engines (21). 

 For off-road motorcycles, there are two sources of information on activity or usage rates. 

The first source is information provided by the Motorcycle Industry Council (MIC). MIC

periodically conducts surveys on motorcycle usage. . MIC uses two methods to estimate offroad motorcycle usage from the survey results. Method one is based on the results of a single

question that asks the respondent how many miles they rode in the last year. Method two is

based on the multiplication of the responses from three questions: (a) during how many months

of the year did the respondent ride?, (b) how many days during a typical month did the

respondent ride?, and (c) how many hours did the respondent ride in a typical day? The estimate

from method one is 222 miles per year and that from method two is 1,260 miles per year. MIC

has suggested that method one is the more appropriate estimate because method two may

compound any error that exists in the results of each of the three questions. We have concerns

with the results of the MIC survey because the values for method one and two are dramatically

different. Activity expressed in miles/year is consistent with corresponding emission factors for

off-road motorcycles, which are expressed in grams/mile.

The second source of information is a study done in 1994 by the Oak Ridge National

Laboratory (ORNL) titled, “Fuel Used for Off-Road Recreation” (22). This study estimated total

average fuel usage for off-road motorcycles at 59 gallons/year, which ORNL considers to be a

“medium” estimate. Recent data from California (), combined with older data collected at

Southwest Research Institute (SwRI) , suggest that the average fuel economy for off-road

motorcycles is approximately 50 miles per gallon (mpg), as tested over the Federal Test

Procedure (FTP) . This estimate may be too high for actual operation off-road, so we assume an

estimate of 40 mpg. By multiplying the annual average fuel usage by the average fuel economy,

we arrive at an estimate of approximately 2,400 miles per year.

Due to uncertainty related to interview methods in the MIC survey, we have estimated

motorcycle activity based on fuel use as estimated by ORNL, and fuel economy estimated in-use

and on the FTP, as described above. Thus, we estimate annual activity at 2,400 miles per year for

two and four-stroke off-road motorcycles. As of this writing, this estimate is under review and

may be revised to incorporate analyses supporting the final rule covering recreational vehicles.

For ATVs and off-road motorcycles, load factors are no longer necessary, since the

emission factors are expressed as grams per mile. As a result, for these equipment types, load

factors and average rated horsepowers are simply set to 1.0 in the input file. This modification
13

effectively converts the emissions calculation from a power-output basis to a distance-traveled

basis, similar to that used for cars and trucks. The operating hours, mileage, and load factors used

for recreational vehicles are listed in Table 8.

Table 8. Activity and Load Factors for Recreational Vehicles

Application Type Load Factor Hours per Year Mileage per Year

ATVs 2 & 4-stroke 1.0* ---- 1,570

Off-Road

Motorcycles

2 & 4-stroke 1.0* ---- 2,400

Snowmobiles 2-stroke 0.34 57 ----

* Average rated horsepower is also set at 1.0, effectively removing power output (rated power * load factor) from

the equation; emissions are thus calculated on the basis of EF*Act*Population, where units equal

g/mile*miles/year = g/year, which the model converts to tons/year.

Compression-Ignition (CI) Equipment

For CI equipment, we are using activity estimates from the 1998 PSR database.

The PSR CI load factors used in previous versions of NONROAD, which are based on

information obtained from surveys of equipment owners, have been replaced by load factors

obtained from actual engine testing over several transient cycles. The transient cycle

development and engine tests were conducted by Southwest Research Institute under contract to

EPA (with some of the cycle development work also co-sponsored by the Engine Manufacturers

Association) (23, 24, 25). Seven transient cycles were developed: agricultural tractor, backhoe

loader, crawler dozer, rubber-tire loader, skid-steer loader, arc welder, and excavator. For the

rubber-tire loader, skid-steer loader, and arc welder cycles, both “typical transient” and “high

transient” versions of the cycles were developed; for this work, the typical versions were used.

The load factors for the seven transient cycles are given in Table 9. The seven load

factors were further binned into three categories, “High,” “Low,” and “steady-state ” (represented

by an average of the seven cycles). . We consider this approach simpler and more defensible,

given the limited number of cycles designed to represent in-use operation for specific equipment

types and uncertainty in extrapolating the test data to broader equipment populations. This

approach is also consistent with that used to develop the new transient adjustment factors in the

model . The high load factor bin includes the following cycles: agricultural tractor (LF=0.78),

crawler dozer (LF=0.58), rubber-tire loader (LF=0.48), and excavator (LF=0.53). The low load

factor bin includes the remaining cycles: backhoe/loader (LF=0.21), skid-steer loader (LF=0.23),

and arc welder (LF=0.19). The “high” load factor cycles were averaged to obtain a composite

High LF (0.59). Similarly, the “low” load factor cycles were averaged to obtain a composite
14

Low LF (0.21). The load factors for all seven cycles were averaged to obtain a composite 7-cycle

average “steady-state” LF (0.43). See Table 9.

Table 9. Compression-Ignition Load Factors

Cycle Cycle Load Factors Assignment Average

Agricultural

Tractor

0.78

High 0.59 Crawler Dozer 0.58

Rubber-tired

Loader

0.48

Excavator 0.53

Backhoe

Loader

0.21

Low 0.21

Skid-steer

Loader

0.23

Arc Welder 0.19

7-cycle average --- Steady-state 0.43

Each diesel nonroad equipment type was assigned one of these three composite load

factors (Hi LF, Lo LF, or 7-cycle average). To apply these load factors, we matched nonroad

applications with the test cycle that most closely represents the nonroad activity for the

application. Table 10 lists the diesel nonroad applications used in the NONROAD model and the

load factor assignment considered representative of that application. If steady-state operation is

typical of an application, the 7-cycle average load factor was assigned.

The resulting load factors for each equipment type are provided in Appendix A.
15

Table 10. CI Load Factor Assignments by Equipment Type

SCC Equipment Type Representative

Cycle

Load Factor

Assignment

2270001000 Recreational Vehicles All Backhoe Lo LF

2270001020 Recreational Vehicles Snowmobiles None Avg 7-cycle

2270001030 Recreational Vehicles All Terrain Vehicles None Avg 7-cycle

2270001040 Recreational Vehicles Minibikes None Avg 7-cycle

2270001050 Recreational Vehicles Golf Carts None Avg 7-cycle

2270001060 Recreational Vehicles Speciality Vehicle Carts Backhoe Lo LF

2270002003 Construction Equipment Pavers Crawler Hi LF

2270002006 Construction Equipment Tampers/Rammers None Avg 7-cycle

2270002009 Construction Equipment Plate Compactors None Avg 7-cycle

2270002015 Construction Equipment Rollers Crawler Hi LF

2270002018 Construction Equipment Scrapers Crawler Hi LF

2270002021 Construction Equipment Paving Equipment Crawler Hi LF

2270002024 Construction Equipment Surfacing Equipment Crawler Hi LF

2270002027 Construction Equipment Signal Boards None Avg 7-cycle

2270002030 Construction Equipment Trenchers Crawler Hi LF

2270002033 Construction Equipment Bore/Drill Rigs None Avg 7-cycle

2270002036 Construction Equipment Excavators Excavator Hi LF

2270002039 Construction Equipment Concrete/Industrial Saws Crawler Hi LF

2270002042 Construction Equipment Cement & Mortar Mixers None Avg 7-cycle

2270002045 Construction Equipment Cranes None Avg 7-cycle

2270002048 Construction Equipment Graders Crawler Hi LF

2270002051 Construction Equipment Off-highway Trucks Crawler Hi LF

2270002054 Construction Equipment Crushing/Proc. Equipment None Avg 7-cycle

2270002057 Construction Equipment Rough Terrain Forklifts RTLoader Hi LF

2270002060 Construction Equipment Rubber Tire Loaders RTLoader Hi LF

2270002063 Construction Equipment Rubber Tire Dozers Crawler Hi LF

2270002066 Construction Equipment Tractors/Loaders/Backhoes Backhoe Lo LF

2270002069 Construction Equipment Crawler Dozer Crawler Hi LF

2270002072 Construction Equipment Skid Steer Loaders SSLoader Lo LF

2270002075 Construction Equipment Off-Highway Tractors Crawler Hi LF

2270002078 Construction Equipment Dumpers/Tenders Backhoe Lo LF

2270002081 Construction Equipment Other Construction Equipment Crawler Hi LF

2270003010 Industrial Equipment Aerial Lifts Backhoe Lo LF

2270003020 Industrial Equipment Forklifts RTLoader Hi LF

2270003030 Industrial Equipment Sweepers/Scrubbers None Avg 7-cycle

2270003040 Industrial Equipment Other General Industrial Equipment None Avg 7-cycle

2270003050 Industrial Equipment Other Material Handling Equipment Backhoe Lo LF

2270003060 Industrial Equipment AC\Refrigeration None Avg 7-cycle

2270003070 Terminal Tractors Crawler Hi LF

2270004000 Lawn & Garden Equipment ALL None Avg 7-cycle

2270004010 Lawn & Garden Equipment Lawn mowers (Residential) None Avg 7-cycle

2270004011 Lawn & Garden Equipment Lawn mowers (Commercial) None Avg 7-cycle

2270004015 Lawn & Garden Equipment Rotary Tillers < 6 HP None Avg 7-cycle

2270004016 Lawn & Garden Equipment Rotary Tillers < 6 HP None Avg 7-cycle

2270004020 Lawn & Garden Equipment Chain Saws < 6 HP None Avg 7-cycle

2270004021 Lawn & Garden Equipment Chain Saws < 6 HP None Avg 7-cycle
Table 10. CI Load Factor Assignments by Equipment Type

SCC Equipment Type Representative

Cycle

Load Factor

Assignment

16

2270004025 Lawn & Garden Equipment Trimmers/Edgers/Brush None Avg 7-cycle

2270004026 Lawn & Garden Equipment Trimmers/Edgers/Brush None Avg 7-cycle

2270004030 Lawn & Garden Equipment Leafblowers/Vacuums None Avg 7-cycle

2270004031 Lawn & Garden Equipment Leafblowers/Vacuums None Avg 7-cycle

2270004035 Lawn & Garden Equipment Snowblowers None Avg 7-cycle

2270004036 Lawn & Garden Equipment Snowblowers (Commercial) None Avg 7-cycle

2270004040 Lawn & Garden Equipment Rear Engine Riding Mowers None Avg 7-cycle

2270004041 Lawn & Garden Equipment Rear Engine Riding Mowers None Avg 7-cycle

2270004045 Lawn & Garden Equipment Front Mowers None Avg 7-cycle

2270004046 Lawn & Garden Equipment Front Mowers (Commercial) None Avg 7-cycle

2270004050 Lawn & Garden Equipment Shredders < 6 HP None Avg 7-cycle

2270004051 Lawn & Garden Equipment Shredders < 6 HP None Avg 7-cycle

2270004055 Lawn & Garden Equipment Lawn & Garden Tractors None Avg 7-cycle

2270004056 Lawn & Garden Equipment Lawn & Garden Tractors None Avg 7-cycle

2270004060 Lawn & Garden Equipment Wood Splitters None Avg 7-cycle

2270004061 Lawn & Garden Equipment Wood Splitters (Commercial) None Avg 7-cycle

2270004065 Lawn & Garden Equipment Chippers/Stump Grinders None Avg 7-cycle

2270004066 Lawn & Garden Equipment Chippers/Stump Grinders None Avg 7-cycle

2270004071 Lawn & Garden Equipment Commercial Turf Equipment None Avg 7-cycle

2270004075 Lawn & Garden Equipment Other Lawn & Garden None Avg 7-cycle

2270004076 Lawn & Garden Equipment Other Lawn & Garden None Avg 7-cycle

2270005010 Farm Equipment 2-Wheel Tractors AgTractor Hi LF

2270005015 Farm Equipment Agricultural Tractors AgTractor Hi LF

2270005020 Farm Equipment Combines AgTractor Hi LF

2270005025 Farm Equipment Balers AgTractor Hi LF

2270005030 Farm Equipment Agricultural Mowers AgTractor Hi LF

2270005035 Farm Equipment Sprayers AgTractor Hi LF

2270005040 Farm Equipment Tillers > 6 HP AgTractor Hi LF

2270005045 Farm Equipment Swathers AgTractor Hi LF

2270005050 Farm Equipment Hydro Power Units None Avg 7-cycle

2270005055 Farm Equipment Other Agricultural Equipment AgTractor Hi LF

2270005060 Farm Equipment Irrigation Sets None Avg 7-cycle

2270006000 Light Commercial ALL None Avg 7-cycle

2270006005 Light Commercial Generator Sets None Avg 7-cycle

2270006010 Light Commercial Pumps None Avg 7-cycle

2270006015 Light Commercial Air Compressors None Avg 7-cycle

2270006020 Light Commercial Gas Compressors None Avg 7-cycle

2270006025 Light Commercial Welders ArcWelder Lo LF

2270006030 Light Commercial Pressure Washers None Avg 7-cycle

2270007005 Logging Equipment Chain Saws > 6 HP RTLoader Hi LF

2270007010 Logging Equipment Shredders > 6 HP RTLoader Hi LF

2270007015 Logging Equipment Forest Equipment RTLoader Hi LF

2270008005 Airport Service Equipment Airport Support Equipment RTLoader Hi LF

2270009010 Other Underground Mining Equipment Backhoe Lo LF

2270010010 Other Oil Field Equipment None Avg 7-cycle

2282020005 Recreational Pleasure Craft, Inboards None Avg 7-cycle
Table 10. CI Load Factor Assignments by Equipment Type

SCC Equipment Type Representative

Cycle

Load Factor

Assignment

17

2282020010 Recreational Pleasure Craft, Outboards None Avg 7-cycle

2282020015 Recreational Pleasure Craft, Personal Water Craft None Avg 7-cycle

2282020025 Recreational Pleasure Craft, Sailboat Aux. Outboard None Avg 7-cycle

2285002015 Railway Maintenance Backhoe Lo LF

References

(1) U. S. EPA. "Growth and Scrappage Methodology Report for NONROAD," Office of

Transportation and Air Quality, Assessment & Standards Division. NONROAD

Technical Report NR-007a, May 2002.

(2) U. S. EPA. "Nonroad Engine Population Estimates," Office of Transportation and Air

Quality, Assessment & Standards Division. NONROAD Technical Report NR-006b,

May 2002.

(3) California Air Resources Board. (CARB). "Documentation of Input Factors for the New

Off-Road Mobile Source Emissions Inventory Model," Energy and Environmental

Analysis, Inc., February, 1997. Table 3-1, page ??.

(4) Energy and Environmental Analysis, Inc. "Documentation of Diesel Engine Life Values

Used in the ARB Off-Highway Model." Unpublished Report, prepared for U. S.

Environmental Protection Agency, Office of Transportation and Air Quality, September

2001. 

(5) U. S. Environmental Protection Agency. “Phase 2 Emission Standards for New

Nonhandheld Engines at or below 19 Kilowatts (kW).” Office of Mobile Sources,

Regulatory Impact Analysis, EPA420-R-99-003, March 1999.

(6) U. S. EPA. "Phase 2 Final Rule: Emission Standards for New Nonroad Handheld

Spark-Ignition Engines At or Below 19 Kilowatts." Office of Transportation and Air

Quality. Final Regulatory Impact Analysis, EPA420-R-00-004. March 2000. 

(7) Power Systems Research, Inc. "Reference Guide, U.S. PartsLink.” Edition 6.2 St. Paul,

MN. 

(8) E.H. Pechan & Associates. "Evaluation of Power Systems Research (PSR) Nonroad

Population Data Base," prepared for U.S. Environmental Protection Agency, Office of
2

 This memorandum supplements the Advance Notice of Proposed Rulemaking: Control of Emissions from

Nonroad Large Spark Ignition Engines, Recreational Engines (Marine and Land-based), and Highway Motorcycles

(November 20, 2000). See http://www.otaq.gov/otaq/recveh.htm.

18

Mobile Sources. EPA Contract No. 68-D3-0035, Work Assignment No. III-107, Pechan

Report No. 97.09.003/1807. September, 1997.

(9) United States Environmental Protection Agency. “Median Life, Annual Activity, and

Load Factor Values for Nonroad Engine Emissions Modeling,” Office of Mobile Sources,

Assessment & Modeling Division. NONROAD Technical Report NR-005A. June 15,

1998.

(10) United States Environmental Protection Agency. “Regulatory Impact Analysis: Control of

Air Pollution Emission Standards for New Nonroad Spark-Ignition Marine Engines."

Office of Air and Radiation. ANR-443. June 1996.

(11) United States Environmental Protection Agency. “Emission Modeling for Recreational

Vehicles,” Memorandum to Public Docket A-98-01. EPA420-F-00-051, November 13,

2000. 2

(12) Mc Elvany, Norman D. 1995. Snowmobiling in Vermont: An Economic Study and

Snowmobile User Survey. Johnson State College, Johnson, VT. Prepared for Vermont

Association of Snow Travelers (VAST).

(13) Robertson, Robert A. Assessment of Snowmobiling in New Hampshire "1996:" Summary

and Recommendations. Tourism Planning and Development Program, Department of

Resource Economics and Development, University of New Hampshire, Durham.

Prepared for the New Hampshire Snowmobile Association. August, 1996.

(14) Sylvester, James T. Snowmobile Gasoline Usage in Montana. Bureau of Business and

Economic Research, University of Montana, Missoula. Prepared for Montana

Department of Fish, Wildlife and Parks, and Montana Snowmobile Association.

September 28, 1996.

(15) Reiling, Stephen; Kotchen, Matthew; Kezis, Alan. An Economic Evaluation of

Snowmobiling in Maine. Department of Resource Economics and Policy, University of

Maine, Orono. Maine Agricultural and Forest Experiment Station No. 2069. Prepared for

the Maine Snowmobile Association. January, 1997.

(16) Nelson, Charles M., Lynch, Joel A., Stynes, Daniel J. An Assessment of Snowmobiling

in Michigan by Snowmobilers with Michigan Trail Permits. Department of Park,

Recreation and Tourism Resources, Michigan State University, East Lansing. Prepared
19

for Michigan Department of Natural Resources, Forest Management Division. February

10, 1998.

(17) Merwin Rural Services Institute. Snowmobiling in New York: An Analysis of Economic

Impact and Overview of the Industry in the Empire State. State University of New York,

Potsdam. Prepared for New York State Snowmobile Association, Inc. April, 1998.

(18) Loomis, David K; Lundrigan, Heather. 1999 Assessment of Snowmobiling in

Massachusetts. Human Dimensions Research Unit, Department of Natural Resources

Conservation University of Massachusetts, Amherst. Prepared for Snowmobiling

Association of Massachusetts. March 30, 2000.

(19) United States Environmental Protection Agency. “Draft Regulatory Support Document:

Control of Emissions from Nonroad Large Spark Ignition Engines, Recreational Engines

(Marine and Land-based), and Highway Motorcycles.” Office of Transportation & Air

Quality, Assessment & Standards Division. EPA420-D-01-004, September 2001.

(20) United States Consumer Product Safety Commission. “Report on 1997 ATV Exposure

Survey.” Directorate for Economic Analysis, Bethesda, Maryland. April 1998. 

(21) United States Environmental Protection Agency. "Final Regulatory Support Document:

Control of Emissions from Unregulated Nonroad Engines." EPA420-R-02-022,

September 2002.

(22) Oak Ridge National Laboratory. “Fuel Used for Off-Highway Recreation” Center for

Transportation Analysis, Statistics and Data Analysis Group. ORNL-6794. July, 1994.

(23) Fritz, S.G. and M.E. Starr, “Emission Factors for Compression Ignition Nonroad Engines

Operated on Number 2 Highway and Nonroad Diesel Fuel,” Southwest Research

Institute. SwRI 08-7601-822, March 1998.

(24) Starr, Michael E., “Nonroad Engine Emissions Testing,” Southwest Research Institute. 

SwRI ???-??? September 1999.

(25) Starr, Michael E., “Excavator Cycle Development,” Southwest Research Institute. SwRI

2206-801, September 1999.
20
21

Appendix A

Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

2260001010 2-Stroke Motorcycles: Off-Road 1.00 2400*

2260001020 2-Stroke Snowmobiles 0.34 57

2260001030 2-Stroke All Terrain Vehicles 1.00 7000*

2260001050 2-Stroke Golf Carts 0.46 1080

2260001060 2-Stroke Specialty Vehicle Carts 0.58 65

2260002003 2-Stroke Asphalt Pavers 0.66 392

2260002006 2-Stroke Tampers/Rammers 0.55 160

2260002009 2-Stroke Plate Compactors 0.55 166

2260002012 2-Stroke Concrete Pavers 0.55 0

2260002015 2-Stroke Rollers 0.62 621

2260002018 2-Stroke Scrapers 0.70 540

2260002021 2-Stroke Paving Equipment 0.59 175

2260002024 2-Stroke Surfacing Equipment 0.49 488

2260002027 2-Stroke Signal Boards 0.72 318

2260002030 2-Stroke Trenchers 0.66 402

2260002033 2-Stroke Bore/Drill Rigs 0.79 107

2260002036 2-Stroke Excavators 0.53 378

2260002039 2-Stroke Concrete/Industrial Saws 0.78 610

2260002042 2-Stroke Cement & Mortar Mixers 0.59 84

2260002045 2-Stroke Cranes 0.47 415

2260002048 2-Stroke Graders 0.64 504

2260002051 2-Stroke Off-highway Trucks 0.80 450

2260002054 2-Stroke Crushing/Proc. Equipment 0.85 241

2260002057 2-Stroke Rough Terrain Forklifts 0.63 413

2260002060 2-Stroke Rubber Tire Loaders 0.71 512

2260002063 2-Stroke Rubber Tire Dozers 0.75 900

2260002066 2-Stroke Tractors/Loaders/Backhoes 0.48 870

2260002069 2-Stroke Crawler Dozer 0.80 700

2260002072 2-Stroke Skid Steer Loaders 0.58 310

2260002075 2-Stroke Off-Highway Tractors 0.70 155

2260002078 2-Stroke Dumpers/Tenders 0.41 127

2260002081 2-Stroke Other Construction Equipment 0.48 371

2260003010 2-Stroke Aerial Lifts 0.46 361

2260003020 2-Stroke Forklifts 0.30 1800

2260003030 2-Stroke Sweepers/Scrubbers 0.71 516

2260003040 2-Stroke Other General Industrial Equipment 0.54 713

2260003050 2-Stroke Other Material Handling Equipment 0.53 386

2260003060 2-Stroke Refrigeration 0.46 605

2260003070 2-Stroke Terminal Tractors 0.78 827

2260004010 2-Stroke Lawn mowers (Residential) 0.33 25

2260004011 2-Stroke Lawn mowers (Commercial) 0.33 406

2260004015 2-Stroke Rotary Tillers < 6 HP (Residential) 0.40 17

2260004016 2-Stroke Rotary Tillers < 6 HP (Commercial) 0.40 472

2260004020 2-Stroke Chain Saws < 6 HP (Residential) 0.70 13

2260004021 2-Stroke Chain Saws < 6 HP (Commercial) 0.70 303

2260004025 2-Stroke Trimmers/Edgers/Brush Cutters 0.91 9

2260004026 2-Stroke Trimmers/Edgers/Brush Cutters 0.91 137

2260004030 2-Stroke Leafblowers/Vacuums (Residential) 0.94 10

2260004031 2-Stroke Leafblowers/Vacuums (Commercial) 0.94 282
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

22

2260004035 2-Stroke Snowblowers (Residential) 0.35 8

2260004036 2-Stroke Snowblowers (Commercial) 0.35 136

2260004040 2-Stroke Rear Engine Riding Mowers (Res.) 0.38 36

2260004041 2-Stroke Rear Engine Riding Mowers (Comm.) 0.38 569

2260004045 2-Stroke Front Mowers (Residential) 0.65 86

2260004046 2-Stroke Front Mowers (Commercial) 0.65 86

2260004050 2-Stroke Shredders < 6 HP (Residential) 0.80 50

2260004051 2-Stroke Shredders < 6 HP (Commercial) 0.80 50

2260004055 2-Stroke Lawn & Garden Tractors (Residential) 0.44 45

2260004056 2-Stroke Lawn & Garden Tractors (Commercial) 0.44 721

2260004060 2-Stroke Wood Splitters (Residential) 0.69 76

2260004061 2-Stroke Wood Splitters (Commercial) 0.69 76

2260004065 2-Stroke Chippers/Stump Grinders (Res.) 0.78 488

2260004066 2-Stroke Chippers/Stump Grinders (Comm.) 0.78 488

2260004070 2-Stroke Commercial Turf Equipment (Res.) 0.60 682

2260004071 2-Stroke Commercial Turf Equipment (Comm) 0.60 682

2260004075 2-Stroke Other Lawn & Garden Equipment 0.58 61

2260004076 2-Stroke Other Lawn & Garden Equipment 0.58 61

2260005010 2-Stroke 2-Wheel Tractors 0.62 286

2260005015 2-Stroke Agricultural Tractors 0.62 550

2260005020 2-Stroke Combines 0.74 125

2260005025 2-Stroke Balers 0.62 68

2260005030 2-Stroke Agricultural Mowers 0.48 175

2260005035 2-Stroke Sprayers 0.65 80

2260005040 2-Stroke Tillers > 6 HP 0.71 43

2260005045 2-Stroke Swathers 0.52 95

2260005050 2-Stroke Hydro Power Units 0.56 450

2260005055 2-Stroke Other Agricultural Equipment 0.55 124

2260005060 2-Stroke Irrigation Sets 0.60 716

2260006005 2-Stroke Light Commercial Generator Set 0.68 115

2260006010 2-Stroke Light Commercial Pumps 0.69 221

2260006015 2-Stroke Light Commercial Air Compressors 0.56 484

2260006020 2-Stroke Light Commercial Gas Compressors 0.85 6000

2260006025 2-Stroke Light Commercial Welders 0.68 408

2260006030 2-Stroke Light Commercial Pressure Wash 0.85 115

2260007005 2-Stroke Logging Equipment Chain Saws > 6 HP 0.70 303

2260007010 2-Stroke Logging Equipment Shredders > 6 HP 0.80 50

2260007015 2-Stroke Logging Equipment Skidders 0.70 350

2260007020 2-Stroke Logging Equipment Fellers/Bunchers 0.70 0

2260008005 2-Stroke Airport Support Equipment 0.56 681

2260009010 2-Stroke Other Underground Mining Equipment 0.80 260

2260010010 2-Stroke Other Oil Field Equipment 0.90 1104

2265001010 4-Stroke Motorcycles: Off-Road 1.00 2400

2265001020 4-Stroke Snowmobiles 0.34 57

2265001030 4-Stroke All Terrain Vehicles 1.00 7000

2265001050 4-Stroke Golf Carts 0.46 1080

2265001060 4-Stroke Specialty Vehicle Carts 0.58 65

2265002003 4-Stroke Asphalt Pavers 0.66 392

2265002006 4-Stroke Tampers/Rammers 0.55 160

2265002009 4-Stroke Plate Compactors 0.55 166

2265002012 4-Stroke Concrete Pavers 0.55 0

2265002015 4-Stroke Rollers 0.62 621
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

23

2265002018 4-Stroke Scrapers 0.70 540

2265002021 4-Stroke Paving Equipment 0.59 175

2265002024 4-Stroke Surfacing Equipment 0.49 488

2265002027 4-Stroke Signal Boards 0.72 318

2265002030 4-Stroke Trenchers 0.66 402

2265002033 4-Stroke Bore/Drill Rigs 0.79 107

2265002036 4-Stroke Excavators 0.53 378

2265002039 4-Stroke Concrete/Industrial Saws 0.78 610

2265002042 4-Stroke Cement & Mortar Mixers 0.59 84

2265002045 4-Stroke Cranes 0.47 415

2265002048 4-Stroke Graders 0.64 504

2265002051 4-Stroke Off-highway Trucks 0.80 450

2265002054 4-Stroke Crushing/Proc. Equipment 0.85 241

2265002057 4-Stroke Rough Terrain Forklifts 0.63 413

2265002060 4-Stroke Rubber Tire Loaders 0.71 512

2265002063 4-Stroke Rubber Tire Dozers 0.75 900

2265002066 4-Stroke Tractors/Loaders/Backhoes 0.48 870

2265002069 4-Stroke Crawler Tractors 0.80 700

2265002072 4-Stroke Skid Steer Loaders 0.58 310

2265002075 4-Stroke Off-Highway Tractors 0.70 155

2265002078 4-Stroke Dumpers/Tenders 0.41 127

2265002081 4-Stroke Other Construction Equipment 0.48 371

2265003010 4-Stroke Aerial Lifts 0.46 361

2265003020 4-Stroke Forklifts 0.30 1800

2265003030 4-Stroke Sweepers/Scrubbers 0.71 516

2265003040 4-Stroke Other General Industrial Equipment 0.54 713

2265003050 4-Stroke Other Material Handling Equipment 0.53 386

2265003060 4-Stroke Industial AC\Refrigeration 0.46 605

2265003070 4-Stroke Terminal Tractors 0.78 827

2265004010 4-Stroke Lawn mowers (Residential) 0.33 25

2265004011 4-Stroke Lawn mowers (Commercial) 0.33 406

2265004015 4-Stroke Rotary Tillers < 6 HP (Residential) 0.40 17

2265004016 4-Stroke Rotary Tillers < 6 HP (Commercial) 0.40 472

2265004020 4-Stroke Chain Saws < 6 HP (Residential) 0.70 13

2265004021 4-Stroke Chain Saws < 6 HP (Commercial) 0.70 303

2265004025 4-Stroke Trimmers/Edgers/Brush Cutters 0.91 9

2265004026 4-Stroke Trimmers/Edgers/Brush Cutters 0.91 137

2265004030 4-Stroke Leafblowers/Vacuums (Residential) 0.94 10

2265004031 4-Stroke Leafblowers/Vacuums (Commercial) 0.94 282

2265004035 4-Stroke Snowblowers (Residential) 0.35 8

2265004036 4-Stroke Snowblowers (Commercial) 0.35 136

2265004040 4-Stroke Rear Engine Riding Mowers (Res.) 0.38 36

2265004041 4-Stroke Rear Engine Riding Mowers (Comm) 0.38 569

2265004045 4-Stroke Front Mowers (Residential) 0.65 86

2265004046 4-Stroke Front Mowers (Commercial) 0.65 86

2265004050 4-Stroke Shredders < 6 HP (Residential) 0.80 50

2265004051 4-Stroke Shredders < 6 HP (Commercial) 0.80 50

2265004055 4-Stroke Lawn & Garden Tractors (Residential) 0.44 45

2265004056 4-Stroke Lawn & Garden Tractors (Commercial) 0.44 721

2265004060 4-Stroke Wood Splitters (Residential) 0.69 76

2265004061 4-Stroke Wood Splitters (Commercial) 0.69 76

2265004065 4-Stroke Chippers/Stump Grinders (Res.) 0.78 488
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

24

2265004066 4-Stroke Chippers/Stump Grinders (Comm.) 0.78 488

2265004070 4-Stroke Commercial Turf Equipment (Res.) 0.60 682

2265004071 4-Stroke Commercial Turf Equipment (Comm) 0.60 682

2265004075 4-Stroke Other Lawn & Garden Equipment 0.58 61

2265004076 4-Stroke Other Lawn & Garden Equipment 0.58 61

2265005010 4-Stroke 2-Wheel Tractors 0.62 286

2265005015 4-Stroke Agricultural Tractors 0.62 550

2265005020 4-Stroke Combines 0.74 125

2265005025 4-Stroke Balers 0.62 68

2265005030 4-Stroke Agricultural Mowers 0.48 175

2265005035 4-Stroke Sprayers 0.65 80

2265005040 4-Stroke Tillers > 5 HP 0.71 43

2265005045 4-Stroke Swathers 0.52 95

2265005050 4-Stroke Hydro Power Units 0.56 450

2265005055 4-Stroke Other Agricultural Equipment 0.55 124

2265005060 4-Stroke Irrigation Sets 0.60 716

2265006005 4-Stroke Light Commercial Generator Sets 0.68 115

2265006010 4-Stroke Light Commercial Pumps 0.69 221

2265006015 4-Stroke Light Commercial Air Compressors 0.56 484

2265006020 4-Stroke Light Commercial Gas Compressors 0.85 6000

2265006025 4-Stroke Light Commercial Welders 0.68 408

2265006030 4-Stroke Light Commercial Pressure Washers 0.85 115

2265007005 4-Stroke Logging Equipment Chain Saws > 6 HP 0.70 303

2265007010 4-Stroke Logging Equipment Shredders > 6 HP 0.80 50

2265007015 4-Stroke Logging Equipment Skidders 0.70 350

2265007020 4-Stroke Logging Equipment Fellers/Bunchers 0.70 0

2265008005 4-Stroke Airport Support Equipment 0.56 681

2265009010 4-Stroke Other Underground Mining Equipment 0.80 260

2265010010 4-Stroke Other Oil Field Equipment 0.90 1104

2270001020 Diesel Snowmobiles (unused) 0.34 40

2270001030 Diesel All Terrain Vehicles/MC (unused) 0.42 0

2270001050 Diesel Golf Carts (unused) 0.49 1150

2270001060 Diesel Specialty Vehicle Carts 0.21 435

2270002003 Diesel Pavers 0.59 821

2270002006 Diesel Tampers/Rammers (unused) 0.43 460

2270002009 Diesel Plate Compactors 0.43 484

2270002012 Diesel Concrete Pavers (unused) 0.59 0

2270002015 Diesel Rollers 0.59 760

2270002018 Diesel Scrapers 0.59 914

2270002021 Diesel Paving Equipment 0.59 622

2270002024 Diesel Surfacing Equipment 0.59 561

2270002027 Diesel Signal Boards 0.43 535

2270002030 Diesel Trenchers 0.59 593

2270002033 Diesel Bore/Drill Rigs 0.43 466

2270002036 Diesel Excavators 0.59 1092

2270002039 Diesel Concrete/Industrial Saws 0.59 580

2270002042 Diesel Cement & Mortar Mixers 0.43 275

2270002045 Diesel Cranes 0.43 990

2270002048 Diesel Graders 0.59 962

2270002051 Diesel Off-highway Trucks 0.59 1641

2270002054 Diesel Crushing/Proc. Equipment 0.43 955

2270002057 Diesel Rough Terrain Forklifts 0.59 662
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

25

2270002060 Diesel Rubber Tire Loaders 0.59 761

2270002063 Diesel Rubber Tire Dozers 0.59 899

2270002066 Diesel Tractors/Loaders/Backhoes 0.21 1135

2270002069 Diesel Crawler Tractors 0.59 936

2270002072 Diesel Skid Steer Loaders 0.21 818

2270002075 Diesel Off-Highway Tractors 0.59 855

2270002078 Diesel Dumpers/Tenders 0.21 566

2270002081 Diesel Other Construction Equipment 0.59 606

2270003010 Diesel Aerial Lifts 0.21 384

2270003020 Diesel Forklifts 0.59 1700

2270003030 Diesel Sweepers/Scrubbers 0.43 1220

2270003040 Diesel Other General Industrial Equipment 0.43 878

2270003050 Diesel Other Material Handling Equipment 0.21 421

2270003060 Diesel AC\Refrigeration 0.43 1341

2270003070 Diesel Terminal Tractors 0.59 1257

2270004010 Diesel Lawn mowers (Residential) 0.43 320

2270004011 Diesel Lawn mowers (Commerical) 0.43 320

2270004015 Diesel Rotary Tillers < 6 HP (Residential) 0.43 172

2270004016 Diesel Rotary Tillers < 6 HP (Commercial) 0.43 172

2270004020 Diesel Chain Saws < 6 HP (Residential) 0.43 70

2270004021 Diesel Chain Saws < 6 HP (Commercial) 0.43 70

2270004025 Diesel Trimmers/Edgers/Brush Cutters (Res.) 0.43 60

2270004026 Diesel Trimmers/Edgers/Brush Cutters (Comm.) 0.43 60

2270004030 Diesel Leafblowers/Vacuums (Residential) 0.43 120

2270004031 Diesel Leafblowers/Vacuums (Commercial) 0.43 120

2270004035 Diesel Snowblowers (Residential) 0.43 400

2270004036 Diesel Snowblowers (Commercial) 0.43 400

2270004040 Diesel Rear Engine Riding Mowers (Res.) 0.43 480

2270004041 Diesel Rear Engine Riding Mowers (Comm.) 0.43 480

2270004045 Diesel Front Mowers (Residential) 0.43 480

2270004046 Diesel Front Mowers (Commercial) 0.43 480

2270004050 Diesel Shredders < 6 HP (Residential) 0.43 120

2270004051 Diesel Shredders < 6 HP (Commercial) 0.43 120

2270004055 Diesel Lawn & Garden Tractors (Residential) 0.43 544

2270004056 Diesel Lawn & Garden Tractors (Commercial) 0.43 544

2270004060 Diesel Wood Splitters (Residential) 0.43 265

2270004061 Diesel Wood Splitters (Commercial) 0.43 265

2270004065 Diesel Chippers/Stump Grinders (Residential) 0.43 465

2270004066 Diesel Chippers/Stump Grinders (Commercial) 0.43 465

2270004070 Diesel Commercial Turf Equipment (Res.) 0.43 1068

2270004071 Diesel Commercial Turf Equipment (Comm.) 0.43 1068

2270004075 Diesel Other Lawn & Garden Equipment (Res.) 0.43 433

2270004076 Diesel Other Lawn & Garden Equipment (Comm.) 0.43 433

2270005010 Diesel 2-Wheel Tractors 0.59 544

2270005015 Diesel Agricultural Tractors 0.59 475

2270005020 Diesel Combines 0.59 150

2270005025 Diesel Balers 0.59 95

2270005030 Diesel Agricultural Mowers 0.59 363

2270005035 Diesel Sprayers 0.59 90

2270005040 Diesel Tillers > 6 HP 0.59 172

2270005045 Diesel Swathers 0.59 110

2270005050 Diesel Hydro Power Units 0.43 790
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

26

2270005055 Diesel Other Agricultural Equipment 0.59 381

2270005060 Diesel Irrigation Sets 0.43 749

2270006005 Diesel Light Commercial Generator Sets 0.43 338

2270006010 Diesel Light Commercial Pumps 0.43 403

2270006015 Diesel Light Commercial Air Compressors 0.43 815

2270006020 Diesel Light Commercial Gas Compressors 0.43 8500

2270006025 Diesel Light Commercial Welders 0.21 643

2270006030 Diesel Light Commercial Pressure Washer 0.43 145

2270007005 Diesel Logging Equipment Chain Saws > 6 HP 0.59 70

2270007010 Diesel Logging Equipment Shredders > 6 HP 0.59 120

2270007015 Diesel Logging Equip Fell/Bunch/Skidders 0.59 1276

2270007020 Diesel Logging Equip Fell/Bunch (unused) 0.59 0

2270008005 Diesel Airport Support Equipment 0.59 732

2270009010 Diesel Other Underground Mining Equipment 0.21 1533

2270010010 Diesel Other Oil Field Equipment 0.43 1231

2267001020 LPG Snowmobiles 0.34 40

2267001030 LPG All Terrain Vehicles/MC 0.42 63

2267001050 LPG Golf Carts 0.46 1080

2267001060 LPG Specialty Vehicle Carts 0.58 65

2267002003 LPG Asphalt Pavers 0.66 392

2267002006 LPG Tampers/Rammers 0.55 160

2267002009 LPG Plate Compactors 0.55 166

2267002012 LPG Concrete Pavers 0.55 0

2267002015 LPG Rollers 0.62 621

2267002018 LPG Scrapers 0.70 540

2267002021 LPG Paving Equipment 0.59 175

2267002024 LPG Surfacing Equipment 0.49 488

2267002027 LPG Signal Boards 0.72 318

2267002030 LPG Trenchers 0.66 402

2267002033 LPG Bore/Drill Rigs 0.79 107

2267002036 LPG Excavators 0.59 378

2267002039 LPG Concrete/Industrial Saws 0.78 610

2267002042 LPG Cement & Mortar Mixers 0.59 84

2267002045 LPG Cranes 0.47 415

2267002048 LPG Graders 0.64 504

2267002051 LPG Off-highway Trucks 0.80 450

2267002054 LPG Crushing/Proc. Equipment 0.85 241

2267002057 LPG Rough Terrain Forklifts 0.63 413

2267002060 LPG Rubber Tire Loaders 0.71 512

2267002063 LPG Rubber Tire Dozers 0.75 900

2267002066 LPG Tractors/Loaders/Backhoes 0.48 870

2267002069 LPG Crawler Tractors 0.80 700

2267002072 LPG Skid Steer Loaders 0.58 310

2267002075 LPG Off-Highway Tractors 0.70 155

2267002078 LPG Dumpers/Tenders 0.41 127

2267002081 LPG Other Construction Equipment 0.48 371

2267003010 LPG Aerial Lifts 0.46 361

2267003020 LPG Forklifts 0.30 1800

2267003030 LPG Sweepers/Scrubbers 0.71 516

2267003040 LPG Other General Industrial Equipment 0.54 713

2267003050 LPG Other Material Handling Equipment 0.53 386

2267003060 LPG AC\Refrigeration 0.46 605
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

27

2267003070 LPG Terminal Tractors 0.78 827

2267004010 LPG Lawn mowers (Residential) 0.33 25

2267004011 LPG Lawn mowers (Commercial) 0.33 406

2267004015 LPG Rotary Tillers < 6 HP (Residential) 0.40 17

2267004016 LPG Rotary Tillers < 6 HP (Commercial) 0.40 472

2267004020 LPG Chain Saws < 6 HP (Residential) 0.70 13

2267004021 LPG Chain Saws < 6 HP (Commercial) 0.70 303

2267004025 LPG Trimmers/Edgers/Brush Cutters (Res.) 0.91 9

2267004026 LPG Trimmers/Edgers/Brush Cutters (Comm.) 0.91 137

2267004030 LPG Leafblowers/Vacuums (Residential) 0.94 10

2267004031 LPG Leafblowers/Vacuums (Commercial) 0.94 282

2267004035 LPG Snowblowers (Residential) 0.35 8

2267004036 LPG Snowblowers (Commercial) 0.35 136

2267004040 LPG Rear Engine Riding Mowers (Residential) 0.38 36

2267004041 LPG Rear Engine Riding Mowers (Commercial) 0.38 569

2267004045 LPG Front Mowers (Residential) 0.65 86

2267004046 LPG Front Mowers (Commercial) 0.65 86

2267004050 LPG Shredders < 6 HP (Residential) 0.80 50

2267004051 LPG Shredders < 6 HP (Commercial) 0.80 50

2267004055 LPG Lawn & Garden Tractors (Residential) 0.44 45

2267004056 LPG Lawn & Garden Tractors (Commercial) 0.44 721

2267004060 LPG Wood Splitters (Residential) 0.69 76

2267004061 LPG Wood Splitters (Commercial) 0.69 76

2267004065 LPG Chippers/Stump Grinders (Residential) 0.78 488

2267004066 LPG Chippers/Stump Grinders (Commercial) 0.78 488

2267004070 LPG Commercial Turf Equipment (Residential) 0.60 682

2267004071 LPG Commercial Turf Equipment (Commercial) 0.60 682

2267004075 LPG Other Lawn & Garden Equipment (Res.) 0.58 61

2267004076 LPG Other Lawn & Garden Equipment (Comm.) 0.58 61

2267005010 LPG 2-Wheel Tractors 0.62 286

2267005015 LPG Agricultural Tractors 0.62 550

2267005020 LPG Combines 0.74 125

2267005025 LPG Balers 0.62 68

2267005030 LPG Agricultural Mowers 0.48 175

2267005035 LPG Sprayers 0.65 80

2267005040 LPG Tillers > 6 HP 0.71 43

2267005045 LPG Swathers 0.52 95

2267005050 LPG Hydro Power Units 0.56 450

2267005055 LPG Other Agricultural Equipment 0.55 124

2267005060 LPG Irrigation Sets 0.60 716

2267006005 LPG Light Commercial Generator Sets 0.68 115

2267006010 LPG Light Commercial Pumps 0.69 221

2267006015 LPG Light Commercial Air Compressors 0.56 484

2267006020 LPG Light Commercial Gas Compressors 0.85 6000

2267006025 LPG Light Commercial Welders 0.68 408

2267006030 LPG Light Commercial Pressure Washers 0.85 115

2267007005 LPG Logging Equipment Chain Saws > 6 HP 0.70 303

2267007010 LPG Logging Equipment Shredders > 6 HP 0.80 50

2267007015 LPG Logging Equipment Skidders 0.70 350

2267007020 LPG Logging Equipment Fellers/Bunchers 0.70 0

2267008005 LPG Airport Support Equipment 0.56 681

2267009010 LPG Other Underground Mining Equipment 0.80 260
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

28

2267010010 LPG Other Oil Field Equipment 0.90 1104

2268001020 CNG Snowmobiles 0.34 40

2268001030 CNG All Terrain Vehicles/MC 0.42 63

2268001050 CNG Golf Carts 0.46 1080

2268001060 CNG Specialty Vehicle Carts 0.58 65

2268002003 CNG Asphalt Pavers 0.66 392

2268002006 CNG Tampers/Rammers 0.55 160

2268002009 CNG Plate Compactors 0.55 166

2268002012 CNG Concrete Pavers 0.55 0

2268002015 CNG Rollers 0.62 621

2268002018 CNG Scrapers 0.70 540

2268002021 CNG Paving Equipment 0.59 175

2268002024 CNG Surfacing Equipment 0.49 488

2268002027 CNG Signal Boards 0.72 318

2268002030 CNG Trenchers 0.66 402

2268002033 CNG Bore/Drill Rigs 0.79 107

2268002036 CNG Excavators 0.53 378

2268002039 CNG Concrete/Industrial Saws 0.78 610

2268002042 CNG Cement & Mortar Mixers 0.59 84

2268002045 CNG Cranes 0.47 415

2268002048 CNG Graders 0.64 504

2268002051 CNG Off-highway Trucks 0.80 450

2268002054 CNG Crushing/Proc. Equipment 0.85 241

2268002057 CNG Rough Terrain Forklifts 0.63 413

2268002060 CNG Rubber Tire Loaders 0.71 512

2268002063 CNG Rubber Tire Dozers 0.75 900

2268002066 CNG Tractors/Loaders/Backhoes 0.48 870

2268002069 CNG Crawler Tractors 0.80 700

2268002072 CNG Skid Steer Loaders 0.58 310

2268002075 CNG Off-Highway Tractors 0.70 155

2268002078 CNG Dumpers/Tenders 0.41 127

2268002081 CNG Other Construction Equipment 0.48 371

2268003010 CNG Aerial Lifts 0.46 361

2268003020 CNG Forklifts 0.30 1800

2268003030 CNG Sweepers/Scrubbers 0.71 516

2268003040 CNG Other General Industrial Equipment 0.54 713

2268003050 CNG Other Material Handling Equipment 0.53 386

2268003060 CNG AC\Refrigeration 0.46 605

2268003070 CNG Terminal Tractors 0.78 827

2268004010 CNG Lawn mowers (Residential) 0.33 25

2268004011 CNG Lawn mowers (Commercial) 0.33 406

2268004015 CNG Rotary Tillers < 6 HP (Residential) 0.40 17

2268004016 CNG Rotary Tillers < 6 HP (Commercial) 0.40 472

2268004020 CNG Chain Saws < 6 HP (Residential) 0.70 13

2268004021 CNG Chain Saws < 6 HP (Commercial) 0.70 303

2268004025 CNG Trimmers/Edgers/Brush Cutters (Res.) 0.91 9

2268004026 CNG Trimmers/Edgers/Brush Cutters (Comm.) 0.91 137

2268004030 CNG Leafblowers/Vacuums (Residential) 0.94 10

2268004031 CNG Leafblowers/Vacuums (Commercial) 0.94 282

2268004035 CNG Snowblowers (Residential) 0.35 8

2268004036 CNG Snowblowers (Commercial) 0.35 136

2268004040 CNG Rear Engine Riding Mowers (Residential) 0.38 36
Load Factor and Activity Estimates in Draft NONROAD2002

SCC Equipment Description Load Factor

(fraction of power)

Activity

(hours/year)

29

2268004041 CNG Rear Engine Riding Mowers (Commercial) 0.38 569

2268004045 CNG Front Mowers (Residential) 0.65 86

2268004046 CNG Front Mowers (Commercial) 0.65 86

2268004050 CNG Shredders < 6 HP (Residential) 0.80 50

2268004051 CNG Shredders < 6 HP (Commercial) 0.80 50

2268004055 CNG Lawn & Garden Tractors (Residential) 0.44 45

2268004056 CNG Lawn & Garden Tractors (Commercial) 0.44 721

2268004060 CNG Wood Splitters (Residential) 0.69 76

2268004061 CNG Wood Splitters (Commercial) 0.69 76

2268004065 CNG Chippers/Stump Grinders (Residential) 0.78 488

2268004066 CNG Chippers/Stump Grinders (Commercial) 0.78 488

2268004070 CNG Commercial Turf Equipment (Residential) 0.60 682

2268004071 CNG Commercial Turf Equipment (Commercial) 0.60 682

2268004075 CNG Other Lawn & Garden Equipment (Res.) 0.58 61

2268004076 CNG Other Lawn & Garden Equipment (Comm.) 0.58 61

2268005010 CNG 2-Wheel Tractors 0.62 286

2268005015 CNG Agricultural Tractors 0.62 550

2268005020 CNG Combines 0.74 125

2268005025 CNG Balers 0.62 68

2268005030 CNG Agricultural Mowers 0.48 175

2268005035 CNG Sprayers 0.65 80

2268005040 CNG Tillers > 6 HP 0.71 43

2268005045 CNG Swathers 0.52 95

2268005050 CNG Hydro Power Units 0.56 450

2268005055 CNG Other Agricultural Equipment 0.55 124

2268005060 CNG Irrigation Sets 0.60 716

2268006005 CNG Light Commercial Generator Sets 0.68 115

2268006010 CNG Light Commercial Pumps 0.69 221

2268006015 CNG Light Commercial Air Compressors 0.56 484

2268006020 CNG Light Commercial Gas Compressors 0.85 6000

2268006025 CNG Light Commercial Welders 0.68 408

2268006030 CNG Light Commercial Pressure Washers 0.85 115

2268007005 CNG Logging Equipment Chain Saws > 6 HP 0.70 303

2268007010 CNG Logging Equipment Shredders > 6 HP 0.80 50

2268007015 CNG Logging Equipment Skidders 0.70 350

2268007020 CNG Logging Equipment Fellers/Bunchers 0.70 0

2268008005 CNG Airport Support Equipment 0.56 681

2268009010 CNG Other Underground Mining Equipment 0.80 260

2268010010 CNG Other Oil Field Equipment 0.90 1104

2282005010 2-Stroke Outboards 0.21 34.8

2282005015 2-Stroke Personal Watercraft 0.21 77.3

2282010005 4-Stroke Inboards 0.21 47.6

2282020005 Diesel Inboards 0.43 200

2282020010 Diesel Outboards 0.43 150

2282020025 Diesel Sailboat Aux. Outboard (unused) 0.43 68

2285002015 Diesel Railway Maintenance 0.21 943

2285003015 2-Stroke Gasoline Railway Maintenance 0.62 184

2285004015 4-Stroke Gasoline Railway Maintenance 0.62 184

2285006015 LPG Railway Maintenance 0.62 184

2285008015 CNG Railway Maintenance 0.62 184

* Activities for off-road motorcycles and all terrain vehicles are in units of miles per year.
30

Appendix B

Documentation of the Median Life Values in the California OFFROAD

Model
31

DOCUMENTATION OF DIESEL ENGINE LIFE

VALUES USED IN THE ARB

OFF-HIGHWAY MODEL

Prepared for:

OFFICE OF MOBILE SOURCES

ENVIRONMENTAL PROTECTION AGENCY

Ann Arbor, MI

EPA Purchase Order: 1A-0462-NASX

Prepared by:

ENERGY AND ENVIRONMENTAL ANALYSIS, INC.

1655 North Fort Myer Drive

Suite 600

Arlington, VA 22209

September 2001
32
33

TABLE OF CONTENTS

Page

1. BACKGROUND .................................................... 1

2. PSR DATA DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3. EEA ANALYSIS OF THE PSR DATA ................................... 3

4. USEFUL LIFE VALUES IN THE MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5. SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

APPENDIX A: LIST OF CONTACTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

LIST OF TABLES

Page

Table 1 PSR Data on Engine Life at Rated Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Table 2 1991 Engine Models by Horsepower Category ........................ 9

LIST OF FIGURES

Page

Figure 1 51-750 HP Diesel Engine Life Spans ............................... 7
34

(Engine Life)i = (Engine Life)full load

(Load Factor)i

1. BACKGROUND

In the 1992-1993 time frame, EEA developed a model for the California Air Resources Board

(ARB). The model estimates emission inventory from off-highway mobile sources of all types. 

The model’s emissions calculations require tracking of the population of each equipment

type/engine combination by vintage. The vintage distribution of any particular type of offhighway equipment and engine type is determined from a scrappage model that requires engine

useful life as an input. The same engine type can be utilized across a number of equipment types

that place different loads on the engine. The scrappage model is constructed in a manner that

allows useful life for a given equipment type to vary based on the simple formulation that engine

life in application “i” is given by:

Hence, engine life in a particular application is inversely proportional to the average load factor,

and engine life at full load is specified within the model.

Engines were categorized by fuel type, horsepower range and engine cycle (two- versus fourstroke). At this subcategory level, the population of engines was assumed to be homogeneous,

based on the fact that engines competing in the marketplace for the same market segment offer

competitive durability. The development of specific engine life estimates for each engine

subcategory is described in this memorandum.

It should be noted that the ARB Off-Highway Model is the first of its kind, and was developed in

a period when virtually all information had to be obtained from original sources and very few

were available publicly. Given the wide range of engines and equipment available in the offhighway market, a number of simplifying assumptions had to be made. Some of the data and

inputs in the model are potentially outdated, based on new research and testing conducted in the

last decade years following its development.

Second, it should be noted that the single most important source of data for equipment type,

population and useful life was Power Systems Research (PSR), that has a proprietary database on

off-highway equipment sales, population and scrappage. While the Power Systems Research

data was the single largest and most unified source of data, EEA conducted a detailed assessment

of PSR populations and sales data provided by comparing these data with data from other

sources. In many instances, we found PSR data could not be justified, and EEA changed the data

based on inputs from industry associations and engine manufacturers. In particular, the PSR

engine life data appeared to be most incorrect for smaller engines.
35

P opulation = ∑ S ale s

i x S urvival R ate i i

Engine Life at Rated HP (hours)

Load Factor x Use (hours/year)

Population ≅ Average Sales x engine life (years)

This memo first describes the PSR data and specifically identifies areas where our comparison

indicated that PSR was likely in potential error. Second, EEA describes the methodology by

which we derived other data that were judged more appropriate for the model.

2. PSR DATA DESCRIPTION

Data purchased from PSR included detailed breakouts of California off-highway populations by

engine type, fuel type and horsepower range. PSR also provide a separate data file on the mean

engine life by engine model in hours at rated load.

The PSR methodology for estimating population is based on sales and scrappage. PSR obtains

sales data from a number of proprietary sources including manufacturers and dealers. 

Nationwide sales are allocated to regions based on survey data and dealer based information. 

Scrappage is estimated as a function of vintage and engine mean life. Central to the estimates is

a non-dimensional survival curve that provides survival rates in percent on the Y-axis against

fraction of engine life used. The curve is S-shape, and starts at one at zero engine life used. At

engine life equal to one, the survival rate is fifty percent, and at engine life equal to two, survival

rate is zero. Hence, the engine life value is the point where half of all engine are scrapped.

Engine life in a particular application is engine life at rated load divided by the load factor on a

typical duty cycle for the application. PSR has developed load factors for each application

although we have no explicit understanding of how the load factors were developed. Engine life

at rated load is determined by a proprietary formula that related life to bore/stroke, design type

and specific output. The formula itself is proprietary and undocumented. Nevertheless, we

obtained a detailed database on life by engine model to allow us to assess the formula.

Population is derived from sales with the formula:

summed over i = 0 to twice the engine life in the application. Engine life in years for an

application is given by:

For equipment types that have no time trend in sales, we can estimate population using:
36

We utilized the above formula in several instances to estimate populations from available sales

data. In many cases, sales of off –highway equipment have shown no growth trend over a long

period, so that the above formula can provide a reasonable estimate of population.

3. EEA ANALYSIS OF THE PSR DATA

A very detailed comparison of PSR population estimates by equipment category was undertaken. 

Briefing charts presented to the ARB documenting all the comparisons have been provided to

EPA, and only the key data and major conclusions are presented here.

In lawn and garden equipment, PSR population data from most non-commercial equipment such

as chain saws and lawn mowers were a factor of ten higher than estimates from the industry or

estimates based on (sales x useful life). For commercial equipment, PSR’s estimates were more

reasonable and comparable to other estimates. However, most lawn and garden equipment are

powered by gasoline engines. For recreational equipment such as motorcycles, snowmobiles and

ATVs, PSR estimates were very low relative to other estimates. This category also has no diesel

powered equipment.

For industrial equipment, PSR totals across all fuel types and horsepower categories were

comparable to estimates from industry associations. However, the gasoline (and LPG)-to-diesel

split was very different. Diesel engine equipment populations were significantly over-estimated

by PSR (by a factor of three to four), while gasoline engine equipment populations were

underestimated significantly. Similar trends were also found for transport refrigeration units, and

diesel airport ground support equipment. These equipment typically are powered by diesel

engines in the 25 to 100 HP range.

No validation of PSR data could be done for light commercial equipment such as generator sets,

pumps and compressors. One study by Booz-Allen Hamilton suggested PSR estimates for

diesels were incorrect by more than an order of magnitude, although the Booz-Allen numbers for

diesels are not well documented. Equipment in this category utilize diesel engines under 50 HP.

PSR population data for agricultural tractors (typically in the 50 to 150 HP range) were also

significantly higher than estimates from the Agricultural Census and sales based estimates. The

differences were in the range of 50 to 150 percent.

Finally PSR estimates of populations for construction equipment were much closer to those

derived from sales or industry data on populations. These equipment typically use diesel engines

over 200 HP. PSR estimates were higher than those from industry, but the margin of difference

was not large, ranging from 10 to 30 percent.

As a result of this comparison, we concluded that PSR’s diesel engine life estimates appeared to

be optimistic, and the level of optimism increased with decreasing HP. It appeared that for small

diesel engines (less than 50 HP), the PSR life estimates were potentially in serious error. As a
37

result of the population analysis, we requested and obtained the detailed PSR life data by engine

model. Due to its proprietary nature, only aggregate statistics are provided in this report.

Table 1 provides the PSR useful life data after filtering the data for zeroes and blanks. (There

were only a very small number of such cases, including one obvious typographical error). As

shown in Table 1, the average engine life by HP range declines with increasing horsepower,

although the decline is not large relative the distribution of values within engine HP range. For

example, all engines in the 25 to 750 HP range have an average life of 10,700±1300 hours. 

Based on our knowledge of engines and their applications, the declining trend as well as the

absolute values appeared incorrect, especially for the smaller engines.

Since the variation of useful life with HP ranges were larger than the changes to the averages

across HP ranges, we use investigated the data more thoroughly. The detailed data showed that

engine life appeared to be a stronger function of its aspiration (turbocharged or naturally

aspirated) than its displacement or power output. Within naturally aspirated engines, there was a

trend to increasing average useful life with size and horsepower, ranging from 12,000 hours for

small engines to 18,000 hours for the largest engines. (A few engines had even higher useful life

numbers, but it was not clear why). However, a given engine model’s useful life was found to be

inversely proportional to its horsepower output. For example, most of the larger engines are

offered in naturally aspirated, turbocharged and aftercooled models at a variety of HP ratings. 

The PSR model simply scales the life in exact inverse proportion to the HP rating.

Figure 1 shows the distribution of useful life ratings from engines in the 50 to 750 HP range. 

Most naturally aspirated engine are in the upper end of the life range, turbocharged engines in the

middle of the range and turbocharged/aftercooled engines in the lower end of the useful life

range, in concert with their increasing specific output. Two stroke engine, with specific output

almost twice the specific output of four-stroke engines, had the lowest useful life values. The

decline in average useful life with increasing HP in Table 1 is due to the fact that a larger

proportion of high HP engines are turbocharged, or turbocharged and aftercooled, but is not

related to the larger engine size.
38

TABLE 1

PSR DATA ON ENGINE LIFE AT RATED LOAD

(hours)

HP Range Sample Size Average* Maximum Minimum Standard

Deviation

2.1 – 15 104 13,704 29,713 5,579 1,705

15.1 – 25 88 12,364 16,062 4,178 2,404

25.1 – 50 118 11,315 23,625 5,406 3,463

50.1 – 120 241 10,331 22,627 4,469 3,463

120.1 – 175 106 11,994 31,171 3,910 4,135

175.1 – 250 17 11,038 20,847 3,029 3,907

250.1 – 500 189 10,076 19,452 4,464 2,695

500.1 – 750 36 9,490 18,968 3,927 2,986

750+ 27 8,264 18,654 5,070 2,818

* Average across all engine models without sales weighting.
39

51-750 HP Diesel Engine Life Spans

0

80604020

120100

0 4000 8000 12000 16000 20000

Life (hours)

es umber of EnginN

Figure 1
40

EEA’s knowledge of engines suggested that the PSR approach was incorrect. For example,

Detroit Diesel’s two-stroke engines do not have the reputation for wearing out twice as fast as

other competitive four-stroke engines in truck applications. In addition, we are generally

unaware of any major decrease in life for turbocharged and aftercooled engines in the onhighway segment relative to turbocharged or naturally aspirated engines. Hence, EEA

decided to specify the useful life data independently of PSR data.

4. USEFUL LIFE VALUES IN THE MODEL

EEA took a three-step approach to determining the correct useful life, as follows. First, we

identified popular (high sales) engines within each horsepower category. Second, we

contacted a subset of the engine manufacturers of these popular engines to obtain their views

on engine life. Third, we developed engine life based on a combination of manufacturer

comments and available data from on-highway engines.

The identification of popular engine models by horsepower range was based on data

developed under earlier studies for ARB by EEA. Table 2 shows the data for diesel engines

above 50 HP. (The horsepower ranges in the table do not exactly correspond to those in the

model, since ARB requested some changes in the ranges towards the end of the project).

In general, the four major on-highway diesel engine manufacturers (Cummins, Caterpillar,

Detroit Diesel and IH, now Navistar) offer versions of their on-highway products for the offhighway market. In addition, John Deere is the only the other major domestic engine

manufacturer that sells engines directed almost completely to the off-highway market. 

Kubota, Deutz and Perkins are the major import engine brands in the market for engines over

50 HP.

In the 50–120 HP market, sales are dominated by four-cylinder versions of six-cylinder onhighway medium heavy-duty engines such as the Cummins B and C series, the Caterpillar

1.1L/cylinder series and the 3200 series, and Detroit Diesel’s 53 Series engines. In the next

higher range of 120 to 175 HP, on-highway medium-heavy duty engines and some naturally

aspirated versions of heavy-heavy duty engines dominate sales. Above 175 HP, a majority of

engines are derivatives of heavy-heavy duty on-highway engines, except at the highest

horsepower end, over 500 HP. At these high HP levels, some specialized engines such as

Caterpillar’s 3500 series, DDC’s 149 series and Cummins KT series are available and are not

generally sold in the on-highway market. Sales of engines in the very high HP categories are

quite small.

In the lower horsepower ranges below 50 HP, two types of engines dominate sales. In

industrial tractors and small airport ground support equipment, derated versions of passenger

car diesel engines (from manufacturers like Perkins, VW, Isuzu and Toyota) are utilized.

Such engines are typically rated from 30 to 50 HP. 
41

TABLE 2

1991 ENGINE MODELS BY HORSEPOWER CATEGORY

Manufacturer 50 to120 HP 120 to 250 HP 250 to 500 HP Over 500 HP

Caterpillar 3114T

3204NA

3304NA

3116T

3208NA

3306NA

3306T/TA

3406T/TA

3408T/TA

3412T/TA

3408TA

All 3500 series

Cummins 4A2.3

6A3.4

4B3.9

6B5.9T/TA

6C8.3T/TA

L-10T/TA

NTC-855T/TA

KT-19

VT-28

KV-38

Detroit Diesel 3-53N/T

4-53N

8.2L N

3-53T

4-53T

6-71N

6-71T/TA

8-71T/TA

6-92N/T/TA

8-92T/TA

12-92T/TA

All 149 series

Deere 3-179N/T

4-239N/T

4-276N/T

6-359T/TA

6-414T/TA

6-466T/TA

6-619T/TA

8-955T/TA

IH D-239N/T

D-360N

D-360T

D-466N/T/TA

Komatsu 4D-94N/T

4D-95N/T

4D-105N

4D-130N/T

6D-95N/T

6D-105N/T

6D-125T/TA

6D-140N/T

6D-155N/T

6D-170T/TA

8V-170T/TA

12V170T/TA

Deutz FL912N/T

FL913N/T

FL913T/TA

FL413N/T

FL413T/TA

FL513T/TA

Perkins 3-153N/T

4-236N/T

6-354N/T

8-540N/T

6-734T/TA

8-1062T/TA

N is for naturally aspirated, T for turbocharged and A for aftercooled.
3

* contact names are listed in Appendix A.

42

Small two- or three-cylinder engines from manufacturers such as Kubota, Yanmar, Onan, and

Teledyne-Wisconsin are utilized in the 15–40 HP range and are a mix of air cooled and

water-cooled engines. Engines under 15 HP are also offered by these same manufacturers

and are mostly single-cylinder air-cooled diesels. Most of these engines find application is

light commercial equipment.

Useful life estimates for engines over 50 HP were based on information from heavy-duty

diesel engine manufacturers. EEA spoke with representatives from Caterpillar, Cummins,

Navistar and Detroit-Diesel.3

 All were questions about the:

· correctness of the PSR algorithm of scaling life by load factor, and by specific output;

· typical useful life in on-highway applications;

· comparability to useful life in off-highway applications.

Information obtained was subjective and experienced based, but no hard data was provided

by manufacturers.

On PSR’s useful life algorithms, manufacturers agreed that load factor was inversely related

to engine life but cautioned that this relationship could not hold over the entire range of load

factors from zero to one. They believed it would overestimate life at very light load factors

and underestimate life as load factor approached one. They did not agree, however, with

PSR’s method of derating life at full load inversely with specific output across all aspiration

types. While suggesting that there is variation in life with increasing output, manufacturers

also stated that many components are upgraded in turbocharged engines relative to their

naturally aspirated counterparts, and that warranty protection is the same for all engine types. 

They also pointed to the evidence that inspite of increasing specific output in the late-1980s

and early 1990s, they had not observed any significant change in useful life.

For heavy-heavy duty on-road engines, most manufacturers agreed that engine life (defined as

the point when the engine is removed from the truck for a rebuild) for an over-the-road

application, i.e., mostly highway miles, was in the 700,000 to 750,000 miles range. Note that

this referred to engines from the last decade, as we understand that current engines last up to

a million miles. Manufacturers suggested that miles could be converted to hours by assuming

that most mileage was accumulated at highway speeds of, say, 60 mph as an average. 

Manufacturers also generally agreed that EPA’s original durability finding that mediumheavy duty engines have two-thirds the life of heavy-heavy duty engines was a reasonable

estimate.

In order to develop useful life at rated HP, a load factor corresponding to 60 MPH operation

is required. Simulation models such as “TCAPE” show that an 80,000 lb. GVW truck

cruising on a level road at 60 mph requires 210 to 220 HP. A typical engine rated HP for the

application is 350 HP to 375 HP, suggesting a load factor of 0.6. It is also known that trucks
43

Life = 700,000 miles

60 mph

x Load Factor

= 7000 hours

are geared to operate at close to the best bsfc point at cruising speed. The best bsfc point

usually occurs at 70 percent of peak torque and close to the peak torque RPM which is about

70 percent of rated RPM. Peak torque is usually about 20 percent higher than trque at rated

RPM. Since:

Rated HP = (Torque)R x (RPM)R

where subscript R is for rated values, we can calculate

Peak Torque @ 1.2 x (Torque)R

RPM @ Peak Torque = 0.7 x (RPM)R

Cruise Point 0 0.7 x Peak Torque x RPM @ Peak Torque

= 0.7 x 1.2 x (Torque)R x 0.7 x (RPM)R

@ 0.6 x (Torque)R x (RPM)R

Hence, the cruise point calculation also implies a load factor of about 0.6. 

From this, we can derive a life at rated power in hours:

Manufacturers had only subjective opinions for the life in off-road use, and suggested some

adjustment factor for “rough-duty” conditions. These suggestions were to reduce the onhighway life by 10 to 20 percent, and we selected 15 percent as an approximate average. 

Adjusting the on-highway life of 7000 hours by 15 percent provided a useful life rating for

off-highway engines of 6000 hours. Using the fact that medium duty engines offered twothirds the life of heavy-heavy duty engines, we estimated their life at 4000 hours.

Useful life for smaller engines (under 50 HP) was based on less information. EEA contacted

representatives from Kubota, Yanmar, Perkins and VW to obtain information on diesel

engine useful life but they had no specific information on hours. One manufacturer

suggested using information on forklift truck scrappage, but we found that the Industrial

Truck Association only has an average life for all fork-lifts (gasoline and diesel), and the data

was not directly useful. Several members commented that the engines were physically

similar in design to light-duty automotive diesels, which was the basis for our estimate of

life. Because of the very low load factor (around 0.1) in typical automotive use, a mileage

based estimate leads to very long useful life (>10,000 hours). Rather, we utilized the fact that

small light duty (passenger car) diesel have durability comparable to gasoline engines of

similar displacement. Data from auto-manufacturers show that a typical wide open throttle

durability requirement for gasoline four-cylinder engines is about 2500 hours. This value

was used for diesel engines in the 15 to 50 HP range. No adjustments were made for offhighway use, since these engines are typically not used in rough duty applications.
44

Diesels in the under 15 HP category are typically small single cylinder air-cooled engines. 

Again, no specific life figures were obtained from manufacturers. However, they believed

that durability was lower than the value of the larger water cooled multi-cylinder units in the

15-50 HP category. EEA selected 1250 hours as a plausible value, but recognize that this is

not supported by any data. It also reflects the fact that it is about ten percent of PSR’s

estimate. Given that PSR estimates of small diesel populations are over ten times the

estimates of other organizations, the value appears to be a reasonable estimate.

5. SUMMARY

Based on detailed comparison of populations, it appeared that PSR overestimates diesel

equipment populations, with the level of overestimate increasing from the 20 percent range

for the largest diesels to over 1000 percent for the smallest diesels.

A detailed examination of their data on engine useful life at rated load showed

counterintuitive estimates, with the smallest diesel engine having substantially higher useful

life relative to the largest diesels. These estimate were traced to assumptions about the

relationship of engine life to specific output (HP/liter) that EEA believes are incorrect.

EEA developed its own estimates by comparison with on-road engines useful life, where

engine types in each HP range were matched with on-road counterparts. Data for engines

under 50 HP, however, was unavailable and based largely on subjective comments from the

manufacturers. The ratio of EEA useful life estimates to PSR estimates for each HP category

is quite similar to the ratio of equipment population estimates from other sources to PSR’s

equipment population estimates, suggesting that EEA useful life estimates are reasonable.
45

APPENDIX A

LIST OF CONTACTS

Caterpillar Don Dowdall

Cummins Mike Brand

Navistar (IH) Ed Sienecke

Detroit Diesel John Fisher

Kubota Kevin Kokrda

Yanmar Norman Weir and Kozuhiro Nomura

Perkins P.A. Harrison (England)

VW Wolfgang Groth