ŁEPA
        Air and Radiation                   EPA420-P-04-015
                                April 2004
                                NR-015a
United States    	
Environmental Protection
Agency
        Weekday and Weekend Day
        Temporal Allocation of
        Activity in the Draft
        NONROAD2004 Model

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                                                        EPA420-P-04-015
                                                       Revised April 2004
 Weekday and Weekend Day Temporal Allocation of
       Activity in the Draft NONROAD2004 Model
                             NR-015a
                     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.

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          Weekday and Weekend Day Temporal Allocation of Activity
                       In The Draft NONROAD2004 Model

                                Report No. NR-015a
                                  Revised April 2004

                           Assessment and Standards Division
                      EPA, Office of Transportation and Air Quality

1. Introduction

   The EPA is developing a national nonroad air emissions inventory model called NONROAD.
The latest version of this model is draft NONROAD2004. The model uses estimates of annual
activity for each equipment type, generally expressed in terms of hours of operation or gallons of
fuel used per year, to calculate yearly emission inventories. It will also calculate inventories on a
seasonal (i.e., summer, fall, winter, spring), monthly, or daily (i.e., weekday or weekend day)
basis by allocating annual activity to these smaller time periods. This memorandum documents
the daily activity allocation fractions used in the current, draft version of NONROAD. The
fractions are expressed as weekday and weekend day fractions of weekly activity and are
provided for each equipment/category type. Seasonal and monthly activity allocation fractions
are addressed in a separate technical memorandum (Report No. NR-004b).

   Section 2 provides a background and description of the basic sources of information used.
Section 3 defines the fractions and how they are used in the model. Section 4 provides a list of
the default fractions used in the model.

2. Background and Data Sources Used

   The weekly temporal activity allocation feature of draft NONROAD2004 allows the user to
distribute nonroad equipment activity between weekdays and weekend days. This feature
coincides with NONROAD's ability to allocate equipment activity to a specific month and
season, thereby allowing the user to model a typical weekday or weekend day during a given
month and season (e.g., a typical summer weekend day in June). State and local air agencies may
want or need the ability to model weekly activity in order to analyze the effects of episodic
controls or voluntary incentive programs involving specific categories or types of nonroad
equipment.

   At the weekly level, temporal activity allocation is largely dependent on people's
recreational and work patterns as well as the purpose for which the equipment is used. For
example, most commercial lawn and garden equipment activity occurs on weekdays when lawn
care services tend to operate. In contrast, recreational marine equipment is used primarily  on
weekends.

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   The Nonroad Engine and Vehicle Emission Study (NEVES)1 did not include a study of
weekly activity patterns. Its main purpose was to assess the annual and seasonal contribution of
nonroad equipment emissions to the total air pollution inventory for all sources, so it did not
require that level of detail.

   For the draft version of NONROAD2004, the fractions for residential lawn and garden
equipment, commercial lawn and garden equipment, and recreational marine equipment are
based on available survey data. For the remaining equipment types for which survey data are not
available, fractions are based on EPA's assessment of typical usage patterns and,  for similar
equipment types, comparison with the off-highway model (OFFROAD, formerly  known as
MVOFF) developed by the California Air Resources Board.2 The draft version of
NONROAD2004 and OFFROAD have similar weekday and weekend day activity fractions for
common equipment types.

3. Methodology

   The draft version of the NONROAD2004 model has the capability to accept two fractions
that represent the amount of activity allocated to  each weekday and each weekend day. These
fractions are contained in the seasonal/monthly allocation file (season.dat) following the
seasonal/monthly allocation fractions. The weekday fraction represents equipment activity
during each of the five weekdays and the weekend day fraction represents the activity during
each of the two weekend days. For example, survey data indicate that 80 percent of commercial
lawn and garden activity occurs Monday through Friday and 20 percent occurs during Saturday
and Sunday. The resulting weekday and weekend day fractions are:

          Weekday Fraction = 0.80/5 = 0.16, or 16% per weekday
          Weekend Day Fraction = 0.20/2 = 0.10, or 10% per weekend day

Through the use of Source Category Codes (SCCs), weekday and weekend day fractions are
assigned for each equipment category (e.g., construction equipment). All equipment types within
a category (e.g., excavators within the construction equipment category) are assigned the
weekday and weekend day fractions for that category. Users may substitute local  activity data
where  available.

4. Default Weekday and Weekend Day Activity Allocation Fractions Used in Draft
   NONROAD2004

   The default weekly activity allocation fractions contained in the draft version  of NONROAD
are shown in Table 1.
          Environmental Protection Agency, Office of Air and Radiation. Nonroad Engine and Vehicle
          Emission Study. 21A-2001, November 1991.

          Energy and Environmental Analysis. Documentation of Input Factors for the New Off-Road Mobile
          Source Emissions Inventory Model - Draft. Prepared for the California Air Resources Board, August
          1995. OFFROAD was formerly known as MVOFF.

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                                          Table 1
            Default Weekday and Weekend Day Activity Allocation Fractions
                              Used in Draft NONROAD2004*
Equipment Category
Recreational
Construction
Industrial
Residential Lawn and Garden
Commercial Lawn and Garden
Agricultural
Light Commercial
Logging
Airport Service
Railway Maintenance
Recreational Marine
Transportation A/C Refrigeration
Underground Mining
Oil Field Equipment
Weekday
0.1111111
0.1666667
0.1666667
0.1111111
0.1600000
0.1666667
0.1666667
0.1666667
0.1428571
0.1800000
0.0600000
0.1428571
0.1666667
0.1428571
Weekend Day
0.2222222
0.0833334
0.0833334
0.2222222
0.1000000
0.0833334
0.0833334
0.0833334
0.1428571
0.0500000
0.3500000
0.1428571
0.0833334
0.1428571
* The values are the fractions of weekly activity allocated to each weekday and each weekend day. To get the
fraction for all weekdays, multiply the weekday fraction by 5. Similarly, to get the weekend fraction, multiply the
weekend day fraction by 2. All equipment types within a category (e.g., excavators within the construction
equipment category) are assigned the weekday and weekend day fractions for that category.
    As seen in Table 1, recreational equipment is assigned a pattern of twice as much use on the
weekend days compared to the weekdays, based on an assessment of typical usage patterns. The
fractions for recreational equipment are also in agreement with those used in California ARB's
OFFROAD model (hereafter, simply referred to as OFFROAD).

    The construction, industrial, agricultural, light commercial, logging, and underground mining
categories are commercial in nature, and should be used more on weekdays than on weekend
days; therefore, it is estimated that these equipment categories are used twice as much on the
weekdays compared to the weekend days. For the construction, industrial, agricultural, light
commercial, and logging categories, this estimate is very similar to the weekday/weekend day

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activity fractions (0.164 weekday, 0.090 weekend day) specified in OFFROAD.3
Weekday/weekend day activity fractions for the underground mining category are not specified
in OFFROAD.

   Airport service equipment, transportation A/C refrigeration equipment, and oil field
equipment were thought to be used uniformly throughout the week. For the airport service
equipment and transportation A/C refrigeration categories, this agrees with the estimates in
OFFROAD. Weekday/weekend day activity fractions for the oil field equipment category are not
specified in OFFROAD.

   In contrast to the above equipment categories, survey data are available for the residential
lawn and garden, commercial lawn and garden, and recreational marine categories. The surveys
are described below, followed by a discussion of how they were used to develop weekday and
weekend day activity fractions for these three categories.

   Systems Applications International, Inc. (SAI) conducted a survey of recreational marine use
in California for the California Air Resources Board.4 The survey was part of a larger effort to
develop an emissions inventory of pleasure craft in California. From June 1993 to May  1994,
over 10,000 surveys were sent to randomly selected owners of motorized pleasure craft
registered with the California Department of Motor Vehicles. Temporal (seasonal, weekly,  and
diurnal) profiles were obtained with the  survey data. Profiles are provided of the percent of
weekly activity for each day of the week, on both an annual basis and for the winter season. In
both cases, usage during the week is fairly flat (less than or equal to 10% each weekday), with
60-70% of the total weekly activity occurring on the weekend. On an annual basis, the daily
activity fractions are as follows: Monday (0.0527578), Tuesday (0.0621816), Wednesday
(0.0702681), Thursday (0.0723208), Friday (0.1043395), Saturday (0.3039638), and Sunday
(0.3341683). When combined, the fraction  of activity on all weekdays is 0.36 and the fraction of
activity on the weekend is 0.64.

   SAI also conducted a telephone survey  of weekly activity patterns for residential and
commercial lawnmowers in the Houston/Galveston and Beaumont/Port Arthur areas for the
Texas Natural Resources Conservation Commission (TNRCC).5 Again, this was part of a larger
effort to develop an emissions inventory for selected area and nonroad sources. Profiles are
provided of the percent of weekly activity for each day of the week for both residential and
       3  OFFROAD has separate activity fractions for each day of the week. In order to compare the estimates
          with NONROAD, the fractions for each weekday were summed and divided by five to obtain the
          weekday fraction. The fractions for Saturday and Sunday were summed and divided by two to obtain
          the comparable weekend day fraction.

       4  Systems Applications International. Development of an Improved Inventory of Emissions from
          Pleasure Craft in California. Contract Number A132-184, Prepared for the California Air Resources
          Board, June 1995.

       5  Systems Applications International. Bottom-Up Emission Inventory Development for Selected Source
          Categories in the Houston-Galveston and Beaumont-Port Arthur Areas. Prepared for the Texas Natural
          Resource Conservation Commission, May 1995.

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commercial lawnmowers. For residential lawnmowers, the daily activity fractions are as follows:
Monday (0.11), Tuesday (0.10), Wednesday (0.11), Thursday (0.15), Friday (0.16), Saturday
(0.24), and Sunday (0.14). When combined, the fraction of activity on all weekdays is 0.63 and
the fraction of activity on the weekend is 0.38. For commercial lawnmowers, the daily activity
fractions given in the SAI report are 0.16 for each weekday and 0.10 for each weekend day. This
translates into a combined weekday fraction of 0.80 and a combined weekend fraction of 0.20.

   There are also estimates of weekday vs. weekend use for residential lawnmowers and
recreational marine equipment provided by the Texas Air Control Board.6 During the first week
in August  1993, the North Central Texas Council of Governments (NCTCOG) conducted an in-
house survey to measure the level of consumer lawn mower usage and the degree of weekend
usage in the Dallas-Fort Worth area. The results indicated a mean combined weekday activity
fraction of 0.504 and a combined weekend fraction of 0.496. Based upon NCTCOG survey data
of area lake authorities, the combined weekday and weekend fractions of summer boating
activity are 0.25 and 0.75, respectively.

   For residential lawn and garden equipment, the SAI and NCTCOG survey results were
averaged to obtain a combined weekday fraction of 0.56 and a combined weekend fraction of
0.44. This translates into daily activity fractions of 0.11 for weekdays and 0.22 for weekend
days.

   For commercial lawn and garden equipment, the single source of survey data is the SAI
telephone survey in the Houston/Galveston and Beaumont/Port Arthur areas.  The daily activity
fractions given in the SAI report (0.16 for each weekday and 0.10 for each weekend day) are
used directly in NONROAD.

   For the commercial marine category, SAFs annual estimates of pleasure craft activity  in
California were averaged with NCTCOG's estimates of summer recreational boating activity in
the Dallas-Fort Worth area to obtain a combined weekday fraction of 0.30 and a combined
weekend fraction of 0.70. This translates into daily activity fractions of 0.06 for weekdays and
0.35 for weekend days.

   The EPA welcomes suggestions and comments about the approach and sources of
information used, as well as information about other surveys of nonroad equipment that have
been or are presently being conducted.
          Memorandum from Everett Bacon and Michael Burbank, North Central Texas Council of Governments
          to Bill Gill, Texas Air Control Board. Recreational Boating and Lawn and Garden Off-road Emission
          Inventories for the Dallas-Fort Worth Nonattainment Area. August 13, 1993.

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