\364\ Roeth, Mike, et al. ``Barriers to Increased Adoption of
Fuel Efficiency Technologies in Freight Trucking,'' July 2013.
International Council for Clean Transportation. Available here:
http://www.theicct.org/sites/default/files/publications/ICCT-NACFE-CSS_Barriers_Report_Final_20130722.pdf.
    \365\ See RIA Chapter 7.2.5 and Memo to Docket ``Tractor-Trailer
Cost per Ton Values.'' July 2016. EPA-HQ-OAR-2014-0827.
---------------------------------------------------------------------------

    The agencies believe these technologies can be adopted at the
projected rates within the lead time provided in the trailer program,
as discussed above in Section IV.C.(4) above.
(4) Alternative Standards and Feasibility That the Agencies Considered
    As discussed in Section X of the NPRM, the agencies evaluated five
regulatory alternatives representing different levels of stringency for
the Phase 2 program. See 80 FR 40273. A wide range of stakeholders
commented on the proposed (Alternative 3) standards and the other
alternatives that we discussed, and our final standards reflect our
consideration of all of those comments.
    Comments on our proposed standards (Alternative 3) and the
alternatives we presented generally fell into three categories: (1)
Commenters supporting Alternative 1; i.e., generally advocating no
mandatory standards and a continuation of today's voluntary SmartWay
regime and; (2) Commenters preferring the proposed Alternative 3
standards and timeline to the standards of Alternative 4; and (3)
Commenters supporting the more stringent standards and timeline of
Alternative 4, Alternative 5, or of other more stringent potential
programs.
    Commenters including the TTMA, Utility, and Stoughton stated their
belief that no mandatory standards are necessary; however, they did not
provide information to show that market forces at work today will
achieve the clear potential for the industry to reduce CO2
and fuel consumption in the near- and longer-term future. The agencies
have concluded that a program involving no or minimal mandatory
requirements would not be appropriate or meet our statutory
requirements.
    As discussed previously, the agencies believe that our final
trailer standards are appropriate under the Clean Air Act and are the
maximum feasible standards under the EISA. In developing the proposal
and the final rule, we considered standards that would be more
stringent or would become effective in an earlier model year than the
proposed Alternative 3 standards and timeline. Several commenters
stated that a still more stringent program should be finalized,
including information about current and potential future trailer
aerodynamic technologies. Commenters including CARB, NACAA, NRDC, ICCT,
UCS, and STEMCO supported the standards we presented for Alternative 4
in the proposal (essentially the pull ahead of the MY 2027 standards)
in the proposal. In addition, some of the commenters made the
additional suggestion that the agencies should anticipate that
manufacturers will incorporate a modest degree of Bin VIII
technologies--i.e., two bins higher than any performance demonstrated
in our aerodynamic testing--in the later stages of the program. EDF
supported a program of even greater stringency, supporting Alternative
5 standards (advanced aerodynamic technologies on all box vans,
aerodynamic technologies on some non-box trailers, and tire
technologies on all non-box trailers) on the Alternative 4 timeline.
The Center for Biological Diversity (CBD) did not specifically comment
on the alternatives presented in the proposal, but supported a program
that would result in significantly more stringent standards (based, for
example, on integrated tractor and trailer technologies, such as in the
SuperTruck demonstration program). Great Dane, Wabash, ATA, and the
International Foodservice Distributors Association expressed concerns
that a program of the stringency and timeline of Alternative 4 would
have negative consequences, including requiring trailer manufacturers
to adopt less-tested technology.
    Where commenters provided relevant data and information, the
agencies made adjustments to the final program accordingly. For
example, as noted in Section IV.C.(1) and Section IV.D.(2) previously,
information from the industry was helpful in the decision to limit the
non-box trailer program to tanks, flatbeds, and container chassis.
Also, partially in response to information we received in comments, we
slightly reduced the proposed stringency for partial-aero vans to
better reflect their aerodynamic limitations. Also, while not a direct
change to the stringency of the standards, the program limits averaging
to the final stage of the program to allow van manufacturers more time
to become familiar with the compliance processes and the industry to
gain confidence in the technologies. Overall, the final standards are
slightly more stringent than proposed, based on

an expectation of earlier adoption of more efficient lower rolling
resistance tires for all subcategories, and a strengthened the full-
aero van program that includes greater adoption of advanced
aerodynamics in the final stage.
    Based on this analysis and as informed by the comments, we believe
that the final standards in the program, slightly revised from the
proposed Alternative 3 standards, are appropriate and represent the
maximum feasible standards. In contrast, we believe that the
accelerated timeline of Alternative 4 may cause technologies to
prematurely enter the market, leading to unnecessary costs and
compliance burdens that would not be appropriate for this newly
regulated industry. Standards similar to or more stringent than those
we evaluated for Alternative 5 would require CO2 and fuel
consumption reductions that may well not be technologically achievable,
even with fundamental changes to the industry. Nor did the commenters
present any information as to how advanced aerodynamic technologies
(Bins VII and VIII) could be developed and reliably brought to market
at reasonable cost within the lead time of the Phase 2 program. On the
basis of what we know today, the agencies are unable to show a pathway
for the industry to achieve such additional improvements, at least
without the potential for major disruptions to the industry due to
requiring, for example, fundamental changes to trailer design and
construction, or impractical levels of tractor-trailer integration.
E. Trailer Standards: Compliance and Flexibilities
    As with other EPA motor vehicle programs, trailer manufacturers
must annually obtain a certificate of conformity from EPA before
introducing into commerce new trailers subject to the new trailer
CO2 and fuel consumption standards. See CAA section 206(a).
The EPA certification provisions align with provisions that apply to
the NHTSA trailer program such that this single certification program
meets the requirements of both agencies.
    The certification process for trailer manufacturers is very similar
in its basic structure to the process for the other Phase 2 vehicle
programs, although it has been simplified for trailers. This structure
involves pre-certification activities, the certification application
and its approval, and end-of-year reporting.
    In this section, the agencies first describe the general
certification process and how we developed compliance equations based
on the GEM vehicle simulation tool, followed by a discussion of the
specified test procedures for measuring the performance of tires and
aerodynamic technologies and how manufacturers will apply test results
toward compliance and certification. The section closes with
discussions of several other certification and compliance provisions as
well as provisions to provide manufacturers with compliance
flexibility.
(1) General Certification Process
    Under the process for certification, manufacturers of all covered
trailers are required to apply to EPA for certification.\366\ In
addition, manufacturers of box vans subject to the performance-based
standards are required to provide aerodynamic performance test data
(see 40 CFR 1037.205) in their applications. EPA expects to provide
additional guidance to the regulated industry as the program begins to
be implemented, including an overview of the regulations, how to
prepare for compliance, and instructions for registering with the EPA.
Once a trailer manufacturer is registered with EPA, EPA's Compliance
Division in the Office of Transportation and Air Quality will assign a
staff certification representative to the company to help them through
the compliance process. After this point, manufacturers can arrange to
meet with the agencies to discuss compliance plans and obtain any
preliminary approvals (e.g., appropriate test methods) before applying
for certification.
---------------------------------------------------------------------------

    \366\ As with the other Phase 2 vehicle programs, manufacturers
submit their applications to EPA, which then shares them with NHTSA.
Obtaining an approved certificate of conformity from EPA is the
first step in complying with the NHTSA program.
---------------------------------------------------------------------------

    Trailer manufacturers submit their applications through the EPA
``Verify'' electronic database, and EPA issues certificates based on
the information provided. At the end of the model year, trailer
manufacturers submit an end-of-year report to the agencies to complete
their annual obligations.
(a) Definition of Model Year
    As mentioned previously, consistent with Clean Air Act
specifications, EPA's vehicle certification is an annual process. EPA
CO2 emissions standards start to apply for trailers built on
or after January 1, 2018, with later standards being introduced by
model year. Under the Clean Air Act, the term ``model year'' refers to
a manufacturer's annual production period. Manufacturers may use the
calendar year as the model year, or may choose a different period of
production that includes January 1 of that year. Thus, manufacturers
have the option to choose any year-long period of production that
begins on or before January 1 of the named model year, but no sooner
than January 2 of the previous calendar year. For example, at
certification, a manufacturer could specify the 2021 model year
production period to be July 1, 2020 through June 30, 2021.
(b) Preliminary Considerations for Compliance
    Before submitting an application for a certificate, a manufacturer
chooses the technologies they plan to offer their customers, and
identifies any trailers in their production line that qualify for
exclusion from the program.\367\ Non-box trailers, which are subject to
design standards, the manufacturer will need to select which tires and
tire pressure systems to include and confirm that their tires meet the
LRR performance standards. For box vans subject to performance
standards, manufacturers also obtain performance information for these
technologies at this time, either from supplier data or their own
testing. Manufacturers that choose to perform aerodynamic or tire
testing themselves may also need to obtain approval of test methods and
perform preliminary testing. Trailer manufacturers relying on data from
a third-party aerodynamic device manufacturer would need to verify that
these data are approved.
---------------------------------------------------------------------------

    \367\ Trailers that meet the qualifications for exclusion do not
require a certificate of conformity and manufacturers do not have to
submit an application to EPA for these trailers.
---------------------------------------------------------------------------

    During this time, the manufacturers also decide the strategy they
intend to use for compliance by identifying ``families'' for the
trailers they produce. A family is a grouping of similar products that
are all subject to the same standard and covered by a single
certificate. All products in each trailer subcategory are generally
certified as the same family. That is, long box dry vans, short box dry
vans, long refrigerated vans, short refrigerated vans, non-box
trailers, partial-aero vans (long and short box, dry and refrigerated
vans), and non-aero box vans, are each certified as separate trailer
families. Manufacturers may combine dissimilar trailers into a single
vehicle family to reduce the compliance burden as described in 40 CFR
1037.230(d)(3) and 49 CFR 535.5(e). In general, manufacturers can
combine trailers that have less stringent standards with more stringent
standards as long as the combined set of trailers

meet the more stringent standards. Refrigerated and dry vans of the
same length can be combined to meet the dry van standards. Short vans
can combine with long vans, meeting the corresponding long van
standard. Additionally, non-box trailers can be combined with the non-
aero box vans if the manufacturer would like to meet the more stringent
non-aero box van design standards with higher-performing tires.
    When no averaging is available (i.e., MY 2018 through MY 2026 for
full-aero box vans, and all years for remaining trailers), all products
within a family need to meet or exceed the standards for that trailer
subcategory (except for any trailers included in the manufacturer's
allowance for non-complying vehicles (See Section IV.E.(5)(a) below)).
This is not to say that, for example, every long box dry van model
needs to have identical technologies like skirts, tires, and tire
inflation systems, but that every model in that family need to meet the
standard for that family.
    In MY 2027 and later, full-aero box van manufacturers will still
generally have one family per subcategory. However, if a full-aero box
van manufacturer subject to performance standards wishes to utilize the
averaging provisions, it would need to divide the trailer models in
each of the van subcategories/families into subfamilies.\368\ Each
subfamily can be a grouping of box vans that have similar performance
levels, even if they use different technologies. We refer to the
performance levels for each subfamily as ``Family Emission Limits''
(FELs). A long box dry van manufacturer could choose, for example, to
create two subfamilies in its long box dry van family. Trailers in one
of these subfamilies could be allowed to under-comply with the standard
(e.g., not apply a tire pressure system) as long as the performance of
the other subfamily over-complies with the standard (e.g., installs
additional aerodynamic technologies), such that the average of all of
the subfamilies' FELs met or exceeded the standard for that family on a
production-weighted basis. Section IV.E.(5)(b) below further discusses
how the averaging program would function for any such trailer
subfamilies.
---------------------------------------------------------------------------

    \368\ The program essentially requires that manufacturers equip
100 percent of their non-box and special purpose box trailers with
tire pressure systems and tires meeting the specified rolling
resistance levels. Partial-aero box vans meet a reduced performance
standard. As a result, averaging provisions do not apply to these
trailer subcategories.
---------------------------------------------------------------------------

(c) Submitting a Certification Application and Request for a
Certificate to EPA
    Once the preliminary steps are completed, the manufacturer can
prepare and submit applications to EPA for certificate of conformity
for each of its trailer families. The contents of the application are
specified in 40 CFR 1037.205, though not all items listed in the
regulation are applicable to each trailer manufacturer.
    For the early years of the program (i.e., MY 2018 through MY 2020),
the application must specify whether the trailer manufacturer is opting
into the NHTSA voluntary program to ensure the information is
transferred between the agencies. Throughout the program, the
application must include a description of the emission and fuel
consumption reduction technologies that a manufacturer intends to
offer. These technologies could include aerodynamic features, LRR tire
models, tire pressure systems, or components that qualify for weight
reduction. Basic information about labeling, warranty, and recommended
maintenance should also be included the application (see Section
IV.E.(4) for more information on these additional compliance
provisions).
    The manufacturer also provides a summary of the plans to comply
with the standard. This information includes a description of the
trailer family and subfamilies (if applicable) covered by the
certificate, the technologies that are used for compliance, and
projected sales of its products. For trailers subject to performance-
based standards (and not those subject to the design-based standards),
in the earlier stages of the program when averaging is not available
(or for manufacturers of full-aero vans that do not participate in
averaging after MY 2026), additional provisions apply. These
manufacturers will include information on the configuration with the
worst performance level in terms of CO2 and fuel consumption
offered in the trailer family. Any of these manufacturers that choose
to average within their full-aero van families after MY 2026 will
include performance information for the projected highest production
trailer configuration, as well as the lowest and the highest performing
configurations within those families. For all covered trailers, once
the certification application is accepted, a certificate is issued and
manufacturers can begin selling their trailers.
(d) End-of-Year Obligations
    After the end of each year, all manufacturers, including those with
design-based standards, need to submit a report to the agencies
presenting production-related data for that year (see 40 CFR 1037.250
and 49 CFR 535.8). In addition, the year's final compliance data (as
calculated using the compliance equation) for box van manufacturers
subject to performance-based standards will include both CO2
emissions and fuel consumption information and actual production
volumes in order to demonstrate that the trailers met the standards for
that year.
    In MY 2027 and later, full-aero box van manufacturers that opt to
participate in the averaging program will submit a second report that
describes their subfamily FELs and a final calculation of their
production-weighted average CO2 and fuel consumption. See 40
CFR 1037.730, 40 CFR 1037.745, and 49 CFR 535.7. All certifying
manufacturers need to maintain records of all the data and information
that is required to be supplied to EPA and NHTSA for eight years.
(2) Evaluating Trailer Performance for Compliance
    The agencies believe that this final compliance program for trailer
manufacturers is straightforward, technically robust, transparent, and
minimizes administrative burdens on the industry. As described earlier
in this section and in Chapter 4 of the RIA, GEM is a customized
vehicle simulation model that EPA developed for the Phase 1 program to
relate measured aerodynamic and tire performance values, as well as
other parameters, to CO2 and fuel consumption without
performing full-vehicle testing. As with the Phase 1 and Phase 2
tractor and vocational vehicle programs, the trailer program uses GEM
in evaluating emissions and fuel consumption in developing the trailer
standards. However, unlike the tractor and vocational vehicle programs,
trailer manufacturers will not use GEM directly to demonstrate
compliance with the trailer standards. Instead, we have developed an
equation based on GEM that calculates CO2 and fuel
consumption from performance inputs without running the model.
(a) Development of the GEM-Based Trailer Compliance Equation
    For compliance with the performance-based standards in the trailer
program (i.e. the standards for full- and partial-aero long and short
box vans), the trailer characteristics that a manufacturer supplies to
the equation are aerodynamic improvements (i.e., the change in the
aerodynamic drag area,

delta CdA, from the appropriate bin in m\2\), tire rolling
resistance (i.e., coefficient of rolling resistance, CRR, in
kg/metric ton), the presence of a tire pressure system, and any weight
reduction applied in pounds. The use of the equation quantifies the
overall performance of the trailer in terms of CO2 emissions
on a grams per ton-mile basis, which can be converted to fuel
consumption on a gallons per 1000 ton-mile basis.
    Chapter 2.10.5 of the RIA provides a full a description of the
development and evaluation of the equation for trailer compliance where
the standards are performance-based. Equation IV-1 is a single linear
regression curve that can be used for all box vans in these rules to
calculate CO2 emissions, eCO2. Unique constant
values, C1 through C4, are applied for each of
the van types as shown in Table IV-24. Constant C5 is equal
to 0.988 for any trailer that installs an ATIS (accounting for the 1.2
percent reduction given for use of ATI), 0.990 for any trailer that
installs a TPMS, or 1.0 for trailers without tire pressure systems. We
found that this equation accurately reproduces the results of GEM for
each of the box van subcategories, and the program requires these
trailer manufacturers use Equation IV-1 to calculate CO2 for
compliance. Manufacturers insert their tire rolling resistance level
(TRRL), wind-averaged change in drag area ([Delta]CdA),
weight reduction value (WR) (if applicable), and the appropriate
C5 value if a tire pressure system is installed into the
equation and submit the result to EPA. The program provides for
manufacturers to use a conversion of 10.180 grams of CO2 per
gallon of diesel to calculate the corresponding fuel consumption values
for compliance with NHTSA's regulations. See 40 CFR 1037.515 and 49 CFR
535.6.
[GRAPHIC] [TIFF OMITTED] TR25OC16.009

                                            Table IV-24--Constants for GEM-Based Trailer Compliance Equation
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                C[ihel5] (tire pressure)
             Trailer  subcategory                  C[ihel1]        C[ihel2]        C[ihel3]        C[ihel4]    -----------------------------------------
                                                                                None          TPMS          ATIS
--------------------------------------------------------------------------------------------------------------------------------------------------------
Long Dry Van..................................            76.1            1.67           -5.82        -0.00103        1.000         0.990         0.988
Long Refrigerated Van.........................            77.4            1.75           -5.78        -0.00103
Short Dry Van.................................           117.8            1.78           -9.48        -0.00258
Short Refrigerated Van........................           121.1            1.88           -9.36        -0.00264
--------------------------------------------------------------------------------------------------------------------------------------------------------

    These long and short van constants are based on GEM-simulated
tractors pulling 53-foot and solo 28-foot trailers, respectively. As a
result, aerodynamic testing to obtain a trailer's performance
parameters for Equation IV-1 must be performed using consistent trailer
sizes (i.e., aerodynamic performance for all lengths of short vans
would be tested as a solo 28-foot van, and performance for all lengths
of long vans would be tested as a 53-foot van). More information about
aerodynamic testing is provided in Section IV.E.(3)(b) below.
    The constants for long vans apply for all dry or refrigerated vans
longer than 50-feet and the constants for short vans apply for all dry
or refrigerated vans 50-feet and shorter. The vans with work-performing
devices that may be designated as partial-aero vans would use the same
equation constants as their full-aero counterparts for compliance. The
partial-aero designation simply allows a van to input different values
(i.e., lower delta CdA) and meet a different standard. Note
that compliance with the design-based standards (non-box trailers and
non-aero vans) does not require use of the GEM-based equation.
Manufacturers supply the TRRL values for their trailer tires and attest
that they installed one of the tire pressure systems (TPMS or ATIS) to
EPA for compliance.
(b) Use of the Compliance Equation for Box Van Compliance
    Box van manufacturers subject to the performance-based standards
meet the standards using the GEM-based compliance equation to combine
the effects of technologies and quantify the overall performance of the
vehicle to demonstrate compliance. Trailer manufacturers obtain delta
CdA and tire rolling resistance values from testing (either
from their own testing or from testing performed by another entity as
described in Section IV.E.(3)(b)) and attest that they installed a
qualifying tire pressure system and/or adopted weight reduction
strategies. Manufacturers adopting aerodynamic improvements will
compare their measured delta CdA value to the values shown
in Table 2 of 40 CFR 1037.515 (and Table IV-5 previously) and use the
appropriate aerodynamic bin value as the aerodynamic input into the
equation. The TRRL can be directly applied from measurements. Weight
reduction is obtained by summing applicable values in our list of light
weight components (Table 3 of 40 CFR 1037.515) or from measurements
using the off-cycle provisions. Manufacturers indicate use of TPMS or
ATIS with a specified percent reduction in CO2 and fuel
consumption.
    Qualifying components for weight reduction can be found in 40 CFR
1037.515(d). Manufacturers that substitute one or more of these
components on their box vans sum the weight reductions assigned to each
component and enter that total into the equation. As noted in Section
IV.D.(1)(d), the equation accounts for weight reduction by assigning
one-third of that reduced weight to increase the payload and the
remaining weight reduction to reduce the overall weight of the assumed
vehicle.
    Manufacturers of box vans subject to the performance standards
apply the compliance equation separately to each configuration to
ensure that all of the trailer configurations they offer need to meet
the standard for the given model year. The certification application
submitted to EPA includes equation results from the worst performing
trailer configuration for each subcategory and the manufacturer attests
that no regulated trailer will be sold in a lower performing
configuration. If the manufacturer offers a new technology package
during the model year, the performance can be evaluated using the
equation. If the performance of the new package is lower than the value
submitted in the application, the manufacturer would submit a ``running
change'' to EPA to reflect the change. Box van manufacturers will
submit a single end-of-year report that will include their production
volumes and

confirmation that all of their trailers applied the technology packages
outlined in their application.
    Any full-aero box van manufacturers that wish to take advantage of
the agencies' averaging provision in MY 2027 and later will make
greater use of the compliance equation. Before submitting a certificate
application, these manufacturers would decide which technologies to
make available for their customers and use the equation to determine
the range of performance of the packages they planned to offer. The
manufacturers would supply these results from the equation in their
certificate application and those manufacturers that wish to perform
averaging would continue to calculate emissions (and fuel consumption)
with the equation throughout the model year and keep records of the
results for each trailer package produced. As described in Section
IV.E.(1)(d) above, at the end of the year, these manufacturers would
submit two reports. One report would include their production volumes
for each configuration. The second report would summarize the families
and subfamilies, and CO2 emissions and fuel consumption
results from the equation for all of the trailer configurations they
build in that model year, including a production-weighted average to
show compliance.
    For non-box trailers and non-aero box vans, compliance is design-
based, not performance-based, and the compliance equation is not
needed. As described earlier, the standards for these trailers require
the use of tires with rolling resistance levels at or below a
threshold, and tire pressure systems (either TPMS or ATIS). Instead of
aerodynamic testing data in their certification applications,
manufacturers of these trailers submit their tire rolling resistance
levels and a description of their tire pressure system(s) to EPA.
(3) Trailer Certification Test Protocols
    The Clean Air Act specifies that compliance with emission standards
for motor vehicles be demonstrated by the manufacturer using emission
test data (see CAA section 206(a) and (b)). As discussed earlier, for
the design-based standards (non-box trailers and non-aero vans), the
trailer program considers the use of specified LRR tires and tire
pressure systems an appropriate surrogate for emission testing, and
there are no testing requirements associated with these standards
beyond the testing required to show the tires qualify as LRR tires. We
expect that tire testing will be performed by the tire manufacturers.
    All full- and partial-aero vans covered by the program are subject
to performance standards, and compliance is based on measured emission
performance. For these trailers, the program uses the GEM-based
compliance equation discussed in Section IV.E.(2)(a) above as the
official ``test procedure'' for quantifying CO2 and fuel
consumption performance for trailer compliance and certification (as
opposed to use of GEM, which serves this function in the tractor and
vocational vehicle programs). Manufacturers input performance
information from the applicable trailer technologies into the equation
in order to calculate their impact on overall trailer performance.
Manufacturers needing aerodynamic and tire rolling resistance
performance data obtain it either through their own testing or through
a device or tire manufacturer that performed the testing. The program
specifies pre-determined values for tire pressure systems and many
weight reduction components for manufacturers to apply.
    The following subsections describe the approved performance tests
for tire rolling resistance and aerodynamic drag in this trailer
program. See 40 CFR part 1037, subpart F, for a full description of the
performance tests, in particular section 40 CFR 1037.515.
(a) Trailer Tire Performance Testing
    Under Phase 1, tractor and vocational chassis manufacturers are
required to input the tire rolling resistance level (TRRL) into GEM,
and the agencies adopted the provisions in ISO 28580:2009(E) \369\ to
determine the rolling resistance of tires. The tire rolling resistance
level (TRRL) is a declared value that is based on a measured value. As
described in 40 CFR 1037.520(c), this measured value, expressed as
CRR, is required to be the result of measurements of three
different tires of a given design, giving a total of at least three
data points. Manufacturers specify a CRR value for GEM that
is less than or equal to the average of these three results. Tire
rolling resistance may be determined by either the vehicle or tire
manufacturer. In the latter case, the tire manufacturer provides a
signed statement confirming that it conducted testing in accordance
with this part.
---------------------------------------------------------------------------

    \369\ See http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=44770.
---------------------------------------------------------------------------

    The Phase 1 tire testing provisions for rolling resistance apply to
all of the regulated trailers in the Phase 2 program. In the Phase 2
program, full- and partial-aero box van manufacturers, subject to the
trailer performance-based standards, apply their declared TRRL in the
compliance equation. Non-box trailer and non-aero box vans, subject to
the design-based standards, simply report the TRRL as part of their
certification application. Based on the current practice for Phase 1,
we expect the trailer manufacturers to obtain these data from tire
manufacturers, but trailer manufacturers have the option to perform
tire testing themselves.
    The agencies requested comment on adopting a program for tire
manufacturers similar to the provision described in Section
IV.E.(3)(b)(v) for aerodynamic device manufacturers, through which tire
manufacturers would seek preliminary approval of the performance of
their trailer tires. 80 FR 40278. CARB supported this option and
further requested that EPA create a public database of the tire rolling
resistance data submitted to the agency in such preliminary approvals.
RMA's comments opposed making tire data available to the public without
first developing a rating system for medium and heavy truck tires. The
agencies have chosen not to pursue provisions for pre-approved trailer
tire rolling resistance data or a public database of this information
in this rulemaking, recognizing the overall unresolved issues relating
to standard HD truck and trailer testing within the tire industry (as
discussed in the Tractor section of this Preamble, Section
III.E(1)(e)). Instead, trailer tire manufacturers provide tire rolling
resistance values directly to the trailer manufacturers and that
information is shared with EPA and NHTSA for certification.
(b) Trailer Aerodynamic Performance Testing
    As discussed earlier, manufacturers of trailers subject to
performance standards (i.e., most box vans), need to provide EPA with
aerodynamic performance data at the time of certification. The purpose
of our trailer aerodynamic test procedures is to establish an estimate
of the aerodynamic drag experienced by a tractor-trailer vehicle in
real-world operation. We based these procedures on the current tractor
aerodynamic procedures, including coastdown, wind tunnel, and
computational fluid dynamics (CFD) modeling. More specifically, the
tests are conducted according to the same test procedures for tractors
and trailers, but different provisions apply for the test articles and
the data analysis. In the tractor program, the resulting CdA
value represents the absolute aerodynamic drag of a tested tractor
assumed to be pulling a specified standard trailer. In the trailer
program,

the tests measure the difference in CdA value between the
tested trailer as pulled by a standard tractor and a reference trailer
pulled by the same standard tractor. In other words, the trailer test
procedure is intended to measure the aerodynamic improvements rather
than the absolute aerodynamic performance. The agencies chose to base
the standards on measurements of aerodynamic improvements in part to
reflect the market reality that many trailer manufacturers rely on
manufacturers of bolt-on aerodynamic devices for the improvements
rather than redesigning their trailer or developing their own
components.
    To minimize the testing burden, the program specifies that all
aerodynamic devices for long box vans (i.e., those greater than 50-feet
in length) be evaluated based on 53-foot box vans, and that devices for
all trailers 50-feet and shorter be evaluated based on 28-foot box
vans. In other words, a manufacturer can use test data from a single
trailer to certify all trailers in the same subcategory. As noted
previously in Section IV.D.(1) and demonstrated in Chapter <IP_ADDRESS>.2.6
of the RIA, the performance of aerodynamic devices on these two trailer
lengths is expected to provide a conservative estimate of the
performance on the longer trailers within the same length category. We
believe that this compliance approach effectively represents the
performance of such devices on the majority of box vans, yet limits the
number of such vans that a manufacturer needs to track and evaluate.
    The program provides for manufacturers to have flexibility in the
devices (or packages of devices) they install on box vans with lengths
that differ from 53-feet or 28-feet. In such situations, a manufacturer
could use devices that they believe would be more appropriate for the
length of the trailer they are producing, consistent with good
engineering judgement. For example, they could test skirts on a 28-foot
trailer and use longer skirts on 40-foot trailers that they make. No
additional testing would be required in order to validate the
appropriateness of using the alternate devices on these trailers.
    The agencies have structured the final regulations to make wind
tunnel testing the primary method for measuring trailer aerodynamic
performance. While coastdown testing measures performance of full-scale
vehicles, which is generally the agencies' preference for performance
testing, wind tunnel testing achieves similar results in terms of delta
CdA, with the added benefit of measuring wind-averaged
values in the same test. In addition, wind tunnel testing is
inexpensive relative to other aero test methods and does not require as
much time to complete. Thus, it has generally been the preferred method
for the trailer industry. Nevertheless, the program provides for
manufacturers to use coastdown or CFD methods as described below and
fully in 40 CFR 1037.526(b) and 1037.150(x).
    The agencies considered making coastdown testing the primary test
method for trailers, as it is for the tractor program. However, the
delta CdA approach for the trailer aerodynamic program would
require multiple tests to evaluate most configurations. Coastdown
testing is a full-scale test method that requires the vehicle, which
includes the trailer and an appropriately aerodynamic tractor, be
driven on a road or track that meets specified conditions. An important
challenge with coastdown testing is that wind and weather restrictions
can limit the days in which testing can be performed. Additionally,
coastdown testing has higher natural variability due to environmental
variability in an uncontrolled system. We have placed an additional
restriction on the allowable difference in yaw angles for delta
CdA measurements to reduce this variability (see 40 CFR
1037.526(a)(2)). However, the combination of our test constraints
(e.g., restrictions on the wind, temperature, and road conditions), can
make it challenging to measure a drag difference from two valid
coastdown tests. These factors would make accurate coastdown testing
for the trailer program even more time-consuming and expensive relative
to the tractor program. Accordingly, we decided that wind tunnel
testing is more appropriate for this newly regulated industry.
    Coastdown testing has two significant advantages over wind tunnel
testing. First, as a full-scale method, it can be directly applied to
actual products. Second, full-scale methods may be the only way to
reliably test small-scale devices that cannot be appropriately scaled
or recreated in wind tunnel or CFD. Although these advantages justify
allowing coastdown testing as an alternate method, they do not justify
the additional costs that would occur if it were specified as the
primary test method for trailers.
    In making this determination, the agencies were cognizant of the
limited financial ability of trailer manufacturers (and device
manufacturers) to absorb testing costs. Unlike the tractor industry,
most of the manufacturers in the trailer industry are small- to medium-
sized companies. Even the largest trailer manufacturers are much
smaller than the companies that manufacture tractors. Had we
established coastdown as the primary method, trailer manufacturers
would have needed to not only perform extensive coastdown testing to
show equivalency with their preferred methods, but would have also
needed to maintain the ability to perform coastdowns on a regular basis
like tractor manufacturers are required to under Phase 1 and Phase 2,
including owning or maintaining access to an appropriate test tractor
or tractors. While this is a manageable burden for the large tractor
manufacturers, it would have been a substantial burden for trailer
manufacturers, especially the smaller ones. TTMA commented that any of
the larger manufacturers in its membership that may do testing would
prefer wind tunnel or CFD testing to ``contain costs.'' In conjunction
with the NODA, EPA laid out principles related to aerodynamic testing
that we intended to follow when applying our compliance oversight to
trailers.\370\ In particular, we indicated that we intended to rely
more on our own confirmatory testing, recognizing that both trailer
manufacturers and device manufacturers have less financial ability to
perform Selective Enforcement Audit (SEA) testing than do tractor
manufacturers (see Section IV.E.(4)(f) for more information on SEAs).
Under the final regulations, the agencies can perform wind tunnel
testing, but would also retain the right to perform coastdown testing,
provided we adjusted any coastdown results to account for yaw
differences. If we conducted confirmatory testing using coastdowns, we
would also need to perform enough runs to minimize variability between
the test conditions. Should we measure worse aerodynamic performance
(after fully adjusting for methodological differences and accounting
for test-to-test variability), we would require the manufacturer to use
our test results as the official test results. It is important to
emphasize that, because confirmatory testing generally occurs before we
have issued a certificate of conformity and before the manufacturer has
begun production, there are no penalties or other compliance actions
that would result from EPA confirmatory testing. Thus, we do not expect
manufacturers using wind tunnels to have any need to

separately verify their results using coastdown procedures.
---------------------------------------------------------------------------

    \370\ ``Additional Discussion of Selective Enforcement Audit and
Confirmatory Testing for Aerodynamic Parameters for Combination
Tractors and for Trailers,'' February 19, 2015. Docket EPA-HQ-OAR-
2014-0827-1625.
---------------------------------------------------------------------------

    Details of the test procedures can be found in 40 CFR 1037.526 and
a discussion of EPA's aerodynamic testing program as it relates to the
trailer program is provided in the RIA Chapter 3.2. The following
subsections outline the testing requirements for the long term trailer
program, as well as simpler testing provisions that apply in the nearer
term.
(i) A to B Testing for Trailer Aerodynamic Performance
    The agencies expect a majority of the aerodynamic improvements for
trailers will be accomplished by adding bolt-on technologies. As just
explained above, a key difference between the tractor program and the
trailer program is that while the tractor test procedures provide a
direct measurement of an absolute CdA value for each tractor
model, aerodynamic improvements for trailers are evaluated by measuring
a change in CdA (delta CdA) relative to a
baseline without aerodynamic improvements. Specifically, trailer tests
are performed as ``A to B'' tests, comparing the aerodynamic
performance of a tractor-trailer without a trailer aerodynamic device
(or package of devices) to one with the device (or package) installed.
As noted below, this approach can be applied if changes are made to the
aerodynamic design of a trailer as well. See RIA Chapter <IP_ADDRESS>.2 for
more justification for this A to B approach.
    In essence, an A to B test is a pair of tests: one test of a
baseline tractor-trailer in a ``no-control'' configuration with zero
trailer aerodynamic improvements (A), and one test that includes the
aerodynamic improvements to be tested (B). However, because an A test
relates to a B test only with respect to the test method and the basic
tractor-trailer vehicle, one A test could be used for many different B
test configurations. This type of testing results in a delta
CdA value instead of an absolute CdA value. For
the trailer program, the vehicle configuration in the A test includes a
standard tractor that meets specified characteristics (40 CFR
1037.501(h)), and a baseline trailer with no aerodynamic improvements.
The entity conducting the testing (e.g., the trailer manufacturer, a
contractor, or an aerodynamic device manufacturer, as discussed below)
performs the test for this configuration according to the procedures in
40 CFR 1037.526 and repeats the test for the B configuration, which
includes the trailer aerodynamic package/device(s) being tested. The
delta CdA value for that trailer with that aerodynamic
improvement is the difference between the CdA values
obtained in the A and B tests.
    The agencies note that it was relatively straightforward in Phase 1
to establish a standard trailer with enough specificity to ensure
consistent testing of tractors, since there are relatively small
differences in aerodynamic performance of base-model dry box vans.
However, as discussed in Chapter 2.10 of the RIA, small differences in
tractor design can have a significant impact on overall tractor-trailer
aerodynamic performance. An advantage of an A to B test approach for
trailers is that many of the effects due to differences in tractor
design are minimized, which allows different models of tractors to be
used as standard tractors in testing without compromising the
evaluation of the trailer aerodynamic technology. Thus, the relative
approach does not require the agencies to precisely specify a standard
tractor, nor does it require trailer manufacturers to purchase, modify
or retain a specific tractor model in order to evaluate their trailers.
    In the event that a trailer manufacturer makes major changes to the
aerodynamic design of its trailer in lieu of installing add-on devices,
it could use the same baseline trailer for the A configuration as could
be used for bolt-on features. In both cases, the baseline trailer would
be a manufacturer's standard box van. Thus, the manufacturer of a
redesigned trailer would get full credit for any aerodynamic
improvements it made.
    As discussed in Chapter 2.10 of the RIA, measured drag coefficients
and drag areas can vary slightly depending on the test method used. In
general, absolute wind-averaged CdA values measured using
wind tunnels and CFD tend to be higher than values measured using the
near-zero yaw coastdown method. The Phase 1 and Phase 2 tractor program
use coastdown testing as the reference test method, and the agencies
require tractor manufacturers to perform at least one test using that
method to establish a correction factor to apply to each of the
alternative test methods. The proposed trailer regulations referred to
coastdown as our reference method, although we noted that the size of
the bins and the use of delta CdA (as opposed to absolute
values) minimized the significance of variability between test methods.
80 FR 40280. CARB recommended that we require a reference method in our
aerodynamic testing, but provided no data to support their
recommendation.
    As noted already, the agencies have established the wind tunnel
method as the primary method. Like the tractor program, the allowance
to use alternate aerodynamic test procedures provides for adjustments
to make the measurements equivalent to the primary method. This is done
to ensure that the manufacturer is neither advantaged nor disadvantaged
by using the alternate method, relative to results they would have
obtained using the primary method. However, because determining
equivalency between methods can be burdensome, the agencies are
adopting in 40 CFR 1037.150(x) an interim allowance to use certain
specific approximations based on data currently available to us.
Manufacturers would not be required to justify using these
approximations or to seek prior approval for them. Nevertheless, in the
unlikely event that we determine that these approximations overstate
actual aerodynamic performance for a particular trailer or device, we
would not allow the manufacturer to use the approximated values for
certification and they would be required to use other more reasonable
adjustments.
    Our test results shown in Chapter 2.10 of the RIA, show that wind
tunnel and CFD produce wind-averaged delta CdA values within
the same bin for the devices tested. Thus, this interim provision
allows CFD results to be used without adjustment. Coastdown delta
CdA results, which are not wind-averaged, may be in the same
bin, but we note that the tails showed more yaw dependence and
coastdown tests under-predicted the performance of tails relative to
wind-averaged methods. We anticipate some additional current and future
devices may be sensitive to yaw angle, and our interim provision
accounts for this. Manufacturers that choose to use coastdown testing
can use their results without adjustment, or, if they suspect their
device is affected by yaw angle, they can use other testing or
analytical methods to demonstrate a means of adjusting their near-zero
yaw results to a wind-averaged equivalent 4.5-degree value. The bin
values in Section IV.E.(3)(b)(iv), which were updated based on
additional aerodynamic test data collected between the NPRM and final
rules, are based on our wind tunnel testing results, though our results
suggest that most CFD and coastdown results will fit into the same
bins. See RIA Chapter <IP_ADDRESS>.3.
(ii) Standard Tractor for Aerodynamic Testing in the Trailer Program
    The agencies are adopting a set of characteristics that qualify a
tractor to be use in trailer aerodynamic compliance testing. EPA's
trailer testing program investigated the impact of

tractor aerodynamics on the performance of trailer aerodynamic
technologies, as mentioned in Chapter <IP_ADDRESS>.2.2 of the RIA. We found
the A to B test strategy reduces the degree of precision with which the
standard tractor needs to be specified. Instead of identifying a
specific make and model of a tractor to be used over the entire
duration of the program, the agencies identified an appropriate
aerodynamic performance threshold that maintains a relatively
consistent level of performance between trailers. Tractors used in
trailer aerodynamic tests must meet Phase 2 aerodynamic Bin III or
better tractor requirements. We believe the majority of tractors in the
U.S. trucking fleet will be Bin III or better in the timeframe of this
rulemaking, and trailer manufacturers have the option to choose higher-
performing tractors in later years as tractor technology improves. See
Section III.D.2.c.i. The standard tractor for long-box vans is a Class
8 high-roof sleeper cab. The standard tractor for short box vans is a
Class 7 or 8 high roof day cab with a single drive axle (i.e., 4x2 axle
configuration). Trailer or device manufacturers are free to choose any
standard tractor that meets these criteria in their aerodynamic
performance testing. See 40 CFR 1037.501.
    The compliance equation used to determine compliance with the
trailer standards is based on GEM, so our discussion of the feasibility
of our standards (Section IV.D.(2)) includes a description of the
tractor-trailer vehicle used in GEM. The agencies proposed to require
use of a 6x4 Class 8 sleeper cab for long box van aerodynamic testing,
and a 6x4 Class 8 day cab for short box van testing. 80 FR 40279. We
believe Class 8 tractors are more widely available, which will make it
easier for the trailer industry to obtain a qualified tractor if they
choose to perform trailer testing. In order to align with the test
procedures, we also proposed to consistently model a Class 8 tractor
across all trailer subcategories in GEM. CARB supported the use of
Class 8 tractors in their comments. However, EPA encountered difficulty
in meeting the test procedure-specified tractor-trailer gap width when
using a dual drive axle day cab in one of our short box van wind tunnel
tests due to the location of the landing gear relative to the kingpin.
As a result, we are changing the standard tractor specifications for
aerodynamic testing to require the use of a 4x2 tractor for short
trailers. While we expect most manufacturers will use tractor-trailer
models in wind tunnel or CFD testing, we recognize that there are fewer
4x2 tractors available for full-scale testing, and we are adopting
provisions that testers can use either a Class 8 or Class 7 day cab
tractor to address availability concerns. We believe the external
aerodynamic characteristics of Class 7 and Class 8 day cabs are very
similar and the engine performance differences between the two tractor
classes would not impact the aerodynamic performance in terms of delta
CdA. Note that a Class 7 4x2 day cab tractor is used for all
short van default tractor-trailer vehicles within GEM and represented
in the GEM-based equation (see Table IV-8).
    Daimler requested that we choose a single tractor for all trailer
testing to ensure consistency over time. As stated above, the agencies
agree that the tractor does have the potential to influence the
aerodynamic performance of trailers. As discussed above, however, we
believe that influence is reduced with use of a delta CdA.
Additionally, we believe it would be a significant burden on the
trailer industry to require manufacturers and suppliers to acquire a
specific tractor make and model over the timeframe of the rules. Thus,
the final trailer program does not require the use of a specific
tractor make for the Phase 2 trailer program.
(iii) Accounting for Wind Impacts When Measuring Aerodynamic
Performance
    The agencies proposed to determine the delta CdA for
trailer aerodynamic performance using the zero-yaw (or head-on wind)
values from any of the approved test procedures. However, based on
comments received, we are revising the final program to be based on
wind-averaged results, similar to the tractor program. The agencies
recognize the value of wind-averaging to better reflect the performance
expected in real-world operation, but at the time of proposal, we
believed the use of a zero-yaw delta CdA would reduce the
number of tests compared to generating a wind-averaged value from a
sweep of yaw angles. Additionally, it is relatively straightforward to
generate wind-averaged CdA values from wind tunnel and CFD,
but there is a significant increase in test burden to obtain wind-
averaged results from coastdown tests. Our intent was to ensure parity
between test procedures, such that manufacturers would have the several
options to test aerodynamic performance.
    The agencies received comment on this issue, in the context of the
proposed tractor standards, suggesting that the CdA measured
at a yaw angle of 4.5 degrees is very similar to the wind-averaged
CdA calculated at 7 degrees/65 MPH. The agencies evaluated
our own test data using an average of +4.5 degrees and -4.5 degrees to
minimize the effect of potential facility asymmetry, and found that the
results were within two percent of the corresponding wind-averaged
values (See Section III.E.2.a and Chapter 3.2 of the RIA). Adoption of
this surrogate angle approach reduces the cost of generating a wind-
averaged value from wind tunnel and CFD procedures.\371\ Consequently,
the tractor program uses an average CdA measured at +4.5 and
-4.5 degree yaw angles as a surrogate wind-averaged value (see RIA
Chapter 3.2 for more information). However, it does not address the
increased burden for conducting coastdown tests.
---------------------------------------------------------------------------

    \371\ CFD test contracts are often priced for individual yaw
angles. Wind tunnel test contracts are often priced for an entire
yaw sweep. Limiting our measurement requirement to one or two yaw
angles is expected to reduce the cost of generating a wind-averaged
value from CFD, but will only reduce the cost from wind tunnel tests
if the manufacturer choses to do individual yaw angles in lieu of
the customary sweep.
---------------------------------------------------------------------------

    The agencies received comment from TTMA that ``repetitive''
coastdown testing would rarely be used by its trailer manufacturer
members. Instead, manufacturers that do choose to perform their own
testing will likely rely on CFD and wind tunnel tests. Because we are
establishing the wind tunnel method as the primary method, and because
we expect it to also be the most commonly used method, we no longer
have test burden concerns about requiring wind-averaging. Therefore,
the agencies believe we can adopt aerodynamic test procedures for
trailers that require wind-averaged delta CdA values, as
represented by an average of results from +4.5 and -4.5 degree yaw
angles, for compliance. We believe that coastdown testing will be
chosen by a small number of manufacturers and the burden of performing
this optional test on the overall industry will be relatively small.
EPA may rely on coastdown testing in its own confirmatory testing, and
the agency will accept the additional burden of correcting to a wind-
averaged value.
(iv) Bins for Aerodynamic Performance
    As mentioned in Section IV.D., the trailer program uses aerodynamic
bins to account for testing variability and to provide consistency in
the performance values used for compliance. We developed these bins in
terms of delta CdA ranges, and we designed them to be broad
enough to cover the range of uncertainty seen in our aerodynamic
testing program in terms of test-to-test variability as well as
variability due to

differences in test method, tractor models, trailer models and device
models. The bins are somewhat different than in the proposal, as
discussed in Section IV.D.(1)(a)(ii) above RIA Chapter <IP_ADDRESS>.3.

   Table IV-25--Aerodynamic Bins Used To Determine Inputs for Trailer
                              Certification
------------------------------------------------------------------------
                                                              Delta CdA
   Delta CdA measured in testing               Bin            input for
                                                              compliance
------------------------------------------------------------------------
<0.1...............................  Bin I.................          0.0
0.10-0.39..........................  Bin II................          0.1
0.40-0.69..........................  Bin III...............          0.4
0.70-0.99..........................  Bin IV................          0.7
1.00-1.39..........................  Bin V.................          1.0
1.40-1.79..........................  Bin VI................          1.4
>=1.8..............................  Bin VII...............          1.8
------------------------------------------------------------------------

    A manufacturer that wishes to perform testing first identifies a
standard tractor according to 40 CFR 1037.501(h) and a representative
baseline trailer with no aerodynamic features (or models of these
vehicles), then performs the A to B tests with and without aerodynamic
improvements to obtain a delta CdA value. The manufacturer
uses Table IV-25 to determine the appropriate bin based on their
measured delta CdA. Each bin has a corresponding delta
CdA threshold value that is the value manufacturers insert
into the compliance equation.
(v) Aerodynamic Device Testing Compliance Path
    The agencies recognize that much of the trailer manufacturing
industry may have little experience with aerodynamic performance
testing. For this reason, the program includes a compliance option that
we believe minimizes the testing burden for trailer manufacturers, and
at the same time meets the requirements of the Clean Air Act and of
EISA by providing reasonable assurance that the anticipated
CO2 and fuel consumption benefits of the program will be
realized in real-world operation. This approach provides an opportunity
for trailer manufacturers to choose technologies with pre-approved test
data for installation on their new trailers without performing their
own aerodynamic testing. We note that this testing option is consistent
with recommendations of the Small Business Advocacy Review (SBAR)
Panel, which is summarized in Section XIV.D and Chapter 12 of the RIA.
    The trailer program provides for trailer aerodynamic device
manufacturers to seek preliminary approval of the performance of their
devices (or combinations of devices) based on the same performance
tests described previously. Trailer manufacturers could then choose to
use these devices and apply the approved performance levels in the
certification application for their trailer families. A device
manufacturer would need to perform the required A to B testing using a
tractor-trailer that meets the requirements specified in 40 CFR
1037.211 and 1037.526 and submit the performance results, in terms of
delta CdA, directly to EPA.\372\ EPA would require much of
the same information from the device manufacturers as it would normally
require during certification, including the technology name, a
description of its proper installation procedure, and its corresponding
delta CdA derived from the approved test procedures. See 40
CFR 1037.211.
---------------------------------------------------------------------------

    \372\ Note that in the event a device manufacturer submits false
or inaccurate data to EPA, it could incur liability for causing a
regulated entity to commit a prohibited act. See 40 CFR 1068.101(c).
This same potential liability exists with respect to information
provided by a device manufacturer directly to a trailer
manufacturer.
---------------------------------------------------------------------------

    Once a device manufacturer has obtained this preliminary approval,
it could supply the same information to any trailer manufacturers that
wish to install its devices. When the trailer manufacturer certifies,
the agencies would merely verify that the values in the trailer
manufacturer's certification application are those already approved for
the device manufacturer. To ease the transition for MYs 2018 through
2020, we proposed and are adopting a flexibility to allow pre-approval
of certain data accepted by the EPA SmartWay aerodynamic verification
program. Section IV.E.(5)(c) below describes how a device manufacturer
can use certain test data generated for SmartWay verification as a part
of its pre-approval in the early years of the program.
    The program also allows trailer manufacturers to use multiple
devices with individually pre-approved test data on a single trailer
configuration, provided each device does not impair the effectiveness
of the other(s), consistent with good engineering judgment.\373\ 40 CFR
1037.211 outlines a process for combining the effects of multiple
devices to determine an appropriate delta CdA value for
compliance. More specifically, manufacturers would fully count the
technology with largest delta CdA value, discount the second
by 10 percent, and discount each of the remaining additional
technologies by 20 percent. This discounting acknowledges the complex
interactions that can occur among individual aerodynamic devices and
provides a conservative value for the impact of the combined devices
(see the analysis of device combinations in RIA Chapter 2.10). For
example, a manufacturer applying three separately tested devices with
delta CdA values of 0.40, 0.30, and 0.10 would calculate the
combined delta CdA as:
---------------------------------------------------------------------------

    \373\ A trailer manufacturer needs to use good engineering
judgement (as defined in 40 CFR 1068.5) in combining devices for
compliance in order to avoid combinations that are not intended to
work together (e.g., both a side skirt and an under-body device).

---------------------------------------------------------------------------
Delta CdA = 0.40 + 0.90*0.30 + 0.80*0.10 = 0.75 m\2\

    The agencies believe that discounting the delta CdA
values of individually-tested devices used as a combination provides a
modest incentive for trailer or device manufacturers to test and get
EPA pre-approval of the combination as an aerodynamic system for
compliance. To avoid this discounting, device manufacturers can test a
trailer incorporating a combination of devices and receive EPA pre-
approval for data from that combination. Trailer manufacturers could
then use the test results from that specific combination for
certification.
    Note that the aerodynamic bins of Table IV-25 do not apply to
aerodynamic data that device manufacturers submit to EPA for pre-
approval. The pre-approved data will have greater precision than the
bin-averaged values shown in Table IV-25. Therefore, trailer
manufacturers calculating a delta CdA value based on
combinations of pre-approved data use the exact numbers submitted by
the device manufacturers to calculate the discounted delta
CdA, and thus select an appropriate bin value for compliance
based on that result. The process to obtain approval is outlined in 40
CFR 1037.211.
    The agencies note that many of the largest van manufacturers are
already performing aerodynamic test procedures to some extent, and the
agencies expect other van manufacturers will increasingly be capable of
and interested in performing these tests as the program progresses. The
device testing approach is intended to allow trailer manufacturers to
focus on and become familiar with the certification process in the
early years of the program and, if they wish, begin to perform testing
in the later years, when it may be more appropriate for their
individual companies. This approach does not preclude trailer
manufacturers from performing their own testing at any time, even if
the technologies they wish to install are already pre-approved. For

example, a manufacturer that believed a specific trailer actually
performed in a more synergistic manner with a given device than the
device's pre-approved delta CdA value suggested could
perform its own testing and submit the results to EPA for
certification.
    STEMCO, an aerodynamic device manufacturer, commented in support of
the proposed pre-approval option, but also supported the agencies
publishing information about the testing performed by device
manufacturers for their devices to be pre-approved. The agencies are
not committing to publish the pre-approved aerodynamic data at this
time. We do note that once data are submitted to EPA and the device is
introduced into commerce, the data are available to the public at their
request and the information gathered may be published by outside
stakeholders.
(4) Additional Certification and Compliance Provisions
(a) Trailer Useful Life
    Section 202(a)(1) of the CAA specifies that EPA is to propose
emission standards that are applicable for the ``useful life'' of the
vehicle. NHTSA is adopting EPA's proposed useful life requirements for
trailers, to ensure that manufacturers consider in their design process
the need for fuel efficiency standards to apply for the same duration
as the EPA standards. Based on our own research and discussions with
trailer manufacturers, EPA and NHTSA are adopting a regulatory useful
life value for trailers of 10 years, as proposed. This useful life
value represents the average duration of the initial use of trailers,
before they are moved into less rigorous duty (e.g., limited use or
storage). We note that the useful life value is 10 years or a mileage
threshold for other heavy-duty vehicles. However, unlike for the other
vehicles, the program does not include a parallel mileage value for
trailers. This would require odometers on trailers, and we do not
believe that mandating odometers would be appropriate for this purpose.
    With this useful life provision, trailer manufacturers are
responsible for designing and building their trailers so that they will
be able to meet the CO2 emissions and fuel consumption
standards for 10 years after the trailer is produced, provided that
they are properly maintained. For technologies at issue here, we
believe that this requirement is essentially the same as customers'
existing durability expectations. The useful life requirements do not
include liability for damage to or removal of devices by users.
Instead, trailer manufacturers must ensure at the time of sale that
devices are properly installed and able to maintain functionality
throughout the useful life. We believe that manufacturers will be able
to demonstrate at certification that their trailers, including all
bolt-on technologies used as emissions controls, will comply with the
CO2 and fuel consumption standards for the useful life of
the trailers without separate durability testing. The aerodynamic
technologies that we expect manufacturers to use to comply with the
trailer standards, including side skirts and boat tails, are designed
to continue to provide their full potential benefit indefinitely as
long as no serious damage occurs.
    Regarding a useful life value for trailer tires, we recognize that
the original lower rolling resistance tires will wear over time and
will be replaced several times during the useful life of a trailer,
either with new or retreaded tires. As with the Phase 1 tractor
program, to help ensure that trailer owners have sufficient knowledge
of which replacement tires to purchase in order to retain the as-
certified emission and fuel consumption performance of their trailer
for its useful life, the trailer program requires that trailer
manufacturers supply adequate information in the owners manual to allow
the trailer owner to purchase replacement tires meeting or exceeding
the rolling resistance performance of the original equipment tires.
(Note that the ``owners manual'' need not be a physical document, but
could be made available on line). We believe that the favorable fuel
consumption benefit of continued use of LRR tires generally results in
proper replacements throughout the 10-year useful life. Finally, the
program requires that tire pressure systems remain effective for at
least the 10-year useful life, although some servicing may be necessary
by the customer. See also the related discussions below in Section
IV.E.(4)(c) (Emission-Related Warranty) and Section IV.E.(4)(d)
(Maintenance).
(b) Emission Control Labels
    Historically, EPA-certified vehicles are required to have a
permanent emission control label affixed to the vehicle. The label
facilitates identification of the vehicle as a certified vehicle. For
the trailer program, EPA requires that the labels include the same
basic information as we require for tractor labels in Phase 1. For
trailers, this information includes the manufacturer, a trailer
identifier such as the Vehicle Identification Number, the trailer
family and regulatory subcategory, the date of manufacture, and
compliance statements. Although the Phase 2 label for tractors does not
include emission control system identifiers (as previously required for
tractors in the Phase 1 program in 40 CFR 1037.135(c)(6)), the trailer
program requires that these identifiers be included in the trailer
labels. See 40 CFR 1037.135 for a list of general requirements for
emissions labels, which includes a reference to Appendix III for
appropriate abbreviations for trailer technologies.
(c) Emission-Related Warranty
    Section 207 (a) of the CAA requires manufacturers to warrant their
products to be free from defects that could otherwise cause non-
compliance with emission standards. For purposes of the trailer
program, EPA requires trailer manufacturers to warrant all components
that form the basis of the certification to the CO2 emission
standards. The emission-related warranty covers all aerodynamic
devices, lower rolling resistance tires, tire pressure systems, and
other components that may be included in the certification application.
Note that the emission-related warranty is completely separate from any
other warranties a manufacturer might offer.
    The trailer manufacturer needs to warrant that these emission-
related components and systems are designed to remain functional for
the warranty period. We note that this emission-related warranty, and
the trailer manufacturer's financial responsibility for repairs, does
not apply to components that are damaged in collisions or through
abuse; nor does it cover components that experience wear with normal
use. This warranty is meant to apply to defects in the product or
improper installation by the manufacturer. Based on the historical
practice of requiring emissions warranties to apply for half of the
useful life, we are adopting a warranty period for trailers of five
years for everything except tires. For trailer tires, we apply a
warranty period of one year.
    Utility and Great Dane noted in their comments that the warranty of
current ATIS that they are aware of is limited to three years. However,
we view this as a business decision by the ATIS manufacturers, rather
than as a reflection of the actual durability of the systems. With
proper maintenance, we are aware of no reason that these systems would
be unable to meet the durability requirements of the trailer program or
to be designed to last the full useful life of the trailer if properly
maintained. See the Maintenance

discussion at IV.E.(4)(d) below. We believe a five year emission-
related warranty is justified, but we note that trailer manufacturers
can specify that their warranty depends on the proper maintenance of
components. Manufacturers can offer a more generous warranty if they
choose; however, the emission-related warranty may not be shorter than
any other warranty they offer without charge for the trailer. NHTSA is
not adopting any warranty requirements relating to its trailer fuel
consumption program.
    At the time of certification, manufacturers need to supply a copy
of the warranty statement that they supply to the end customer. This
document outlines what is covered under the GHG emissions related
warranty as well as the duration of coverage. Customers also need to
have clear access to the terms of the warranty, the repair network, and
the process for obtaining warranty service.
(d) Maintenance
    In general, EPA requires that vehicle manufacturers specify
schedules for any maintenance needed to keep their product in
compliance with emission standards throughout the useful life of the
vehicle (CAA section 207(a)). For trailers, such maintenance could
include adjustments to fairings or service to tire pressure systems.
EPA believes that any such maintenance is likely to be performed by
operators to maintain the fuel savings of the components. If
manufacturers believe that the durability of their trailer's
performance is contingent on proper maintenance of these systems, they
must include a corresponding maintenance schedule in their
certification applications.
    Since lower rolling resistance tires are key emission control
components under this program, and they will likely require replacement
at multiple points within the life of a vehicle, it is important to
clarify how tires fit into the emission-related maintenance
requirements. Although the agencies encourage the exclusive use of LRR
tires throughout the life of trailers vehicles, we do not hold trailer
manufacturers responsible for the actions of end users. We do not see
this as problematic because, as noted above, we believe that trailer
end users have a genuine financial motivation for ensuring their
vehicles are as fuel efficient as possible, which includes purchasing
LRR replacement tires and that they will continue to use them once they
are accustomed to their use. Therefore, as mentioned in Section
IV.E.(4) above, to help ensure that trailer owners have sufficient
knowledge of which replacement tires to purchase in order to retain the
as-certified emission and fuel consumption performance of their
trailer, the program requires that trailer manufacturers supply
adequate information in the owners manual to allow the trailer owner to
purchase tires meeting or exceeding the rolling resistance performance
of the original equipment tires. (As discussed above, note that the
``owners manual'' need not be a physical document, but could be made
available on line). Manufacturers submit these instructions to EPA as
part of the application for certification.
(e) Post-Useful Life Modifications
    The Clean Air Act generally prohibits any person from removing or
rendering inoperative any emission control device installed for
compliance, such as those needed to comply with the requirements of 40
CFR part 1037. However, in 40 CFR 1037.655 EPA clarifies that certain
vehicle modifications are allowed after a vehicle reaches the end of
its regulatory useful life. This section applies to trailers, since it
applies to all vehicles subject to 40 CFR part 1037.
    The provisions of 40 CFR 1037.655 clarify that owners may modify a
vehicle for the purpose of reducing emissions, provided they have a
reasonable technical basis for knowing that such modification will not
increase emissions of any other pollutant, but emphasizes that EPA
presumes such modifications to be more appropriate for second owners.
In the case of trailers, an owner would need to have information that
would lead an engineer or other person familiar with trailer design and
function to reasonably believe that the modifications will not increase
emissions of any regulated pollutant. In the absence of such
information, modifications during or after the trailer's useful life
would constitute tampering with an emission control system. Thus, this
provision does not provide a blanket allowance for modifications after
the useful life.
    This section does not specifically apply with respect to
modifications that occur within the useful life period, other than to
note that many such modifications to the vehicle during the useful life
are presumed to violate CAA section 203(a)(3)(A). EPA notes, however,
that this is merely a presumption, and would not prohibit modifications
during the useful life where the owner clearly has a reasonable
technical basis for knowing the modifications will not cause the
vehicle to exceed any applicable standard.
(f) Confirmatory Testing and Selective Enforcement Audits (SEA) for GEM
Inputs
    In Phase 2, vehicle performance for box vans (except non-aero box
vans) is measured using a GEM-based equation, which accepts input
parameters related to aerodynamics, tire rolling resistance, and
trailer weight. Trailer manufacturers are responsible for obtaining
performance measures for these parameters through valid testing
according to the specified test procedures. The Clean Air Act
authorizes EPA to perform its own testing to confirm the manufacturer's
data. This testing, which is called confirmatory testing, is conducted
prior to issuing a certificate. The Act also authorizes EPA to require
manufacturers to conduct Selective Enforcement Audits (SEA), which
would involve testing performed on production vehicles before they
enter into commerce.
    The agencies are finalizing a list of lightweight trailer
components that can be installed by trailer manufacturers and used in
certification. Additionally, we are assigning a set percent reduction
value to qualifying tire pressure systems (i.e., ATIS and TPMS) that
manufacturers can apply if they install these systems. Thus, because
these are agency-default values rather than the manufacturers' measured
or declared values, we will not hold trailer manufacturers responsible
for the accuracy of these values. Additionally, we expect most trailer
manufacturers will obtain LRR tire information directly from the tire
manufacturers and many trailer manufacturers will install aerodynamic
devices with data that was pre-approved by EPA. Information provided by
a third party (such as a tire or device manufacturer) to a regulated
entity for compliance is treated as though it was submitted directly to
EPA. EPA has the authority to verify such data and hold the third party
responsible for any falsified data, since submission of such data could
incur liability for causing a regulated entity to commit a prohibited
act. See 40 CFR 1068.101(c).
    Of all of the performance measures for trailers, we believe
aerodynamic testing has the greatest potential for variability and
these results are likely to receive the most scrutiny. In the NPRM, we
proposed to generally apply the same SEA and confirmatory testing
structures to tractors and trailer with respect to aerodynamics.
However, we also proposed to retain the authority to require component
manufacturers to perform SEAs where certification relies

on their test data. See, e.g. section 1037.301(d)(4) of the proposed
regulations.
    We are revising the SEA and confirmatory testing structures for
trailers based on further consideration and comments received from the
trailer manufacturing industry (TTMA). In general, the final
regulations reflect the following principles:
     Due to the smaller number of possible trailer
configurations (compared to tractor configurations), it would be more
possible for EPA to rely on confirmatory testing for trailer
aerodynamics.
     Since test-to-test variability for individual coastdown
runs can be high, confirmatory test determinations should be based on
average values from multiple runs.
     Trailer manufacturers and trailer component manufacturers
have less financial ability to perform SEAs than do tractor
manufacturers. Nevertheless, EPA should retain the authority to require
trailer and trailer component manufacturers to perform SEAs, especially
where EPA has reason to believe the trailers are non-compliant.
     Given the limited ability to eliminate uncertainty,
compliance determinations should consider the statistical confidence
that a true value lies outside a bin.
    EPA will generally try to duplicate a manufacturer's test setup in
any confirmatory testing (which would include the standard tractor)
unless we have reason to believe an inappropriate setup was used. While
our test results presented in Chapter 2.10 of the RIA show that the
trailer program's delta CdA approach reduces the tractor's
impact on trailer results, to the extent practical, EPA will use the
same standard tractors that manufacturers used in their testing.
    We believe that, although the final compliance structure for
trailers is simpler than for tractors, it will still provide a strong
incentive for manufacturers to act in good faith. In particular, the
regulations emphasize the final value of EPA's auditing records and
inspecting production components, rather than requiring manufacturers
to perform expensive testing. Thus, EPA expects to require
manufacturers to perform SEA testing only when we have reasonable
evidence leading us to believe a manufacturer have not provided
accurate test data. See Section III.E.(2)(a)(ix) for a discussion of
how EPA would conduct an aerodynamic SEA.
(g) Importation of New Trailers
    Manufacturers have raised concerns about enforcement of emission
standards for new trailers that are imported into the United States.
This poses unique challenges at the point of entry, because new
trailers may be carrying cargo and are therefore nearly
indistinguishable from trailers that have already been imported or
otherwise placed into service. We are not adopting any new or different
compliance provisions in this rulemaking to address this; however, we
intend to work cooperatively with Customs and Border Protection and
other agencies to ensure that first-time state registration of new
trailers includes verification that the trailer manufacturers have
certified them to meet U.S. emission and fuel consumption standards. We
expect this to be similar to the current system for ensuring that new,
imported trailers meet NHTSA safety standards.
    A related concern applies for foreign-based trailers traveling in
the United States for importing or exporting cargo. Such trailers are
not subject to emission and fuel consumption standards unless they are
considered imported into the United States. U.S. cabotage law prohibits
foreign truck drivers from carrying product from one point to another
within the United States. Effective enforcement of this cabotage law
will help prevent manufacturers of noncompliant foreign-produced
trailers from gaining a competitive advantage over manufacturers of
compliant domestic trailers.
(5) Flexibilities
    The trailer program that the agencies are adopting incorporates a
number of provisions that have the effect of providing flexibility and
easing the compliance burden on trailer manufacturers while maintaining
the expected CO2 and fuel consumption benefits of the
program. Among these is the basic approach we used in setting the
trailer standards, including the staged phase-in of the standards,
which gradually increase the CO2 and fuel consumption
reductions that manufacturers need to achieve over time as they also
increase their experience with the program. As described in Section
IV.E.(3)(b)(v), another of these is the process for device
manufacturers to submit test data directly to EPA for review by the
agencies in advance of formal certification, allowing a trailer
manufacturer to reduce the amount of testing needed to demonstrate
compliance or avoid it altogether.
    In addition to these provisions inherent to the trailer program,
this section describes additional options the agencies are adopting
that we believe will be valuable to many trailer manufacturers.
(a) Limited Allowance of Non-Complying Trailers
    As described in Section IV.B. above the agencies are not finalizing
the proposed provisions that would have allowed manufacturers to comply
with the trailer standards using averaging before MY 2027. As a result,
in the absence of mitigating provisions, manufacturers would need to
comply with the applicable standards for all of their trailers. The
agencies received comment, primarily from trailer manufacturers, that,
without the flexibility of averaging, trailer manufacturers should be
allowed to ``carve-out'' a set percentage of their sales that would not
be required to meet the standards. Stoughton Trailers suggested a 20
percent carve-out.
    The agencies considered this concept and this final program
provides each manufacturer with a limited ``allowance'' of trailers
that do not need to meet the standards. In determining an appropriate
value for this allowance, the agencies sought to balance the need for
some degree of flexibility in the absence of averaging while minimizing
changes in the competitive relationships among larger and smaller
trailer manufacturers. An allowance of 20 percent, as suggested by
Stoughton, is problematic, since the annual production for individual
trailer manufacturers varies so widely. An allowance of 20 percent for
a very large manufacturer could very well represent the same volume of
trailers as an entire year's sales for a small manufacturer. This in
turn could result in a situation where a large number of non-complying
trailers would be on the market, potentially attracting customers away
from smaller manufacturers that needed to market complying trailers.
    Because of this, the agencies estimated a representative volume of
trailers based on the 2015 Trailer Production Figures published by
Trailer-BodyBuilders.com.\374\ The smallest box van manufacturer in the
list produced 1800 dry freight vans in 2015. Twenty percent of that
production is 360 trailers. The agencies are adopting an interim
provision providing box van manufacturers an allowance of 20 percent of
their production (up to a maximum of 350 units) that are not

required to meet the standards for model years 2018 through 2026 when
we do not include averaging. All lengths of box vans, including both
dry and refrigerated, produced by a given manufacturer count toward the
allowance.
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    \374\ 2015 Trailer Production Figures Table. Schenk, Paul. March
4, 2016. Accessed January 4, 2016. Available at: http://trailer-bodybuilders.com/trailer-output/2015-trailer-production-figures-table.
---------------------------------------------------------------------------

    While averaging does not apply for partial- and non-aero box
trailers at any point in the program, the agencies believe
manufacturers can also benefit from the ability to exempt some trailers
from these subcategories in the early years as they transition into the
full program. For MY 2018 through 2026, manufacturers can include
partial- and non-aero box trailers in their 350 box van allowance. In
MY 2027, we believe all partial- and non-aero box vans can meet the
reduced standards for their given subcategories.
    Non-box trailers have design-based tire standards and averaging
thus does not apply for this subcategory. Similar to the partial- and
non-aero box vans, we also believe non-box manufacturers can benefit
from a transitional exemption allowance. The agencies are adopting a
separate allowance for non-box trailers, because their production
volumes differ and many non-box trailer manufacturers do not build box
vans. Using the same trailer production figures, we found that the
smallest non-box trailer manufacturer in the list produced 1325
trailers in 2015 and twenty percent of that production is 265 trailers.
From MY 2018 through 2026, non-box trailer manufacturers can exempt 20
percent or 250 trailers from the applicable tire standards. By MY 2027,
we believe all non-box trailers can incorporate the tire technologies
required by the design standards.
    The agencies estimate that the box van and non-box trailer
allowances translate on average to less than two percent of production
across the trailer industry, and the agencies believe that this minor
degree of loss of emission and fuel consumption reduction benefits is
more than offset by the flexibility which, as pointed out earlier, may
be needed by this newly regulated industry segment. These allowances
are specified in 40 CFR 1037.150 and 49 CFR 535.3.
(b) Averaging Provisions for the Late Years of the Trailer Program
    The agencies proposed to allow trailer manufacturers to use
averaging throughout the phase-in of the program as one option for
complying with the trailer standards. As noted, we received nearly
unanimous comments, in response to the pre-proposal SBREFA panel and to
the NPRM, from trailer manufacturers opposing averaging. Specifically,
the commenters cited their concern that the unique aspects of the
trailer market tend to mean that the value of averaging as a tool is
less than it has been for manufacturers in other industries, and the
potential for negative consequences to some manufacturers is
substantial. The trailer manufacturing industry is very competitive,
and manufacturers must be highly responsive to their customers' diverse
demands. Compared to other industry sectors, they can have little
control over what kinds of trailer models their customers demand and
thus limited ability to manage the mix and volume of different
products. Additionally, one of the larger, more diverse manufacturers
could potentially supply a customer with trailers that had few if any
aerodynamic features, while offsetting this part of their business with
over-complying trailers that they were able to sell to another
customer; many smaller companies with limited product offerings might
not be able to compete for those customers.
    As a result of the many comments opposing averaging from trailer
manufacturers--the very stakeholders meant to benefit from an averaging
program--the agencies have reconsidered how averaging is incorporated
into the program. The final program does not allow averaging as a
compliance option in the early years of the program, in MY 2018 through
MY 2026. In those years, all box vans sold (beyond a manufacturer's
allowance of non-complying trailers) must meet the standards using any
combination of available technologies.
    However, the agencies have concluded that by late in the program,
the value of an averaging option to many trailer manufacturers may well
outweigh the concerns they have expressed. In addition, the final stage
of the phase-in of the standards for MY 2027 represents the most
stringent standards in the program, and additional flexibility may be
welcome by trailer manufacturers. Therefore, the final program will
provide a limited optional averaging program for MY 2027 and later
full-aero box vans. By that time, we believe that the trailer
manufacturers will be experienced and comfortable with the program, and
the industry will be more familiar with the technologies.
    The MY 2027 and later averaging provisions are identical in most
respects to those we proposed for the other Phase 2 vehicle programs.
One notable difference involves use of credits. As in the proposed
trailer program, the averaging provisions for trailers focus on each
individual model year's production. A manufacturer choosing to use the
averaging provisions could not ``bank'' compliance credits for a future
model year or ``trade'' (sell) credits to another manufacturer, since
these provisions would disproportionately benefit the few large trailer
manufacturers. Under these averaging provisions, a full-aero box van
manufacturer that produces some MY 2027 or later box vans that perform
better than required by the applicable standard could produce a number
of vans in the same family that do not meet the standards, provided
that the average compliance levels of the trailers it produces in any
given model year is at or below the applicable standards for that
family.
    As in the proposed program, averaging is only available for full-
aero box vans. The program is already designed to offer reduced
standards for box vans designated as partial-aero, and the additional
flexibility of averaging is not available. Also, averaging is
inherently incompatible with design standards for non-aero box vans and
non-box trailers, since those manufacturers cannot choose among
compliance paths.
    The agencies are adopting averaging sets for full-aero box vans
based on trailer length. Trailers in a family are certified to a single
standard, but individual trailers within the family may be grouped to
certify to a family emissions limit (FEL) that is higher or lower than
the standard, provided the production-weighted average of all FELs in a
family can be averaged to the standard or better. By allowing averaging
sets to include both refrigerated and dry vans similar length
categories, a manufacturer that over-complies, on average, in one
family, can use the credits generated toward compliance in the other
family. For example, if a manufacturer has two subfamilies in each of
its long dry and long refrigerated van families, and the over-
compliance of one dry van subfamily exceeds the under-compliance of the
other dry van subfamily, the additional over-compliance beyond the dry
van family's standard become credits that can be used to offset any
under-compliance in the refrigerated van family.
    In order to avoid backsliding with the use of averaging, the
agencies are adopting a provision to require a minimum level of
technology adoption in MY 2027 and later. No FEL can exceed the MY 2018
standard for the given trailer subcategory. For example, a manufacturer
could not over-comply on some trailers and expect to produce a fraction
of their trailers with zero

technologies installed; every trailer must, at minimum, include enough
technologies to meet the corresponding MY 2018 standard. See 40 CFR
1037.107(a)(5) and 49 CFR 535.5(e).
    As mentioned previously, manufacturers with a trailer family that
performed better than the standard at the end of the year would not be
allowed to bank credits for a future model year. However, the agencies
understand that it is possible for a manufacturer to misjudge
production and come up short at the end of the model year. In such a
case, the program provides for a manufacturer to generate a credit
deficit, if necessary, as a temporary recourse for unexpected
challenges in a given model year.\375\ The agencies would closely
monitor the certification applications for the following model year, to
ensure the manufacturer can make progress in reducing the deficit. Any
such credit deficits would need to be resolved within the following
three model years, and the manufacturer would need to generate credits
from over-compliance in subsequent years to address deficits from prior
model years. See 40 CFR 1037.745.
---------------------------------------------------------------------------

    \375\ Section IV.E.(1)(b) describes the process of identifying
trailer families and sub-families based on basic trailer
characteristics. 40 CFR 1037.710 describes the provisions for
establishing subfamilies within a trailer family and the Family
Emission Limits that are averaged among the subfamilies.
---------------------------------------------------------------------------

    The agencies believe that limiting the availability of averaging
provisions to the final stage of the program will ease a number of the
competitive concerns that trailer manufacturers have raised, since the
trailer program will be familiar and the value of averaging may be
greater as the most stringent standards phase in. Small business
manufacturers raised concerns in our pre-proposal small business
outreach that averaging would disproportionately benefit larger
manufacturers with larger production volumes and greater product
diversity. We are limiting our averaging program to single model year
averaging (i.e., no banking or trading) to help address this concern.
Similarly, we are adopting a maximum FEL based on the MY 2018 standard
to ensure that larger manufacturers will not be able to produce large
volumes of trailers with little or no technologies at the expense of
manufacturers that cannot accumulate sufficient over-compliance within
their annual production. To the extent that concerns about the MY 2027
and later averaging provisions remain as that model year approaches,
the agencies look forward to working with manufacturers as they
consider using averaging.
(c) Aerodynamic Device Testing Using SmartWay-Verified Data
    The agencies expect some trailer manufacturers and aerodynamic
device manufacturers to continue to submit test data to the SmartWay
program for verification. Since many manufacturers have some experience
with EPA's SmartWay program, the agencies have designed the trailer
program and aerodynamic testing to recognize the significant synergy
with the SmartWay Technology Program. Section IV.E.(3)(b)(v) describes
the compliance path available to trailer manufacturers to use pre-
approved performance data for aerodynamic devices. As an additional
interim option, any device manufacturer that attains SmartWay
verification for a device prior to January 1, 2018 is eligible to
submit its previous SmartWay-verified data to EPA's Compliance Division
for pre-approval, provided their test results come from one of
SmartWay's 2014 test protocols that measure a delta CdA. The
protocols for coastdown, wind tunnel, and computational fluid dynamics
analyses result in a CdA value. Note that SmartWay's 2014
protocols allow SAE J1321 Type 2 track testing, which generates fuel
consumption results, not CdA values. Two commenters (a
device manufacturer and an NGO) requested that we allow SAE J1321 track
test results, but did not suggest a means of converting from the fuel
consumption results to an appropriate delta CdA value for
use in compliance. As a result, the agencies will not accept J1321 data
for pre-approval.
    Beginning on January 1, 2018, EPA will require that device and
trailer manufacturers that seek approval of new aerodynamic
technologies for trailer certification use one of the approved test
methods for Phase 2 (i.e., coastdown, wind tunnel or CFD) and the test
procedures found in 40 CFR 1037.526. Aerodynamic technologies that were
pre-approved using performance data from SmartWay's 2014 Protocols will
maintain their approved status through December 31, 2020. Beginning
January 1, 2021, all pre-approval of device performance will need to be
based on testing using the Phase 2 test procedures.
(d) Off-Cycle Technologies
    The Phase 1 and Phase 2 programs include provisions for
manufacturers to request the use of off-cycle technologies that are not
recognized in GEM and were not in common use before MY 2010. During the
development of the trailer proposal, the agencies were not aware of any
technologies that could improve CO2 and fuel consumption
performance that would not be captured in the trailer test protocols,
and we did not propose a process to evaluate off-cycle trailer
technologies. We continue to believe that effective trailer aerodynamic
technologies that would not be captured by the test protocols are
unlikely to emerge. However, Wabash provided comments requesting a
process for evaluating future trailer weight reduction options. They
suggested that these options could include lightweight components that
are not listed in our regulations as approved material substitution
components, or overall trailer weight reduction strategies that are not
limited to individual components.
    In light of these comments and further consideration of the issue,
the agencies believe that the off-cycle technology process is an
appropriate way for certain box van manufacturers--that is, those using
the compliance equation and not subject to the design standards--to
receive credit for future lightweighting or other technologies that are
not recognized in the compliance equation. For this reason, we have
incorporated box vans into the existing off-cycle provisions. In the
case of lightweighting, a measured difference in trailer weight could
substitute for the weight component of the compliance equation. For
other such technologies (should any exist), the general off-cycle
provisions apply. See 40 CFR 1037.515(e).
(e) Small Business Regulatory Flexibility Provisions
    As a part of our small business obligations under the Regulatory
Flexibility Act, EPA and NHTSA have considered additional flexibility
provisions aimed at this segment of the trailer manufacturing industry.
EPA convened a Small Business Advocacy Review (SBAR) Panel as required
by the Small Business Regulatory Enforcement Fairness Act (SBREFA), and
much of the information gained and recommendations provided by this
process form the basis of the proposed flexibilities.\376\ As in
previous rulemakings, our justification for including provisions
specific to small businesses is that these entities generally have a
greater degree of difficulty in complying with the

standards compared to other entities. Thus, as discussed below, we are
adopting several regulatory flexibility provisions for small trailer
manufacturers that we believe will reduce the burden on them while
achieving the goals of the program.
---------------------------------------------------------------------------

    \376\ Additional information regarding the findings and
recommendations of the Panel are available in Section XIV, Chapter
12 of the RIA, and in the Panel's final report titled ``Final Report
of the Small Business Advocacy Review Panel on EPA's Planned
Proposed Rule: Greenhouse Gas Emissions and Fuel Efficiency
Standards for Medium- and Heavy-Duty Engines and Vehicles: Phase 2''
(See Docket EPA-HQ-OAR-2014-0827).
---------------------------------------------------------------------------

    The agencies identified 178 trailer and tank manufacturers for our
analysis and we believe 147 qualify as small business (i.e., less than
1000 employees).\377\ The agencies designed many of the program
elements and flexibility provisions available to all trailer
manufacturers with the large fraction of small business trailer
manufacturers in mind. For the small van manufacturers, we believe the
option to choose pre-approved aerodynamic data will significantly
reduce the compliance burden and eliminate the requirement for all
manufacturers to perform testing. We are also limiting the final non-
box trailer program to tanks, flatbeds, and container chassis. All
other non-box trailers are exempt from the Phase 2 trailer program,
with no regulatory requirements. This exemption reduces the number of
small businesses in the trailer program from 147 to 74 companies at the
time of the development of this rulemaking. With no regulatory
requirements, these companies have zero burden under the trailer
program. We are also adopting the proposed design standards for the
remaining non-box trailers, such that they can certify by installing
tire technologies only, with no testing requirements. The agencies are
also adopting provisions that would increase the number of eligible
tire pressure systems that can be installed for compliance. In addition
to ATIS, TPMS is a recognized technology in the final rulemaking.
Furthermore, the non-box trailers, which have design-based tire
standards, comply if they have either a TPMS or an ATIS, and
appropriate lower rolling resistance tires. The inclusion of the less
expensive TPMS as a tire pressure system option will improve the
availability of technologies and reduce the technology cost for many
small businesses.
---------------------------------------------------------------------------

    \377\ In the period between the SBAR Panel and Initial
Regulatory Flexibility Analysis and issuing of the final rule, the
Small Business Administration (SBA) finalized new size standards for
small business classification. For trailers, the threshold to
qualify as small changed from 500 employees to 1000 employees. We
have updated our analysis to reflect the new size standards.
---------------------------------------------------------------------------

    As noted above, the small trailer manufacturers raised concerns
that their businesses could be harmed by provisions allowing averaging,
banking, and trading of emissions and fuel consumption performance,
since they will not be able to generate the same volume of credits as
large manufacturers. The agencies are not adopting banking and trading
provisions in any part of the program, and are limiting the option to
average to manufacturers of full-aero dry and refrigerated box trailers
and delaying the averaging until MY 2027. Similarly, we are adopting a
maximum FEL based on the MY 2018 standard to ensure that larger
manufacturers will not be able to produce large volumes of trailers
with little or no technologies at the expense of manufacturers that
cannot accumulate sufficient over-compliance within their annual
production. We expect that the familiarity of the industry, including
small business manufacturers, with the trailer program by this stage of
the program, and the requirement that all trailers meet at least the MY
2018 level of control, will reduce the concerns of small manufacturer
compared to an earlier or broader averaging program.
    For all small business trailer manufacturers, the agencies are
adopting a one-year delay in the beginning of implementation of the
program, until MY 2019. We believe that this allows small businesses
additional needed lead time to make the necessary staffing adjustments
and process changes, and possibly add new infrastructure to meet the
requirements of the program. TTMA commented that all trailer
manufacturers are ``small businesses'' relative to other heavy-duty
industries and that the one-year delay would divert sales to small
businesses for that model year. Wabash argued that providing a
flexibility is not required by the RFA and not authorized by the Clean
Air Act. The agencies believe that small businesses do not have the
same resources available to become familiar with the regulations, make
process and staffing changings, or evaluate and market new technologies
as their larger counterparts. We believe a one-year delay provides
additional time for small businesses to address these issues, without a
large CO2 and fuel consumption impact or substantial
negative competitive effects. The cumulative annual production of all
of the small business box trailer manufacturers is estimated to be less
than 15 percent of the industry's total production, which is
significantly less than the annual production of the four largest
manufacturers.\378\ We expect any diverted sales for this one year will
be a small fraction of the large manufacturers' production and we are
finalizing the one-year delay for all small business trailer
manufacturers.
---------------------------------------------------------------------------

    \378\ See Figure 1-3 of Chapter 1 in the RIA comparing the 2015
trailer output from the top 28 trailer manufacturers.
---------------------------------------------------------------------------

    Chapter 12 of the RIA presents the agencies' Final Regulatory
Flexibility Analysis. In this chapter, we discuss the recommendations
of the Panel, what we proposed, and what we finalized for the small
businesses regulated in Phase 2. We also estimate the economic effect
of the rulemaking on these businesses based on their annual revenue.
Considering the flexibilities adopted in this rulemaking, our estimate
of compliance burden indicates that only 15 of the 147 small trailer
manufacturers (about 10 percent) will have an economic impact greater
than one percent of their annual revenue. Therefore, we believe the
trailer provisions in this rulemaking do not have a significant impact
on small businesses.

V. Class 2b-8 Vocational Vehicles

A. Summary of Phase 1 Vocational Vehicle Standards

    Class 2b-8 vocational vehicles include a wide variety of vehicle
types, and serve a wide range of functions. Some examples include
service for urban delivery, refuse hauling, utility service, dump,
concrete mixing, transit service, shuttle service, school bus,
emergency, motor homes, and tow trucks. In the HD Phase 1 Program, the
agencies defined Class 2b-8 vocational vehicles as all heavy-duty
vehicles that are not included in the Heavy-duty Pickup Truck and Van
or the Class 7 and 8 Tractor categories. In effect, the rules classify
heavy-duty vehicles that are not a combination tractor or a pickup
truck or van as vocational vehicles. Class 2b-8 vocational vehicles and
their engines emit approximately 17 percent of the GHG emissions and
burn approximately 17 percent of the fuel consumed by today's heavy-
duty truck sector.\379\
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    \379\ Memorandum to the Docket ``Runspecs, Model Inputs, MOVES
Code and Database for HD GHG Phase 2 FRM Emissions Modeling.''. July
2016. See also EPA's MOVES Web page at https://www3.epa.gov/otaq/models/moves/index.htm.
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    Most vocational vehicles are produced in a two-stage build process,
though some are built from the ``ground up'' by a single entity. In the
two-stage process, the first stage sometimes is completed by a chassis
manufacturer that also builds its own proprietary components such as
engines or transmissions. This is known as a vertically integrated
manufacturer. The first stage can also be completed by a chassis
manufacturer who procures all

components, including the engine and transmission, from separate
suppliers. The product completed at the first stage is generally either
a stripped chassis, a cowled chassis, or a cab chassis. A stripped
chassis may include a steering column, a cowled chassis may include a
hood and dashboard, and a cab chassis may include an enclosed driver
compartment. Many of the same companies that build Class 7 and 8
tractors also sell vocational chassis in the medium heavy- and heavy
heavy-duty weight classes. Similarly, some of the companies that build
Class 2b and 3 pickups and vans also sell vocational chassis in the
light heavy-duty weight classes.
    The second stage is typically completed by a final stage
manufacturer or body builder, which installs the primary load carrying
device or other work-related equipment, such as a dump bed, delivery
box, or utility boom. There are over 200 final stage manufacturers in
the U.S., most of which are small businesses. Even the large final
stage manufacturers are specialized, producing a narrow range of
vehicle body types. These businesses also tend to be small volume
producers. In 2011, the top four producers of truck bodies sold a total
of 64,000 units, which is about 31 percent of sales in that year.\380\
In that same year, 74 percent of final stage manufacturers produced
less than 500 units.
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    \380\ Specialty Transportation.net, 2012. Truck Body
Manufacturing in North America.
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    The businesses that act both as the chassis manufacturer and the
final stage manufacturer are those that build the vehicles from the
``ground up.'' These entities generally produce custom products that
are sold in lower volumes than those produced in large commercial
processes. Examples of vehicles produced with this build process
include fire apparatus and transit buses.
    The diversity in the vocational vehicle segment can be primarily
attributed to the variety of customer needs for specialized vehicle
bodies and added equipment, rather than to the chassis. For example, a
body builder can build either a Class 6 bucket truck or a Class 6
delivery truck from the same Class 6 chassis. The aerodynamic
difference between these two vehicles due to their bodies leads to
different in-use fuel consumption and GHG emissions. However, the
baseline fuel consumption and emissions due to the components included
in the common chassis (such as the engine, drivetrain, frame, and
tires) may be the same between these two types of vehicles.
    Owners of vocational vehicles that are upfitted with high-priced
bodies that are purpose-built for particular applications tend to keep
them longer, on average, than owners of vehicles such as pickups, vans,
and tractors, which are traded in broad markets that include many
potential secondary markets. The fact that vocational vehicles also
generally accumulate far fewer annual miles than tractors further
contributes to lengthy trade cycles among owners of these vehicles. To
the extent vocational vehicle owners may be similar to owners of
tractors in terms of business profiles, they are more likely to
resemble private fleets or owner-operators than for-hire fleets. A 2013
survey conducted by NACFE found that the trade cycle of private tractor
fleets ranged from seven to 12 years.\381\
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    \381\ See 2013 ICCT Barriers Report, Note 364 above.
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    The Phase 1 standards for this vocational vehicle category
generally apply at the chassis manufacturer level. For the same reasons
given in Phase 1, the agencies are applying the Phase 2 vocational
vehicle standards at the chassis manufacturer level.\382\
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    \382\ See 76 FR 57120.
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    The Phase 1 regulations prohibit the introduction into commerce of
any heavy-duty vehicle without a valid certificate or exemption. 40 CFR
1037.622, originally codified as 40 CFR 1037.620, allows for a
temporary exemption for the chassis manufacturer if it produces the
chassis for a secondary manufacturer that holds a certificate. The
agencies received several comments on the requirements for secondary
manufacturers. A discussion of temporary exemptions and obligations of
secondary manufacturers can be found in Section V.D.(2).
    In Phase 1, the agencies adopted two equivalent sets of standards
for Class 2b-8 vocational vehicles. For vehicle-level (chassis)
emissions, EPA adopted CO2 standards expressed in grams per
ton-mile. For fuel efficiency, NHTSA adopted fuel consumption standards
expressed in gallons per 1,000 ton-miles. The Phase 1 engine-based
standards vary based on the expected weight class and usage of the
vehicle into which the engine will be installed. We adopted Phase 1
vehicle-based standards that vary according to one key attribute, GVWR,
based on the same groupings of vehicle weight classes used for the
engine standards--light heavy-duty (LHD, Class 2b-5), medium heavy-duty
(MHD, Class 6-7), and heavy heavy-duty (HHD, Class 8).
    In Phase 1, the agencies defined a special regulatory category
called vocational tractor, which generally operate more like vocational
vehicles than line haul tractors.\383\ As described above in Section
III.C.4, under the Phase 1 rules, a vocational tractor is certified
under standards for vocational vehicles, not those for tractors. In
Phase 2, the agencies are revising the vocational tractor definition to
remove heavy-haul tractors, as we are adopting tractor standards for
these. The agencies received many comments pertaining to vocational
tractors, which are described in Section III.C.4 and Section V.B.
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    \383\ See EPA's regulation at 40 CFR 1037.630 and NHTSA's
regulation at 49 CFR 523.2.
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    Manufacturers are required to use GEM to determine compliance with
the Phase 1 vocational vehicle standards, where the primary vocational
vehicle manufacturer-generated input is the measure of tire rolling
resistance. The GEM assumes the use of a typical representative,
compliant engine in the simulation, resulting in one overall value for
CO2 emissions and one for fuel consumption. The
manufacturers of engines intended for use in vocational vehicles are
subject to separate Phase 1 engine-based standards. Manufacturers also
may demonstrate compliance with the CO2 standards in whole
or in part using credits reflecting CO2 reductions resulting
from technologies not reflected in the GEM testing regime. See 40 CFR
1037.610.
    In Phase 1, EPA and NHTSA also adopted provisions designed to give
manufacturers a degree of flexibility in complying with the standards.
Most significantly, we adopted an ABT program to allow manufacturers to
comply on average within a given averaging set. See 40 CFR part 1037,
subpart H. These provisions enabled the agencies to adopt overall
standards that are more stringent than we could have considered with a
less flexible program.\384\
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    \384\ As noted earlier, NHTSA notes that it has greater
flexibility in the HD program to include consideration of credits
and other flexibilities in determining appropriate and feasible
levels of stringency than it does in the light-duty CAFE program.
Cf. 49 U.S.C. 32902(h), which applies to light-duty CAFE but not to
heavy-duty fuel efficiency under 49 U.S.C. 32902(k).
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B. Phase 2 Standards for Vocational Vehicles

    Since proposal, in addition to considering substantive written
public comments, the agencies have held dozens of meetings with
manufacturers, suppliers, non-governmental organizations (NGOs), and
other stakeholders to better understand the opportunities and
challenges involved with regulating vocational vehicles. These meetings
have helped us to better

develop final Phase 2 standards. As an example, we have updated our
industry characterization to better describe the vocational vehicle
market, including the custom chassis manufacturers.\385\ We believe
these information exchanges have enabled us to develop these rules with
an appropriate balance of achievable reductions at reasonable cost with
a reasonably small risk of unintended consequences.
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    \385\ See Chapter 1 of the RIA.
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(1) Final Subcategories and Test Cycles
    The Phase 2 vocational vehicle standards are based on the
performance of a wider array of control technologies than the Phase 1
rules. In particular, as proposed, the Phase 2 vocational vehicle
standards recognize detailed characteristics of powertrains and
drivelines. As described below, driveline improvements present a
significant opportunity for reducing fuel consumption and
CO2 emissions from vocational vehicles. However, there is no
single package of driveline technologies that will be equally suitable
for the majority of vocational vehicles, because there is an extremely
broad range of driveline configurations available in the market. This
is due in part to the variety of build processes, ranging from a
purpose built custom chassis to a commercial chassis that may be
intended as a multi-purpose stock vehicle. Further, the wide range of
applications and driving patterns of these vehicles leads manufacturers
to offer a variety of drivelines, as each performs differently in use.
For example, depending on whether the transmission has an overdrive
gear, drive axle ratios for Class 7 and 8 tractors can generally be
found in the range of 2.5:1 to 4.1:1. By contrast, across all types of
vocational vehicles, drive axle ratios can range from 3.1:1 (delivery
vehicle) to 9.8:1 (transit bus).\386\ Other components of the driveline
also have a broader range of product in vocational vehicles than in
tractors, including transmission gears, tire sizes, and engine speeds.
Each of these design features affects the GHG emission rate and fuel
consumption of the vehicle. It therefore is reasonable to define more
than one baseline configuration of vocational vehicle, to encompass a
range of drivelines. A detailed list of the technologies the agencies
project could be adopted to meet the vocational vehicle standards is
described in Section V.C, and in the RIA Chapter 2.9, along with a
description of the differences in technology effectiveness that are
projected to be demonstrated through GEM under different test cycles.
The agencies have found that the ranges of effectiveness of a majority
of the technologies are significant enough to merit creation of
subcategories with different test cycles.
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    \386\ See Dana Spicer Drive Axle Application Guidelines,
available at http://www.dana.com/wps/wcm/connect/133007004bd8422b9ea8be14e7b6dae0/DEXT-daag2012_0712_DriveAxlesAppGuide_LR.pdf?MOD=AJPERES&CONVERT_TO=url&CACHEID=133007004bd8422b9ea8be14e7b6dae0. See also ZF Driveline and
Chassis Technology brochure, available at http://www.zf.com/media/media/en/document/corporate_2/downloads_1/flyer_and_brochures/bus_driveline_technology_flyer/Busbroschuere_12_DE_final.pdf.
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(a) Basis for Duty Cycles and Subcategories
    The agencies are relying on work conducted by the U.S. Department
of Energy at the National Renewable Energy Laboratory (NREL), as well
as duty cycle information provided in public comments, in establishing
the weighting factors for the test cycles to be used in the
certification of heavy-duty vocational vehicles to the final Phase 2
standards. NREL's methodology and findings are described in a report in
the docket for this rulemaking.\387\ The data from NREL have also
informed our segmentation process, and to some extent the technology
assessment. For example, without data regarding the amount of parked
idle observed by vocational vehicles in the NREL database, we would not
have been able to sufficiently identify and recognize technologies that
separately reduce either drive idle or parked idle emissions.\388\
Based on available fleet data, NREL identified three general clusters
of vehicle behavior: one cluster of vehicles most often driving with
slower speeds and frequent stops; one with higher average speeds and
fewer stops; and one multi-modal cluster with vehicles that may operate
similarly to either of the other clusters on any given day. In Chapter
2.2 of the NREL report, an alternate bi-modal clustering analysis is
also presented, where instead of having a distinct middle cluster,
vehicles with highly variable driving patterns are grouped as either
high speed or low speed. A preliminary update provided by NREL includes
cycle weightings that correspond with this two cluster depiction of
vehicle behavior.\389\ Based on the NREL report and other information,
the agencies believe it is appropriate to finalize a regulatory
subcategory structure that includes a drive cycle appropriate for mixed
use vehicles; especially considering that the ultimate application of
incomplete chassis is unknown at the time of certification. In other
words, we are adopting a program structure that follows NREL's three
cluster depiction of vehicle behavior. The final rules' primary
vocational standards thus have subcategories for Regional, Multi-
purpose, and Urban drive cycles in each of the three weight classes
(LHD, MHD and HHD), which results in nine unique subcategories.