trailers designed to transport liquids or gases. For example, DOT 406,
DOT 407, and DOT 412 tanks would fit this definition. These non-box
trailers can be pressurized or designed for atmospheric pressure. Tanks
that are infrequently used in transport and primarily function as
storage vessels for liquids or gases (e.g., frac tanks) are not
included in our definition of tank trailers and are excluded from the
program.
    Flatbed trailers for purposes of the trailer program are platform
trailers with a single, continuous load-bearing surface that runs from
the rear of the trailer to at least the trailer's kingpin. Flatbed
trailers are designed to accommodate side-loading cargo, and this
definition includes trailers that use bulkheads, one or more walls,
curtains, straps or other devices to restrain or protect cargo while
underway. Note that drop deck and lowboy platform trailers are not
considered continuous load-bearing surfaces.
    Finally, in the trailer program, container chassis are trailers
designed to transport temporary containers. The standards apply to all
lengths of container chassis, including expandable versions. The
regulations do not apply to the containers being transported, unless
they are permanently mounted on the chassis.
(c) Excluded Trailers
    As in the proposal (80 FR 40259), the final trailer program
completely excludes certain trailer types. However, in response to
comments and an improved understanding of the industry, the agencies
have changed our approach to excluding some trailer types.
    In the proposal, we focused on excluding trailers based on
characteristics that tended to indicate predominant operation in off-
highway applications. The American Trucking Associations (ATA) and the
Truck Trailer Manufacturers Association (TTMA) provided comments
suggesting that additional trailer types should be excluded from the
program based on the trailers' typical operational characteristics,
generally because of these trailers' limited on-highway operation.
Also, Wabash requested that the program specify clearer criteria for
excluding or exempting trailers.
    The agencies considered all of the suggestions of the commenters,
and we now believe that a different approach to excluding some trailer
types is more appropriate. We recognize that many trailer types in the
proposed non-box subcategory have many unique physical characteristics
and are designed for specialized operations and it would be difficult
to create a comprehensive list of traits that indicated off-road use.
This wide array of trailer types would have made the proposed approach
difficult to implement for both trailer manufacturers and for the
agencies, since the usage patterns of many specialty trailer types can
vary greatly. Some of these uses, especially off-highway applications,
may make use of the proposed tire technologies for compliance difficult
or infeasible and may limit their effectiveness. Additionally, the
agencies are aware that many manufacturers that build these specialty
non-box trailers are small businesses (fewer than 1000 employees), and
they would incur a disproportionately large financial burden compared
to larger manufacturers if they were subject to the standards.
    For these reasons, instead of focusing our approach to excluding
trailer types on trailer characteristics that indicated predominant
off-highway use, the final program excludes all non-box trailer types
except for three specific types that we believe are designed for and
mostly used in on-road applications. These types are tanks, flatbeds,
and container chassis, as defined in the previous sub-section. We now
consider this approach to be much clearer and more straightforward to
implement than the proposed approach. Manufacturers of these types of
trailers can easily obtain and install LRR tires and tire pressure
systems, and achieve the most consistent benefit from use of these
technologies. The trailer program excludes all trailers that do not
meet the criteria outlined in Section IV.C.(1)(b) above, and specified
in 40 CFR 1037.5 and in 49 CFR 535.3(e).
    The final rule also excludes certain types of trailers based on
design

characteristics, consistent with the proposed rule. More precisely,
these excluded trailer types are sub-types of otherwise regulated
trailer types, such as certain types of box vans. First, the rule
excludes trailers intended to haul very heavy loads, as indicated by
the number of axles. Specifically, the rules exclude all trailers with
four or more axles, and trailers less than 35 feet long with three
axles. For example, a 53-foot box van with four axles would be
excluded. Also, we agree with Utility that spread-axle trailers may be
more susceptible to tire scrubbing, and the program accordingly
excludes trailers with an axle spread of at least 120 inches between
adjacent axle centerlines. The axle spread exclusion does not apply to
trailers with adjustable axles that have the ability to be spaced less
than 120 inches apart. Finally, the rules exclude trailers intended for
temporary or permanent residence, office space, or other work space,
such as campers, mobile homes, and carnival trailers.\340\
---------------------------------------------------------------------------

    \340\ Secondary manufacturers who purchase incomplete trailers
and complete their construction to serve as trailers are subject to
the requirements of 40 CFR 1037.620 and 49 CFR 535.5(e).
---------------------------------------------------------------------------

    Manufacturers of excluded trailers have no reporting or other
regulatory requirements under the trailer program. See 40 CFR 1037.5
and 49 CFR 535.3 for complete definitions of the trailer types that the
program excludes. However, where the criteria for exclusion identified
above may be unclear for specific trailer models, manufacturers are
encouraged to ask the agencies to make a determination before
production begins.
(2) Fuel Consumption and CO2 Standards
    As described previously in Section I, it is the combination of the
tractor and the trailer that form the useful vehicle, and trailer
designs substantially affect the CO2 emissions and fuel
consumption of the tractors pulling them. Note that although the
agencies are adopting new CO2 and fuel consumption standards
for trailers separately from tractors, we set the numerical level of
the trailer standards (see Section IV.D. below) based on operation with
``standard'' reference tractors in recognition of their
interrelatedness. In other words, the regulatory standards refer to the
simulated emissions and fuel consumption of a standard tractor pulling
the trailer being certified.
    Unlike the other sectors covered by this Phase 2 rulemaking,
trailer manufacturers do not have experience certifying under the Phase
1 program (or under EPA's criteria pollutant program). Moreover, a
large fraction of the trailer industry is composed of small businesses
and even the largest trailer manufacturers do not have the same
resources available to them as do manufacturers in some of the other
heavy-duty sectors. The standards and compliance regime for trailers
have been developed with this in mind, and we are confident these
standards can be achieved and demonstrated by manufacturers who lack
prior experience implementing such standards.
    The agencies designed this trailer program to ensure a gradual
progression of both stringency and compliance requirements in order to
limit the impact on this newly-regulated industry. The agencies are
adopting progressively more stringent standards in three-year stages
leading up to the MY 2027,\341\ and are including several options to
reduce compliance burden in the early years as the industry gains
experience with the program (see Section IV.E.). EPA will initiate its
program in MY 2018 with standards for long box dry and refrigerated
vans, which standards can be met with common tire technologies and
SmartWay-verified aerodynamic devices and standards for the other
regulated trailers based on tire technologies only. In this early
stage, we expect that manufacturers of trailers in the other trailer
subcategories will meet their standards by using tire technologies
only. NHTSA's regulations will be voluntary until MY 2021 as described
in Section IV.C.(2).
---------------------------------------------------------------------------

    \341\ These stages are consistent with NHTSA's stability
requirements under EISA.
---------------------------------------------------------------------------

    Standards for the next stages, which begin in MY 2021, gradually
increase in stringency for each subcategory, including the introduction
of standards for short box vans that we expect will be met by applying
both aerodynamic and tire technologies. The standards for partial-aero
box vans are less stringent than those for full-aero box vans,
reflecting that the standards for partial-aero vans are based on
adoption of a single aerodynamic device throughout the program. This is
in contrast to the proposed standards for partial-aero vans that were
identical to the standards for full-aero vans through MY 2026.
    Table IV-2 and Table IV-3 below present the CO2 and fuel
consumption standards, beginning in MY 2018 that the agencies are
adopting for full- and partial-aero box vans, respectively. The
standards are expressed in grams of CO2 per ton-mile and
gallons of fuel per 1,000 ton-miles to reflect the load-carrying
capacity of the trailers.

               Table IV-2--Trailer CO[ihel2] and Fuel Consumption Standards for Full-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
                                   Subcategory                Dry van                    Refrigerated van
          Model year           ---------------------------------------------------------------------------------
                                     Length            Long            Short           Long            Short
----------------------------------------------------------------------------------------------------------------
2018-2020.....................  EPA Standard....            81.3           125.4            83.0           129.1
                                (CO[ihel2] Grams
                                 per Ton-Mile)
                                Voluntary NHTSA          7.98625        12.31827         8.15324        12.68173
                                 Standard.
                                (Gallons per
                                 1,000 Ton-Mile)
2021-2023.....................  EPA Standard....            78.9           123.7            80.6           127.5
                                (CO[ihel2] Grams
                                 per Ton-Mile)
                                NHTSA Standard..         7.75049        12.15128         7.91749        12.52456
                                (Gallons per
                                 1,000 Ton-Mile)
2024-2026.....................  EPA Standard....            77.2           120.9            78.9           124.7
                                (CO[ihel2] Grams
                                 per Ton-Mile)
                                NHTSA Standard..         7.58350        11.87623         7.75049        12.24951
                                (Gallons per
                                 1,000 Ton-Mile)
2027+.........................  EPA Standard....            75.7           119.4            77.4           123.2
                                (CO[ihel2] Grams
                                 per Ton-Mile)
                                NHTSA Standard..         7.43615        11.72888         7.60314        12.10216
                                (Gallons per
                                 1,000 Ton-Mile)
----------------------------------------------------------------------------------------------------------------

             Table IV-3--Trailer CO[ihel2] and Fuel Consumption Standards for Partial-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
                                   Subcategory                Dry van                    Refrigerated van
          Model year           ---------------------------------------------------------------------------------
                                     Length            Long            Short           Long            Short
----------------------------------------------------------------------------------------------------------------
2018-2020.....................  EPA Standard....            81.3           125.4            83.0           129.1
                                (CO[ihel2] Grams
                                 per Ton-Mile)
                                Voluntary NHTSA          7.98625        12.31827         8.15324        12.68173
                                 Standard.
                                (Gallons per
                                 1,000 Ton-Mile)
2021+.........................  EPA Standard....            80.6           123.7            82.3           127.5
                                (CO[ihel2] Grams
                                 per Ton-Mile)
                                NHTSA Standard..         7.91749        12.15128         8.08448        12.52456
                                (Gallons per
                                 1,000 Ton-Mile)
----------------------------------------------------------------------------------------------------------------

    The agencies are not adopting CO2 or fuel consumption
standards predicated on aerodynamic improvements for non-box trailers
or non-aero box vans at any stage of this program. Instead, we are
adopting design standards that require manufacturers of these trailers
to adopt specific tire technologies and thus to comply without
aerodynamic devices. This approach significantly limits the compliance
burden for these manufacturers, especially if they do not also
manufacture box vans subject to the aerodynamic requirements. The
agencies are adopting these design standards in two stages. In MY 2018,
the non-box trailer standards require manufacturers to use tires
meeting a rolling resistance of 6.0 kg/ton or better and to install
tire pressure systems. In MY 2021, non-box trailers will also need tire
pressure systems and LRR tires at 5.1 kg/ton (the current SmartWay-
verification threshold) or better. The standards require non-aero box
vans, which we believe are largely at a baseline rolling resistance 6.0
kg/ton today, to install tire pressure monitoring systems and tires at
a rolling resistance of 5.1 kg/ton in MY 2018 and 4.7 kg/ton in MY 2021
and later (there are no further increases in standard stringency for
these trailers after MY 2021). For non-box trailers and non-aero box
vans, manufacturers may install either TPMS or ATIS for compliance.
    Table IV-4 summarizes the two stages of these design standards.

               Table IV-4--Design-Based Tire Standards for Non-Box Trailers and Non-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
               Model year                          Tire technology           Non-box trailers  Non-aero box vans
----------------------------------------------------------------------------------------------------------------
2018-2020...............................  Tire Rolling Resistance Level                  6.0                5.1
                                           (kg/ton).
                                          Tire Pressure System............      TPMS or ATIS       TPMS or ATIS
2021+...................................  Tire Rolling Resistance Level                  5.1                4.7
                                           (kg/ton).
                                          Tire Pressure System............      TPMS or ATIS       TPMS or ATIS
----------------------------------------------------------------------------------------------------------------

    The agencies project that the standards for the entire class of
regulated trailers, when fully implemented in MY 2027, will achieve
fuel consumption and CO2 emissions reductions of two to nine
percent relative to mostly market-driven adoption absent a national
regulatory program (see Section IV.D.(2)). Because of the rapid pace of
technological improvement in recent years and the lead time of nearly a
decade, the agencies expect that both trailer designs and bolt-on
CO2- and fuel consumption-reducing technologies will advance
well beyond the performance of their present-day counterparts.
Regardless, we expect that the MY 2027 standards for full-aero box vans
could be met with high-performing aerodynamic and tire technologies
largely available in the marketplace today. A description of
technologies that the agencies considered in developing these rules is
provided in Section IV.D., with additional details in RIA Chapter 2.10.
(3) Non-CO2 GHG Emissions From Trailers
    In addition to the impact of trailer design on the CO2
emissions of tractor-trailer vehicles, EPA recognizes that refrigerated
trailers can also be a source of emissions of HFCs. Specifically, HFC
refrigerants that are used in transport refrigeration units (TRUs) have
the potential to leak into the atmosphere.
    In their comments, CARB said they believed that EPA underestimated
the potential for TRU refrigerant leakage, and requested that EPA (1)
initiate a TRU refrigerant ``usage monitoring program'' to support
future evaluations of leakage; (2) create incentives for low- and zero-
emission (e.g., cryogenic) TRUs; and (3) for EPA's SNAP program to
phase out the main TRU refrigerant (R404a) when viable alternatives are
available. EPA did not propose any action related to TRUs in this rule,
and CARB did not provide sufficient information for EPA to introduce
new regulatory requirements for TRUs at this time. In general, however,
EPA will continue to monitor the state of TRU technology and operation,
and may pursue appropriate action if warranted in the future.
    We also note that EPA has separately proposed a regulation under
Title VI of the CAA, specifically section 608. See 80 FR 69457
(November 9, 2015). This proposal would extend existing regulations on
ozone depleting refrigerants to many alternative refrigerants, such as
HFCs, which are the most common refrigerants used in TRUs.\342\ If
finalized as proposed, EPA would require that appliances like TRUs be
subject to the applicable requirements of 40 CFR subpart F, including
requirements for servicing by a certified technician using certified
recovery equipment and for recordkeeping by technicians disposing of
such appliances with a charge size between five and fifty pounds, which

would include TRUs, to help ensure that the refrigerant is not
vented.\343\
---------------------------------------------------------------------------

    \342\ Under the proposal, the regulations would not be extended
to equipment using a substitute refrigerant when that use of the
refrigerant has been exempted from the venting prohibition, as
listed in 40 CFR 82.154(a).
    \343\ The Clean Air Act (42 U.S.C. 7671) uses the term
``appliance'' to refer to TRUs and other similar equipment.
---------------------------------------------------------------------------

(4) Lead-Time Considerations
    As mentioned earlier, although the agencies did not include
standards for trailers in Phase 1, box van manufacturers have been
gaining experience with CO2- and fuel consumption-reducing
technologies over the past several years, and the agencies expect that
trend to continue, due in part to EPA's SmartWay program and
California's Tractor-Trailer Greenhouse Gas Regulation. Most
manufacturers of 53-foot box vans have some experience installing these
aerodynamic and tire technologies for customers. Manufacturers of
trailers other than 53-foot box vans do not have the benefit of
programs such as SmartWay to provide a reliable evaluation and
promotion of aerodynamic technologies for those trailers and therefore
have less experience with those technologies. However, all trailer
manufacturers have experience installing tires and the installation
process does not change with the use of lower rolling resistance tires.
Some manufacturers may not have direct experience with tire pressure
systems, but we observe that they are mechanically fairly simple and
can be incorporated into trailer production lines without significant
process changes.
    EPA is adopting CO2 emission standards for long box vans
for MY 2018 that represent stringency levels similar to the current
performance level needed for SmartWay's verification and those required
for the current California regulation. These standards can be met by
adopting off-the-shelf aerodynamic and tire technologies available
today. The agencies are adopting less stringent requirements for
manufacturers of other highway trailer subcategories beginning in MY
2018 that can be met without use of aerodynamic technologies. Given
that these technologies are readily available and are already familiar
to the industry, the agencies believe, for both cases, that
manufacturers have sufficient lead time to adopt these technologies and
to implement the simplified compliance provisions introduced below and
described fully in Section IV.E.
    NHTSA's direction under EISA is to allow four model years of lead-
time for new fuel consumption standards, regardless of the stringency
level or availability of flexibilities. Therefore, NHTSA's fuel
consumption requirements are not mandatory until MY 2021. Prior to MY
2021, trailer manufacturers could voluntarily participate in NHTSA's
program, noting that once they made such a choice, they will need to
stay in the program for all succeeding model years.\344\
---------------------------------------------------------------------------

    \344\ NHTSA adopted a similar voluntary approach in the first
years of Phase 1 (see 76 FR 57106).
---------------------------------------------------------------------------

    We believe there are technology pathways available today that
manufacturers could use to comply with the standards when they are
fully implemented in MY 2027. The agencies designed each three-year
stage of the program as a gradual progression of stringency that
provides sufficient lead-time for all affected trailer manufacturers to
evaluate and adopt CO2- and fuel consumption-reducing
technologies or design trailers to meet these standards while meeting
their customers' needs. The agencies believe that the burdens of
installing and marketing these CO2- and fuel consumption-
reducing technologies at the stringency levels of this program are not
limiting factors in determining necessary lead-time for manufacturers
of these trailers. Instead, we expect that the first-time compliance
and, in some cases, performance testing, will be more challenging
obstacles for this newly regulated industry. For these reasons, the
standards phase in over a period of nine years, with flexibilities to
minimize the compliance and testing burdens especially in the early
years of the program (see Section IV.E.). We are adopting provisions
for manufacturers to use a GEM-based compliance equation in lieu of the
GEM vehicle simulation tool, which will reduce the number of resources
required to learn and implement the model. We are also finalizing
compliance provisions that allow trailer manufacturers to use pre-
approved aerodynamic test data from aerodynamic device manufacturers,
which could eliminate a trailer manufacturer's test burden for
compliance. As explained above, non-aero box vans and non-box trailers,
which make up almost 20 percent of the regulated trailers, are subject
to straightforward design-based tire standards throughout the program
that require that they install qualified LRR tires and tire pressure
systems with simplified compliance requirements. See Section IV.E. for
a full description of the trailer compliance program.
    The Rubber Manufacturers Association (RMA) expressed concern that
the proposed program would not provide sufficient lead time for the
development and production of LRR tire designs for some off-road
applications. As discussed above, the final program now excludes all
trailer types that would generally be used in off-road applications,
including all non-box trailers except tanks, flatbeds, and container
chassis. Therefore, trailer types designed for off-road use do not have
LRR tire requirements, and the final program should significantly
reduce RMA's concerns about available lead time for special tire
development. Additionally, we have adjusted the tire performance
requirements for the LRR tires of the non-box trailer design standards.

D. Feasibility of the Trailer Standards

    As discussed below, the agencies' determination is that the
standards presented in Section IV.C.(2), are the maximum feasible and
appropriate under the agencies' respective authorities, considering
lead time, cost, and other factors. We summarize our analyses in this
section, and describe them in more detail in RIA Chapter 2.10.
    Our analysis of the feasibility of the CO2 and fuel
consumption standards is based on technology cost and effectiveness
values collected from several sources. Our assessment of the trailer
program is based on information from:

--Southwest Research Institute evaluation of heavy-duty vehicle fuel
efficiency and costs for NHTSA,\345\
---------------------------------------------------------------------------

    \345\ Reinhart, T.E. (June 2015). Commercial Medium- and Heavy-
Duty Truck Fuel Efficiency Technology Study--Report #1. (Report No.
DOT HS 812 146). Washington, DC: National Highway Traffic Safety
Administration.
---------------------------------------------------------------------------

--2010 National Academy of Sciences report of Technologies and
Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty
Vehicles,\346\
---------------------------------------------------------------------------

    \346\ Committee to Assess Fuel Economy Technologies for Medium-
and Heavy-Duty Vehicles; National Research Council; Transportation
Research Board (2010). Technologies and Approaches to Reducing the
Fuel Consumption of Medium- and Heavy-Duty Vehicles. (``The NAS
Report'') Washington, DC, The National Academies Press. Available
electronically from the National Academy Press Web site at http://www.nap.edu/catalog.php?record_id=12845.
---------------------------------------------------------------------------

--TIAX's assessment of technologies to support the NAS panel
report,\347\
---------------------------------------------------------------------------

    \347\ TIAX, LLC. ``Assessment of Fuel Economy Technologies for
Medium- and Heavy-Duty Vehicles,'' Final Report to National Academy
of Sciences, November 19, 2009.
---------------------------------------------------------------------------

--The analysis conducted by the Northeast States Center for a Clean Air
Future, International Council on Clean Transportation, Southwest
Research Institute and TIAX for reducing fuel consumption of heavy-

duty long haul combination tractors (the NESCCAF/ICCT study),\348\
---------------------------------------------------------------------------

    \348\ NESCCAF, ICCT, Southwest Research Institute, and TIAX.
Reducing Heavy-Duty Long Haul Combination Truck Fuel Consumption and
CO2 Emissions. October 2009.
---------------------------------------------------------------------------

--The technology cost analysis conducted by ICF for EPA,\349\ and
---------------------------------------------------------------------------

    \349\ ICF International. ``Investigation of Costs for Strategies
to Reduce Greenhouse Gas Emissions for Heavy-Duty On-Road
Vehicles.'' July 2010. Docket Number EPA-HQ-OAR-2010-0162-0283.
---------------------------------------------------------------------------

--Testing conducted by EPA.

    As an initial step in our analysis, we identified the extent to
which fuel consumption- and CO2-reducing technologies are in
use today. The technologies include those that reduce aerodynamic drag
at the front, back, and underside of trailers, tires with lower rolling
resistance, tire pressure technologies, and weight reduction through
component substitution. For our feasibility analysis, we identified a
set of technologies to represent the range of those likely to be used
in the time frame of the rule. The agencies developed the
CO2 and fuel consumption standards for each stage of the
program by combining the projected effectiveness of trailer
technologies and the projected adoption rates for each trailer type. It
should be noted that the agencies need not and did not attempt to
predict the exact future pathway of the industry's response to the new
performance standards for box vans. Rather, we demonstrated one example
compliance pathway that could reasonably occur, taking into account
cost of the standards (including costs of compliance testing and
certification), and needed lead time. More details regarding our
analysis can be found in Chapter 2.10 of the RIA.
(1) Technological Basis of the Standards
    Trailer manufacturers can design a trailer to reduce fuel
consumption and CO2 emissions by addressing the trailer's
aerodynamic drag, tire rolling resistance, and weight. Accordingly, the
agencies investigated aerodynamic technologies (e.g., skirts and
tails), low rolling resistance tires, tire pressure systems, and
materials that could be used to reduce trailer weight. A description of
these technologies, including their expected performance, can be found
in Chapter 2.10.2 of the RIA. For box vans, the analysis below presents
one possible set of technology designs by which trailer manufacturers
could reasonably achieve the standards. However, in practice, trailer
manufacturers could choose different technologies, versions of
technologies, and combinations of technologies that meet the business
needs of their customers while complying with this program.
    To minimize complexity, a single van is used to represent each box
van trailer subcategory in compliance and in our feasibility analysis.
Within the short box dry and refrigerated van subcategories (50-foot
and shorter), the largest fraction of those trailers are 28 feet in
length. Similarly, 53-foot vans make up the majority of the long box
dry and refrigerated vans. Consequently, a 28-foot dry van is used to
represent all lengths of short dry vans and a 53-foot dry van
represents all lengths of long dry vans in this analysis and for
compliance. Similar lengths represent the short and long refrigerated
van subcategories. This means that manufacturers do not need to analyze
the performance of devices for each trailer length in each subcategory.
This approach provides a conservative estimate of CO2
emissions and fuel consumption reductions for the longer vans within a
given length subcategory,\350\ but the agencies believe that the need
to avoid an overly complex compliance program, reinforced by most of
the industry comments, justifies this approach.
---------------------------------------------------------------------------

    \350\ For example, aerodynamic devices on a 48 foot box van will
perform somewhat better than on a 28 foot box van, so our analysis
likely underestimates the benefits of these technologies. See
Chapter <IP_ADDRESS>.2.6 of the RIA and Memorandum to Docket EPA-HQ-OAR-
2014-0827. ''
---------------------------------------------------------------------------

(a) Aerodynamic Technologies
    For box vans under these rules, aerodynamic performance of tractor-
trailers is evaluated using a vehicle's aerodynamic drag area,
CdA. However, unlike the tractor program, the performance of
trailer technologies is quantified using changes in CdA (or
``delta CdA'') rather than absolute values. This delta
CdA classification methodology, which measures improvement
in performance relative to a baseline, is similar to the SmartWay
technology verification program with which most long box van
manufacturers are already familiar. The one difference is that,
although EPA's SmartWay aerodynamic verification program uses a
relative improvement, the metric is a percent fuel savings, whereas the
compliance program for Phase 2 uses change in drag area, delta
CdA. Chapter <IP_ADDRESS>.1 of the RIA provides a comparison of
the SmartWay and Phase 2 metrics.
    The agencies proposed to use a delta CdA measured at
zero-yaw (head-on wind) in the trailer aerodynamic test procedures (80
FR 40277). However, comments from several stakeholders including ACEEE,
CARB, ICCT, RMA, STEMCO, and Utility suggested that measurements that
account for cross-wind provide a more appropriate measure of the
benefits these technologies would experience in the real world,
especially for technologies that are effective when the wind is at an
angle. The agencies evaluated our own aerodynamic test data, including
data collected to justify use of wind-average results in the proposed
tractor program, and we recognize that the drag coefficient increases
under cross-wind conditions likely seen in real-world operation. Since
wind-averaging will account for this, and more appropriately capture
aerodynamic benefits from many devices, including several small-scale
devices, we are adopting a wind-averaged approach for aerodynamic
testing in the trailer program. See Section IV.E.(3)(b)(ii) below and
Chapter <IP_ADDRESS>.2 of the RIA for a summary of yaw-angle effect as
observed in our aerodynamic testing. The feasibility analysis that
follows was performed using wind-averaged delta CdA values.
(i) Aerodynamic Technologies for Non-Box Trailers
    The agencies are aware that some side skirts have been adapted for
the non-box trailers considered in this rule (e.g., tank trailers,
flatbeds, and container chassis). CARB submitted comments noting that
some of these technologies have shown potential for large reductions in
drag. At this time, however, we are unable to sufficiently assess the
degree of CO2 and fuel consumption improvement that could
generally be achieved across this segment of the industry and the
associated costs of these technologies. In the case of each of the
general non-box trailer types included in the trailer program, the
range of physical trailer designs, including the areas where
aerodynamic devices would be installed, is great, and technologies to
date tend to be designed for narrow applications. This lack of basic
information about the applicability of future technologies for these
trailer types also inhibits our ability to estimate costs, either of
the specific future designs themselves or of the size of the market for
any particular product. As a result, we expect that standards
predicated on aerodynamic technologies for these trailer types could
result in relatively little emission and fuel consumption improvement
at relatively high costs. We will continue to monitor this segment of
the trailer industry in this regard and may consider further action in
the future.
    The agencies proposed to adopt design-based tire standards (i.e.

standards not predicated on any aerodynamic technology, and for which
neither GEM nor the GEM-based equation is required) for these trailers
to eliminate the need for performance testing and to reduce the overall
compliance burden for these manufacturers. 80 FR 40257. The data
submitted and adoption rates suggested by CARB would not provide a
large enough reduction in CO2 and fuel consumption from non-
box trailer aerodynamics to justify the increased burden on these
manufacturers. In addition, we believe that there is not currently
sufficient information to develop aerodynamic performance standards on
these relatively new and untried technologies. Consequently, we are
adopting design-based tire technology standards for non-box trailers,
as proposed. Non-box trailer manufacturers may include aerodynamic
improvements in their future trailer designs, but non-box trailer
aerodynamic devices cannot be used for compliance at any point in the
Phase 2 program.
(ii) Aerodynamic Technologies for Box Vans
    EPA collected aerodynamic test data for several tractor-trailer
configurations equipped with technologies similar to common SmartWay-
verified technologies. As mentioned previously, SmartWay-verified
technologies are evaluated on 53-foot dry vans. However, the
CO2- and fuel consumption-reducing potential of some
aerodynamic technologies demonstrated on 53-foot dry vans can be
translated to refrigerated vans and box trailers of other lengths. Some
fleets have opted to add trailer skirts to their refrigerated vans and
28-foot trailers and our testing included dry vans of length 53-foot,
48-foot, 33-foot, and 28-foot.\351\
---------------------------------------------------------------------------

    \351\ Although, as noted above, compliance testing (where
required) uses either a 28 foot van or 53 foot van to simplify the
compliance process.
---------------------------------------------------------------------------

    In order to evaluate performance and cost of the aerodynamic
technologies, the agencies identified ``packages'' of individual or
combined technologies that are being sold today on box trailers. The
agencies also identified distinct performance levels (i.e., bins) for
these technology packages based on EPA's aerodynamic testing. All
technology packages that produce similar improvements in drag would be
categorized as meeting the same bin level of performance. The agencies
recognize that there are other technology options that have similar
performance to those that we analyzed. We chose the technologies
presented here based on their current adoption rates and availability
of test data.
    The agencies are adopting a regulatory structure for box trailers
with seven bins to evaluate aerodynamic performance. Note that these
bins are slightly different than those proposed. We adjusted the
aerodynamic bins to reflect additional data and the use of wind-
averaged results. The most notable difference is that we expanded the
width of the lower bins. The NPRM Bins III, IV and V were reduced to
two bins. Bins V, VI, and VII are identical to the highest bins from
the NPRM (NPRM bins VI, VII, and VIII). See Chapter <IP_ADDRESS>.3 of the
RIA for a complete description of the development of these bins.
    In the final trailer program, Bin I represents a base trailer with
no aerodynamic technologies added and a delta CdA of zero.
Bin II is intended to capture aerodynamic devices that achieve small
reductions in CO2 and fuel consumption. Some gap reducers
may achieve Bin II on long dry vans, and most individual devices (e.g.,
skirts or tails) will achieve this bin for short box vans. We expect a
majority of single aerodynamic devices to perform in the range of Bins
III through IV for long box vans. Combinations of devices are expected
to meet Bin III for short vans and Bin V or Bin VI levels of
performance for long vans. Bin VI represents the more optimized
combinations of technologies on long vans. The agencies observed one
device combination that met Bin VI in our aerodynamic testing and did
not observe any combinations that meet Bin VII. This final level is
designed to represent aerodynamic improvements that may become
available in the future, including aerodynamic devices yet to be
designed or approaches that incorporate changes to the design of
trailer bodies. The agencies believe there is ample lead time to
optimize additional existing Bin V combinations such that they can also
meet Bin VI by MY 2027. However, none of the standards are predicated
on the performance of Bin VII aerodynamic improvements. See Table IV-14
and accompanying text.
    Table IV-5 illustrates the bin structure that the agencies are
adopting as the basis for box vans to demonstrate compliance. The
agencies believe these bins apply to all box vans (dry and refrigerated
vans of various lengths). Although the underlying test data from EPA's
aerodynamic testing program reflect some variation due to differences
in test methods, as well as differences in trailer and aerodynamic
device models, the agencies believe that each of these bins covers a
wide enough range of delta CdAs to account for the
uncertainty. See RIA Chapter 2.10 for more information.
    When manufacturers obtain test results, they would check the range
shown in Table IV-5 for the measured CdA value and use the
corresponding input value for compliance. Note that these are wind-
averaged results, as described in Chapter 2.10 of the RIA and below in
Section IV.E.(3)(b)(ii). Also, the input is a threshold and not an
average of the bin range. Consequently, the compliance results will be
a conservative estimate of the performance of most technologies that
achieve a given bin.\352\
---------------------------------------------------------------------------

    \352\ This is in contrast to the tractor program where
manufacturers obtain absolute CdA values in tractor
aerodynamic testing. The tractor results are corrected to coastdown
values before applying them to bins and obtaining a bin-average
value as a compliance input. Trailers measure a delta CdA
and do not have a correction to a reference method (see Section
IV.E.(3)(b)). The lower threshold approach adopted for the trailer
compliance inputs limits the chance of over-predicting performance
when a reference method correction is not applied.

 Table IV-5--Technology Bins Used To Evaluate Trailer Benefits and Costs
------------------------------------------------------------------------
                                                 Delta CdA
                                 ---------------------------------------
               Bin                                          Input value
                                      Measured value      for compliance
------------------------------------------------------------------------
Bin I...........................  <0.10.................             0.0
Bin II..........................  0.10-0.39.............             0.1
Bin III.........................  0.40-0.69.............             0.4
Bin IV..........................  0.70-0.99.............             0.7
Bin V...........................  1.00-1.39.............             1.0
Bin VI..........................  1.4-1.79..............             1.4
Bin VII.........................  >=1.80................             1.8
------------------------------------------------------------------------

    To develop the standards for box trailers, the agencies assessed
the CO2 emissions and fuel consumption impacts of the
aerodynamic bins using an equation based on the GEM vehicle simulation
tool. See Section II and Section IV.E. (1) for more information about
GEM and Chapter 2.10.5 of the RIA for our development of the GEM-based
equation. Within GEM, and reflected in the results of the equation, the
aerodynamic performance of each box van subcategory is evaluated by
subtracting the delta CdA shown in Table IV-5 from the
CdA value representing a specific standard tractor pulling a
trailer with no CO2- or fuel consumption-reducing
technologies (i.e., a ``no-control'' trailer). In other words, the
tractor-trailer is simulated with improvements to the baseline trailer.
The agencies chose to model the no-control long box dry van using a
CdA value of 6.0 m\2\ (the mean wind-averaged CdA
from EPA's wind tunnel

testing). The single, short box dry vans showed lower CdA
values compared to its 53-foot counterpart in EPA's wind tunnel testing
with an average of 5.6 m\2\. The agencies did not test any refrigerated
vans, but we assumed a refrigerated van's TRU would behave similar to a
gap reducer. Our test results in Chapter <IP_ADDRESS>.3 did not show gap
reducer technologies to have a significant effect on CdA and
the agencies accordingly assigned the same default CdA to
refrigerated and dry box vans in GEM. Note that the trailer
subcategories that have design standards (i.e., non-box and non-aero
box trailers) do not have numerical standards to meet, and do not have
defaults in GEM. Table IV-6 illustrates the no-control drag areas
(CdA) associated with each trailer subcategory.

 Table IV-6--Default Aerodynamic Drag Area (CdA) Values Associated With
                Each (No-Control) Trailer Modeled in GEM
------------------------------------------------------------------------
                   Trailer subcategory                      CdA (M\2\)
------------------------------------------------------------------------
Long Dry Van............................................             6.0
Short Dry Van...........................................             5.6
Long Ref. Van...........................................             6.0
Short Ref. Van..........................................             5.6
------------------------------------------------------------------------

    Current ``boat tail'' devices, applied to the rear of a trailer
with rear swing doors, are typically designed to collapse flat as the
trailer rear doors are opened. If the tail structure can remain in the
collapsed configuration when the doors are closed, the benefit of the
device is lost. We requested comment on whether we should require that
trailer manufacturers using such devices for compliance with these
standards only use designs that automatically deploy when the vehicle
is in motion. STEMCO commented that automatic deployment should not be
required, since those systems are more expensive, and in their view,
not necessary for the Phase 2 program. STEMCO believes that, since
there is a strong economic incentive for operators to ensure that the
devices are correctly deployed in order to achieve the greatest fuel
cost payback, a regulatory requirement related to deployment is not
needed. We generally agree, and have not included such a requirement in
the final trailer program. For this analysis, we consider all boat
tails to be properly deployed.
    The agencies are aware that physical characteristics of some box
trailers influence the technologies that can be applied. For instance,
the TRUs on refrigerated vans are located at the front of the trailer,
which prevents the use of current gap-reducers, either by occupying the
space that a front-end fairing would use, or by blocking air flow that
the TRU needs for cooling purposes. Similarly, drop deck dry vans have
lowered floors between the landing gear and the trailer axles that
limit the ability to use side skirts. We discuss another example, roll-
up rear doors, in Section IV.C.(1)(a) above. The agencies considered
the availability and limitations of aerodynamic technologies for each
trailer type evaluated in our feasibility analysis of the standards.
(b) Tire Rolling Resistance
    Similar to the Phase 2 tractor and vocational vehicle programs, the
agencies are adopting standards based on adoption of lower rolling
resistance tires. While some box vans continue to be sold with tires of
higher rolling resistances, the agencies believe most box van tires
currently achieve a tire CRR of 6.0 kg/ton or better.
Feedback from several box trailer manufacturers indicates that the
standard tires offered on their new trailers are SmartWay-verified
tires (i.e., CRR of 5.1 kg/ton or better). An informal
survey of members from the Truck Trailer Manufacturers Association
(TTMA) in 2014 indicates about 85 percent of box vans sold at that time
had SmartWay tires.\353\
---------------------------------------------------------------------------

    \353\ Letter, Truck Trailer Manufacturers Association to EPA.
Received on October 16, 2014. Docket EPA-HQ-OAR-2014-0827-0146.
---------------------------------------------------------------------------

    The agencies evaluated two levels of tire performance for box vans
beyond the baseline trailer tire rolling resistance level (TRRL) of 6.0
kg/ton. The first performance level was set at the criteria for
SmartWay-verification for trailer tires, 5.1 kg/ton, which is a 15
percent reduction in CRR from the baseline. As mentioned
previously, several tire models available today achieve rolling
resistance values well below the present SmartWay threshold. Given the
multiple year phase-in of the standards, the agencies expect that tire
manufacturers will continue to respond to demand for more efficient
tires and will offer increasing numbers of tire models with rolling
resistance values significantly better than today's typical LRR tires.
In this context, we believe it is reasonable to expect a large fraction
of the trailer industry could adopt tires with rolling resistances at a
second performance level that will achieve an additional reduction in
rolling resistance, especially in the later stages of the program. The
agencies project the CRR for this second level of
performance to be a value of 4.7 kg/ton (a 22 percent reduction from
the baseline tire).
    The vast majority of box van miles occur on-road, and current LRR
tire designs are appropriate and effective for those applications. We
note that current designs of LRR tires may not be appropriate for some
non-box trailer types, including those that operate significantly in
off-road conditions. We expect that the tire manufacturing industry
will continue to expand their offerings of tire designs to additional
applications. Regardless, by limiting the non-box trailer types covered
by the final trailer program to those generally used in on-highway
applications (tanks, flatbeds, and container chassis), the program
avoids most of these potential situations.
    We received comment from Michelin supporting the use of 6.0 kg/ton
as the box trailer tire rolling resistance baseline, but they expressed
concern that the SmartWay threshold of 5.1 kg/ton does not apply for
non-box trailers, and could compromise their operation. Similarly, the
Rubber Manufacturers Association indicated that a baseline of 6.0 kg/
ton does not apply to non-box trailers. The agencies agree that the
baseline tires for non-box trailers should have a higher rolling
resistance, but we did not receive any comments that included
CRR data. For the analysis for the final rules, the agencies
revised the baseline CRR to a value of 6.5 kg/ton for non-
box trailer manufacturers. The updated non-box trailer designs
standards require LRR tires of 6.0 kg/ton in the first stage of the
program and 5.1 kg/ton in the later years. Nowhere in the final program
do we require Level 4 tires for non-box trailers.
    The agencies evaluated four tire rolling resistance levels,
summarized in Table IV-7, in the feasibility analysis of the following
sections. It should be noted that these levels are targets for setting
the stringency of the box van performance standards and rolling
resistance thresholds for the non-box design standards. For compliance,
box van manufacturers have the option to use tires with any rolling
resistance and are not be limited to these TRRLs.

 Table IV-7--Summary of Trailer Tire Rolling Resistance Levels Evaluated
------------------------------------------------------------------------
                                                           CRR (kg/ton)
              Tire rolling resistance level
------------------------------------------------------------------------
Level 1 (Non-Box Baseline)..............................             6.5
Level 2 (Box Van Baseline ).............................             6.0
Level 3.................................................             5.1
Level 4.................................................             4.7
------------------------------------------------------------------------

(c) Tire Pressure Systems
    Tire pressure monitoring systems (TPMS) and automatic tire
inflation systems (ATIS) are designed to address under-inflated tires.
Both systems alert

drivers if a tire's pressure drops below its set point. TPMS are
simpler and merely monitor tire pressure. Thus, they require user-
interaction to reinflate to the appropriate pressure. Today's ATIS, on
the other hand, typically take advantage of trailers' air brake systems
to supply air back into the tires (continuously or on demand) until a
selected pressure is achieved. In the event of a slow leak, ATIS have
the added benefit of maintaining enough pressure to allow the driver to
get to a safe stopping area. See Chapter <IP_ADDRESS> of the RIA for more
on tire pressure systems.
    The agencies proposed that ATIS be the only tire pressure system
allowed to be used to meet the standards, since TPMS require action on
the part of the operator. Our position at the time of the proposal was
that TPMS could not sufficiently guarantee proper inflation. 80 FR
40262. However, some commenters stated that TPMS are effective in
encouraging proper tire pressure maintenance, and should also be
eligible as a compliance option. Commenters did not provide specific
data about the overall effectiveness of TPMS. However, we are aware of
the emergence of TPMS that use telematics to automatically report tire
pressure data to a central contact. It is also our understanding that
there is a growing recognition among fleet and individual operators of
the potential value that these systems can provide to operators, so
long as the operator and/or a central fleet contact take action to
address cases of low tire pressures indicated by the systems. These
factors have led the agencies to reconsider our approach to TPMS. As
described in Section IV.B. above, we now believe that TPMS provides
overall fuel consumption and CO2 reductions, and the final
program recognizes the option of TPMS as part of the compliance path
for all covered trailers.
    NHTSA and EPA recognize the role of proper tire inflation in
maintaining optimum tire rolling resistance during normal trailer
operation. Rather than require performance testing of tire pressure
systems, the agencies recognize the benefits of these systems, and the
program applies default reduction values for manufacturers that
incorporate ATIS or TPMS into their trailer designs. Based on
information available today, we believe that most tire pressure
technologies and systems in typical use perform similarly.
    We proposed to assign a 1.5 percent reduction in CO2 and
fuel consumption for all trailers that implement ATIS, based on
information available at that time.\354\ We did not receive any
comments directly addressing the proposed reduction value. However, the
agencies believed it was appropriate to align the effectiveness of tire
pressure systems for tractors, trailers and vocational vehicles, and
the agencies are adopting a 1.2 percent reduction for ATIS for each of
these vehicle categories. As just noted, we are also adopting
provisions that recognize a CO2 and fuel consumption
reduction for TPMS. The agencies believe that sufficient incentive
exists for truck operators to address low tire pressure conditions if
they are notified that they exist through a TPMS (for example, for
reasons of personal safety as well as fuel savings). However, we
recognize the dependence on operator action for TPMS, and we are
adopting a reduction of 1.0 percent for these systems. We have
concluded that the use of these systems can consistently ensure that
tire pressure and tire rolling resistance are maintained. Sections
III.D.(1)(b) and V.C.(1)(a) also discuss the overall Phase 2 program's
treatment of both types of tire pressure systems for tractors and
vocational vehicles, respectively.
---------------------------------------------------------------------------

    \354\ See Chapter <IP_ADDRESS> of the RIA.
---------------------------------------------------------------------------

    We selected the standards for most box vans with the expectation
that a high rate of adoption of ATIS will occur during all years of the
phase-in of the program, and that manufacturers of non-aero vans, and
non-box trailers will install either TPMS or ATIS, as well as LRR
tires, to comply with the design-based tire standards.
    In the performance-based compliance approach to full- and partial-
aero box vans, the program incorporates a small discount in the value
of TPMS in the compliance equation as compared to ATIS, to reflect the
inherent user interaction required for TPMS to be effective. In the
design-based compliance approach for non-aero vans and non-box
trailers, manufacturers may comply by using either TPMS or ATIS, which
in that case are valued equally. See Section IV.D.(2)(d) below for
discussion of our estimates of the degree of adoption of tire pressure
systems prior to and at various points in the phase-in of the proposed
program.
(d) Weight Reduction
    As proposed, the trailer program provides manufacturers the option
of complying through the substitution of specified lighter-weight
components that can be clearly isolated from the trailer as a whole. In
the proposal, the agencies identified several conventional components
with lighter-weight substitutes that are currently available (e.g.,
substituting conventional dual tires mounted on steel wheels with wide-
based single tires mounted on aluminum wheels). 80 FR 40262. Several
commenters provided additional component suggestions, with information
about their typical associated weight reductions. The component
substitutions we have included in the final program, and the weight
savings that we are associating with each component, are presented in
the RIA Chapter <IP_ADDRESS> and 40 CFR 1037.515. The agencies have
identified 12 common trailer components for which lighter weight
options are currently available (see 40 CFR
1037.515).355 356 357 358 Manufacturers that adopt these
technologies and choose to use them as part of their compliance
strategy sum the associated weight reductions and apply those values in
the GEM-based compliance equation (see Section IV.E.(2)(a)). We believe
that the initial cost of these component substitutions is currently
substantial enough that only a relatively small segment of the industry
has adopted these technologies today.
---------------------------------------------------------------------------

    \355\ Scarcelli, Jamie. ``Fuel Efficiency for Trailers''
Presented at ACEEE/ICCT Workshop: Emerging Technologies for Heavy-
Duty Vehicle Fuel Efficiency, Wabash National Corporation. July 22,
2014.
    \356\ ``Weight Reduction: A Glance at Clean Freight
Strategies,'' EPA SmartWay. EPA420F09-043. Available at: http://permanent.access.gpo.gov/gpo38937/EPA420F09-043.pdf.
    \357\ Memorandum dated June 2015 regarding confidential weight
reduction information obtained during SBREFA Panel. Docket EPA-HQ-
OAR-2014-0827.
    \358\ Randall Scheps, Aluminum Association, ``The Aluminum
Advantage: Exploring Commercial Vehicles Applications,'' presented
in Ann Arbor, Michigan, June 18, 2009.
---------------------------------------------------------------------------

    There is no clear ``baseline'' for current trailer weight against
which lower-weight designs could be compared for regulatory purposes.
For this reason, the agencies do not believe it is appropriate or fair
across the industry to apply overall weight reductions toward
compliance using a universal baseline trailer. However, the agencies do
believe it is appropriate to give a manufacturer credit for overall
weight reduction achieved in their own product line. In the final
program, we are clarifying that manufacturers of box trailers with
significant weight reductions have the option of using our off-cycle
credit process to compare overall weight reduction of future trailers
using an appropriate baseline from their own production. This process
allows manufacturers to do a comparison of their new trailer to a
previous model to quantify the weight reduction improvements.
Manufacturers wishing to go this route should contact

EPA in advance to discuss appropriate test procedures. More information
about the off-cycle process can be found in Section IV.E.(5)(d) and in
40 CFR 1037.610 or 49 CFR 535.7. Note that non-box trailers and non-
aero box vans have design standards that are limited to adoption of
lower rolling resistance tires and tire pressure systems, and do not
include weight reduction as part of their simplified compliance
demonstration.
    The agencies recognize that when weight reduction is applied to a
trailer, some operators will replace that saved weight with additional
payload. To account for this in the average vehicle represented by
EPA's GEM vehicle simulation tool, it is assumed that one-third of any
weight reduction will be applied to the payload. Wabash suggested that
the agencies reconsider the distribution of weight between payload and
trailer weight when modeling weight reduction, expressing concern that
the reduction was not receiving appropriate credit in the program.
Although the simulated vehicle in GEM only receives \2/3\ of the weight
reduction applied, the model calculates CO2 emissions and
fuel consumption on a per-ton-mile basis by dividing by the payload,
which now includes the extra one-third from weight reduction. Dividing
by a larger payload results in lower CO2 and fuel
consumption values.\359\
---------------------------------------------------------------------------

    \359\ Memorandum to Docket EPA-HQ-OAR-2014-0827, ``Evaluation of
Weight Reduction Distribution in Response to Public Comments from
Wabash National Corporation,'' June 18, 2016.
---------------------------------------------------------------------------

    For 53-foot vans simulated in GEM (and thus, for the GEM-based
equation), it takes a weight reduction of nearly 1,000 pounds before a
one percent fuel savings is achieved. The impact of the same 1000
pounds is slightly greater for shorter vans, due to their lower overall
weight, but the effectiveness of weight reduction is still relatively
low compared to the effectiveness of many aerodynamic technologies. In
addition, large material substitutions can be costly. The agencies thus
believe that few trailer manufacturers will apply weight reduction
solely as a means of achieving reduced fuel consumption and
CO2 emissions. Therefore, we are adopting standards that
could be met without reducing weight--that is, the feasible compliance
path set out by the agencies for this program does not assume weight
reduction as a compliance avenue. However, as discussed here, the final
program includes the option for box trailer manufacturers to apply
weight reduction to some of their trailers as part of their compliance
strategy.
(2) Effectiveness, Adoption Rates, and Costs of Technologies for the
Trailer Standards
    The agencies evaluated the technologies above as they apply to each
of the trailer subcategories. The next sections describe the
effectiveness, adoption rates and costs associated with these
technologies. The effectiveness and adoption rate projections were used
to derive these standards.
(a) No-Control Default Tractor-Trailer Vehicles in GEM (Box Van
Standards Only)
    The regulatory purpose of EPA's heavy-duty vehicle compliance tool,
GEM, is to combine the effects of trailer technologies through
simulation so that they can be expressed as g/ton-mile and gal/1000
ton-mile and thus avoid the need for direct testing of each trailer
being certified. All of the standards for box vans (with the exception
of non-aero box vans, which have design standards) use an equation
derived from GEM to demonstrate compliance. The trailer program has
separate performance standards for each box van subcategory (again,
with the exception of non-aero box vans) and each of these
subcategories is modeled as a tractor-trailer combination that we
believe reflects the average physical characteristics and use pattern
of vans in that subcategory. Long vans are pulled by sleeper cab
tractors and use the long-haul drive cycle weightings. Short vans are
pulled by day cabs and have the short-haul drive cycle weightings.
Short vans also have a lighter payload and overall vehicle weight
compared to their longer counterparts.
    Table IV-8 highlights the relevant vehicle characteristics for the
no-control default of each subcategory (i.e., zero CO2- or
fuel consumption reducing technologies installed). Baseline trailer
tires are used, and the drag area, which is a function of the
aerodynamic characteristics of both the tractor and trailer, is set to
the values shown previously in Table IV-6. Weight reduction and tire
pressure systems are not applied in these default vehicles. Chapter
2.10 of the RIA provides a detailed description of the development of
these default tractor-trailers. Note that the agencies proposed to use
Class 8 tractors for all default tractor-trailer vehicles. However, we
are adopting the final standards based on 4x2 Class 7 tractors for
short box vans.

              Table IV-8--Characteristics of the No-Control Default Tractor-Trailer Vehicles in GEM
----------------------------------------------------------------------------------------------------------------
                                                  Dry van                            Refrigerated van
----------------------------------------------------------------------------------------------------------------
         Trailer length                  Long                Short               Long                Short
----------------------------------------------------------------------------------------------------------------
Standard Tractor:
    Class.......................  Class 8...........  Class 7...........  Class 8...........  Class 7.
    Cab Type....................  Sleeper...........  Day...............  Sleeper...........  Day.
    Roof Height.................  High..............  High..............  High..............  High.
    Axle Configuration..........  6 x 4.............  4 x 2.............  6 x 4.............  4 x 2.
    Engine......................  2018 MY 15L, 455    2018 MY 11L, 350    2018 MY 15L, 455    2018 MY 11L, 350
                                   HP.                 HP.                 HP.                 HP.
    Steer Tire RR (kg/ton)......  6.54..............  6.54..............  6.54..............  6.54.
    Drive Tire RR (kg/ton)......  6.92..............  6.92..............  6.92..............  6.92.
    Drag Area, CdA (m\2\).......  6.0...............  5.6...............  6.0...............  5.6.
    Number of Trailer Axles.....  2.................  1.................  2.................  1.
    Trailer Tire RR (kg/ton)....  6.00..............  6.00..............  6.00..............  6.00.
    Total Weight (kg)...........  31978.............  18306.............  33778.............  20106.
    Payload (tons)..............  19................  10................  19................  10.
    Tire Pressure System Use....  0.................  0.................  0.................  0.
    Weight Reduction (lb).......  0.................  0.................  0.................  0.
Drive Cycle Weightings:
    65-MPH Cruise...............  86%...............  64%...............  86%...............  64%.
    55-MPH Cruise...............  9%................  17%...............  9%................  17%.

    Transient Driving...........  5%................  19%...............  5%................  19%.
----------------------------------------------------------------------------------------------------------------

(b) Effectiveness of Technologies
    As already noted, the agencies recognize trailer improvements via
four performance parameters: Aerodynamic drag reduction, tire rolling
resistance reduction, the adoption of tire pressure systems, and
weight-reducing strategies. Table IV-9 summarizes the performance
levels the agencies evaluated for each of these parameters based on the
technology characteristics outlined in Section IV.D.(1).

       Table IV-9--Performance Parameters for the Trailer Program
------------------------------------------------------------------------

------------------------------------------------------------------------
Aerodynamics (Delta CdA, m\2\):
    Bin I..............................  0.0.
    Bin II.............................  0.1.
    Bin III............................  0.4.
    Bin IV.............................  0.7.
    Bin V..............................  1.0.
    Bin VI.............................  1.4.
    Bin VII............................  1.8.
Tire Rolling Resistance (CRR, kg/ton):
    Tire Level 1.......................  6.5.
    Tire Level 2.......................  6.0.
    Tire Level 3.......................  5.1.
    Tire Level 4.......................  4.7.
Tire Inflation System (% reduction):
    ATIS...............................  1.2.
    TPMS...............................  1.0.
Weight Reduction (lb):
    Weight.............................  1/3 added to payload, remaining
                                          reduces overall vehicle
                                          weight.
------------------------------------------------------------------------

    These performance parameters have different effects on each trailer
subcategory due to differences in the simulated trailer
characteristics. Table IV-10 shows the agencies' estimates of the
effectiveness of each parameter for the four box van types. Each
technology was evaluated using the baseline parameter values for the
other technology categories. For example, each aerodynamic bin was
evaluated using the baseline tire (6.0 kg/ton) and the baseline weight
reduction option (zero pounds). The table shows that aerodynamic
improvements offer the largest potential for CO2 emissions
and fuel consumption reductions, making them relatively effective
technologies.

            Table IV-10--Effectiveness (Percent CO[ihel2] Emissions and Fuel Consumption) of Technologies for Box Vans in the Trailer Program
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Dry van                    Refrigerated van
                       Aerodynamics                               Delta CdA (m\2\)       ---------------------------------------------------------------
                                                                                Long  (%)      Short  (%)       Long  (%)      Short  (%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bin I.....................................................                           0.0               0               0               0               0
Bin II....................................................                           0.1               1               1               1               1
Bin III...................................................                           0.4               3               3               3               3
Bin IV....................................................                           0.7               5               5               5               5
Bin V.....................................................                           1.0               7               7               7               7
Bin VI....................................................                           1.4               9              10               9              10
Bin VII...................................................                           1.8              12              13              12              13
--------------------------------------------------------------------------------------------------------------------------------------------------------
                  Tire Rolling Resistance                           CRR (kg/ton)                      Dry van
                                                                          Refrigerated van
                                                                                ---------------------------------------------------------------
                                                                                Long            Short           Long            Short
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level 1...................................................                           6.5  ..............  ..............  ..............  ..............
Level 2...................................................                           6.0               0               0               0               0
Level 3...................................................                           5.1              -2              -1              -2              -1
Level 4...................................................                           4.7              -3              -2              -3              -2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                     Weight Reduction                                Weight (lb)                      Dry van
                                                                          Refrigerated van
                                                                                ---------------------------------------------------------------
                                                                                Long            Short           Long            Short
--------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline..................................................                             0               0               0               0               0

Option 1..................................................                           100               0               0               0               0
Option 2..................................................                           500               1               1               1               1
Option 3..................................................                          1000               1               2               1               2
Option 4..................................................                          2000               2               4               2               4
--------------------------------------------------------------------------------------------------------------------------------------------------------

(c) Baseline Tractor-Trailer To Evaluate Benefits and Costs
    In order to evaluate the benefits and costs of the final standards
for each of the ten subcategories, it is necessary to establish a
reference point for comparison. As mentioned previously, the
technologies described in Section IV.D.(1) exist in the market today,
and their adoption is driven by available fuel savings as well as by
the voluntary SmartWay Partnership and California's tractor-trailer
requirements. For these rules, the agencies identified baseline
tractor-trailers for each trailer subcategory based on the technology
adoption rates we project would exist in MY 2018 if this trailer
program was not implemented.
    CARB's comments noted the informal survey of TTMA members provided
in letter from TTMA to EPA in 2014 regarding current adoption rates of
several technologies. CARB suggested that our proposed baseline
adoption rates did not reflect the data in that letter.\360\ We have
reassessed available data and we believe that higher baseline rates are
more appropriate, and have made corresponding changes in our analysis.
First, we created a separate baseline for box vans that qualify as
full-aero, box vans that qualify as partial-aero, and box vans that
qualify as non-aero. Because of the challenges of installing effective
aerodynamic devices, market forces are not likely to significantly
drive adoption of CO2- and fuel-consumption reducing
technologies for trailers with work performing equipment (e.g., lift
gates), and we are projecting zero adoption of the technologies in the
baselines for partial- and non-aero box vans before the start of this
program. Similarly, we assume that there will be zero adoption of these
technologies for non-box trailers in the baseline. We updated the
baseline tire rolling resistance level for non-box trailers to reflect
the lower 6.5 kg/ton value in response to RMA's comment that these
trailers have different operational characteristics and should not have
the same baseline tires as box vans (see Section IV.D.(1)(b) above).
---------------------------------------------------------------------------

    \360\ Letter, Truck Trailer Manufacturers Association to EPA.
Received on October 16, 2014. Docket EPA-HQ-OAR-2014-0827-0146.
---------------------------------------------------------------------------

    TTMA's survey indicated that 35 percent of long vans and less than
2 percent of vans under 53-foot in length include aerodynamic devices,
and over 80 percent have adopted lower rolling resistance tires. The
agencies believe the trailers for which manufacturers have adopted
these technologies are likely to be trailers that would qualify as
``full-aero'' vans, and we adjusted our baselines to reflect these
values. Our baseline assumes that aerodynamics would increase to 40
percent adoption for full-aero long vans (dry and refrigerated) and 5
percent for full-aero short vans by 2018 without the Phase 2 standards.
We also assume adoption of lower rolling resistance tires (Level 1)
will increase to 90 percent and ATIS to 45 percent in the baseline. We
held these adoption rates constant throughout the timeframe of the
rules. Table IV-11 summarizes the updated baseline trailers for each
trailer subcategory.

 Table IV-11--Estimated Adoption Rates and Average Performance Parameters for the Flat Baseline Trailers for MY
                                                 2018 and Later
----------------------------------------------------------------------------------------------------------------
                                                                           All partial-aero,      All non-box
           Technology                  Long vans          Short vans         non-aero vans         trailers
----------------------------------------------------------------------------------------------------------------
Aerodynamics:
    Bin I.......................                 55%                 95%                100%                100%
    Bin II......................  ..................                  5%
    Bin III.....................                 40%
    Bin IV......................                  5%
    Bin V.......................
    Bin VI......................
    Bin VII.....................
        Average Delta CdA (m2)                   0.2                 0.0                 0.0                 0.0
         \a\....................
Tire Rolling Resistance:
    Level 1.....................  ..................  ..................  ..................                100%
    Level 2.....................                 10%                 10%                100%
    Level 3.....................                 90%                 90%
    Level 4.....................
        Average CRR (kg/ton) \a\                 5.2                 5.2                 6.0                 6.5
Tire Pressure Systems:
    ATIS........................                 45%                 30%
    TPMS........................
        Average Pressure System                 0.5%                0.3%                0.0%                0.0%
         Reduction (%) \a\......
Weight Reduction:

        Weight (lb) \b\.........
----------------------------------------------------------------------------------------------------------------
Notes:
A blank cell indicates a zero value.
\a\ Combines adoption rates with performance levels shown in Table IV-9.
\b\ Weight reduction was not projected for the baseline trailers.

    Also shown in Table IV-11 are average aerodynamic performance
(delta CdA), average tire rolling resistance
(CRR), and average reductions due to use of tire pressure
systems and weight reduction for each reference trailer. These values
indicate the performance of theoretical average tractor-trailers that
the agencies project would be in use in 2018 if no federal regulations
were in place for trailer CO2 and fuel consumption. The
average tractor-trailer vehicles serve as baselines for each trailer
subcategory.
    Because the agencies cannot be certain about future trends, we also
considered a second baseline. This dynamic baseline reflects the
possibility that, absent a Phase 2 regulation, there would be
continuing adoption of aerodynamic technologies in the long box trailer
market after 2018 that reduce fuel consumption and CO2
emissions. This case assumes the research funded and conducted by the
federal government, industry, academia and other organizations would,
after 2018, result in the adoption of additional aerodynamic
technologies beyond the levels required to comply with existing
regulatory and voluntary programs. One example of such research is the
Department of Energy SuperTruck program which has a goal of
demonstrating cost-effective measures to improve the efficiency of
Class 8 long-haul freight trucks by 50 percent by 2015.\361\ This
baseline assumes that by 2040, 75 percent of new full-aero long vans
would be equipped with SmartWay-verified aerodynamic devices. The
agencies project that the lower rolling resistance tires and ATIS
adoption would remain constant. Table IV-12 shows the agencies'
projected adoption rates of technologies in the dynamic baseline.
---------------------------------------------------------------------------

    \361\ Daimler Truck North America. SuperTruck Program Vehicle
Project Review. June 19, 2014. Docket EPA-HQ-OAR-2014-0827.

 Table IV-12--Projected Adoption Rates and Average Performance Parameters for the Dynamic Baseline for Long Dry
                                              and Refrigerated Vans
                                [All other trailers are the same as Table IV-11]
----------------------------------------------------------------------------------------------------------------
           Technology                                        Long dry and refrigerated
----------------------------------------------------------------------------------------------------------------
           Model year                  2018            2021            2024            2027            2040
----------------------------------------------------------------------------------------------------------------
Aerodynamics:
    Bin I.......................             55%             50%             45%             40%             20%
    Bin II......................
    Bin III.....................             40%             45%             50%             55%             75%
    Bin IV......................              5%              5%              5%              5%              5%
    Bin V.......................
    Bin VI......................
    Bin VII.....................
        Average Delta CdA (m\2\)             0.2             0.3             0.3             0.3             0.4
         \a\....................
Tire Rolling Resistance:
    Level 1.....................
    Level 2.....................             10%             10%             10%             10%             10%
    Level 3.....................             90%             90%             90%             90%             90%
    Level 4.....................
        Average CRR (kg/ton) \a\             5.2             5.2             5.2             5.2             5.2
Tire Pressure Systems:
    ATIS........................             45%             45%             45%             45%             45%
    TPMS........................
        Average Pressure System             0.5%            0.5%            0.5%            0.5%            0.5%
         Reduction (%) \a\......
Weight Reduction (lbs):
        Weight \b\..............
----------------------------------------------------------------------------------------------------------------
Notes:
A blank cell indicates a zero value.
\a\ Combines adoption rates with performance levels shown in Table IV-9.
\b\ Weight reduction was not projected for the baseline trailers.

    The agencies applied the vehicle attributes from Table IV-8 and the
average performance values from Table IV-11 in the Phase 2 GEM vehicle
simulation to calculate the CO2 emissions and fuel
consumption performance of the baseline tractor-trailers. The results
of these simulations are shown in Table IV-13. We used

these CO2 and fuel consumption values to calculate the
relative improvements that will occur over time with a regulatory
program. Note that the large difference between the per ton-mile values
for long and short trailers is due primarily to the large difference in
assumed payload (19 tons compared to 10 tons) and the small difference
between dry and refrigerated vans of the same length are due to
differences in vehicle weight because of the 1800 pounds added to the
simulated refrigerated vans to account for the TRU (see the vehicle
characteristics of the simulated tractor-trailers Table IV-8). The
alternative baseline shown in Table IV-12 mainly impacts the long-term
projections of benefits beyond 2027, which are analyzed in Chapters 5-7
of the RIA.

                             Table IV-13--CO[ihel2] Emissions and Fuel Consumption Results for the Baseline Tractor-Trailers
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Full-aero  dry van         Full-aero         Partial-aero  dry       Partial-aero
---------------------------------------------------------------------------------------   refrigerated van             van            refrigerated van
                                                                                -----------------------------------------------------------------
                             Length                                  Long      Short       Long      Short       Long      Short       Long      Short
--------------------------------------------------------------------------------------------------------------------------------------------------------
CO[ihel2] Emissions (g/ton-mile)................................       83.2      126.5       84.9      130.3       86.1      128.5       87.9      132.4
Fuel Consumption (gal/1000 ton-miles)...........................    8.17289   12.42633    8.33988   12.79961    8.45776   12.62279    8.63458   13.00589
--------------------------------------------------------------------------------------------------------------------------------------------------------

(d) Projected Technology Adoption Rates for the Trailer Standards
    The agencies developed their performance and design standards based
on projected adoption rates of certain technologies. This section
describes how these adoption rates were applied for each of the trailer
subcategories.
(i) Aerodynamic and Tire Technologies for Full- and Partial-Aero Box
Vans
    As described in Section 0, the agencies evaluated several
alternatives for the trailer program. Based on our analysis and
comments received, the agencies are adopting standards consistent with
the agencies' respective statutory authorities. The agencies proposed
alternatives that were based on the use of averaging and the technology
adoption rates for those alternatives at proposal reflected the use of
averaging. As noted in Section IV.B., we received nearly unanimous,
persuasive comments from the trailer industry opposing averaging and
the agencies reconsidered the use of averaging in the early years of
the program. The agencies designed the trailer program to have no
averaging in MY 2018 through MY 2026. In those years, all box vans sold
must meet the standards using any combination of available
technologies. In MY 2027, when the trailer manufacturers are more
comfortable with compliance and the industry is more familiar with the
technologies, trailer manufacturers will have the option to use
averaging to meet the standards. See Section IV.E.(5)(b) below for
additional information about averaging.
    Table IV-14 and Table IV-15 present sets of assumed adoption rates
for aerodynamic, tire, and tire pressure technologies that a
manufacturer could apply to meet the box van standards. Since averaging
would not be allowed for MY 2018-MY 2026, the adoption rates consist of
the combination of a single aerodynamic bin (not reflecting any
averaging of aerodynamic controls), tire rolling resistance level, and
tire pressure system. As mentioned previously, manufacturers can choose
other combinations to meet the standards. Chapter 2.10 of the RIA shows
several examples of alternative compliance pathways.
    The adoption rates in Table IV-14 begin with all full-aero long box
vans achieving current SmartWay-level aerodynamics (Bin III) in MY 2018
with a stepwise progression to achieving Bin V in 2024. The adoption
rates for full-aero short box vans in Table IV-15 assume no adoption of
aerodynamic devices in MY 2018, adoption of single aero devices in MY
2021, and combinations of devices by MY 2024. Although the shorter
lengths of these trailers can restrict the design of aerodynamic
technologies that fully match the SmartWay-like performance levels of
long boxes, we nevertheless expect that trailer and device
manufacturers will continue to innovate skirt, under-body, rear, and
gap-reducing devices and combinations to achieve improved aerodynamic
performance on these shorter trailers.
    The adoption rates in MY 2018-MY 2026 are projected to be 100
percent for each technology, instead of an industry average seen in
other vehicle sectors in the Phase 2 program. Since we are not
considering averaging during those years, each set of adoption rates is
one example of how an individual trailer in each subcategory could
comply. Through MY 2026, the standards are based on technologies that
exist today. We evaluated one technology in our aerodynamic test
programs that met Bin VI levels of performance for long vans,
suggesting that this bin can be met with combinations of existing
aerodynamic technologies, but none of our tested technologies that met
Bin IV levels of performance for short vans. We could not justify
standards based on 100 percent adoption of those levels of performance
as a final step in our progression of stringency. However, the industry
has made great progress toward improving trailer aerodynamics in recent
years and are continuing to optimize these technologies. Although we
are not projecting fundamentally new technologies for trailers, we do
believe aerodynamic performance will evolve in the trailer industry as
a result of this rulemaking. Based on the recent rate of improvement,
the agencies believe that there is ample lead time to optimize
additional existing Bin V and Bin III combinations such that they can
also meet Bins VI and IV by MY 2027 and it is reasonable to project
that more than half of these full-aero capable trailers will have
aerodynamic improvements greater than what is possible with today's
technologies. Our projected aerodynamic improvements in MYs 2027 and
later reflect this performance potential.
    The MY 2027 full-aero box van standards are based on an averaging
program.\362\ We cannot predict what technologies or trailer designs
may be adapted to meet this level of aerodynamic performance, but an
averaging program incentivizes manufacturers to develop advanced
designs with the benefit that not all trailers in their production have
to meet the same level of performance. The gradual increase in assumed
adoption of aerodynamic technologies throughout the phase-in to the MY
2027 standards recognizes that even though many of the technologies are
available today and technologically feasible throughout the phase-in
period, adoption of more advanced technologies will likely take time.
The adoption rates we are

projecting in the interim years and the standards that we developed
from these rates represent steady and reasonable improvement in
aerodynamic performance.
---------------------------------------------------------------------------

    \362\ No averaging is allowed for partial-aero box van reduced
standards, or the design-based standards for non-aero box vans and
non-box trailers.
---------------------------------------------------------------------------

    We expect manufacturers of all box vans will adopt tires such as
SmartWay-verified trailer tires (Level 3) to meet the standards in MY
2018 and will adopt tires with even lower rolling resistance tires
(represented as Level 4) as they become available by MY 2021 and later
years and as fleet experience with these tires develops.
    In establishing standard stringency, the agencies are also assuming
that all box vans will adopt ATIS throughout the program, though
manufacturers have the option to install TPMS if they would prefer to
make up the difference in effectiveness using other technologies. As
mentioned previously, the agencies did not include weight reduction in
their technology adoption projections, but certain types of weight
reduction could be used as part of a compliance pathway, as discussed
in Section IV.D.(1)(d) IV.D.(1)(d) above.

      Table IV-14--Projected Adoption Rates and Average Performance Parameters for Full-Aero Long Box Vans
----------------------------------------------------------------------------------------------------------------
                   Technology                                    Long box dry & refrigerated vans
----------------------------------------------------------------------------------------------------------------
                   Model year                          2018            2021            2024            2027
----------------------------------------------------------------------------------------------------------------
Aerodynamic Technologies:
    Bin I.......................................
    Bin II......................................
    Bin III.....................................            100%
    Bin IV......................................  ..............            100%
    Bin V.......................................  ..............  ..............            100%             30%
    Bin VI......................................  ..............  ..............  ..............             70%
    Bin VII.....................................
        Average Delta CdA (m\2\) \a\............             0.5             0.7             1.0             1.3
Trailer Tire Rolling Resistance:
    Level 1.....................................
    Level 2.....................................  ..............  ..............  ..............              5%
    Level 3.....................................            100%
    Level 4.....................................  ..............            100%            100%             95%
        Average CRR (kg/ton) \a\................             5.1             4.7             4.7             4.8
Tire Pressure Systems:
    ATIS........................................            100%            100%            100%            100%
    TPMS........................................
        Average Pressure System Reduction (%)               1.2%            1.2%            1.2%            1.2%
         \a\....................................
Weight Reduction:
        Weight (lb) \b\.........................
----------------------------------------------------------------------------------------------------------------
Notes:
A blank cell indicates a zero value.
\a\ Combines projected adoption rates with performance levels shown in Table IV-9.
\b\ This set of adoption rates did not apply any assumed weight reduction to meet these standards for these
  trailers.

      Table IV-15--Projected Adoption Rates and Average Performance Parameters for Full-Aero Short Box Vans
----------------------------------------------------------------------------------------------------------------
                   Technology                                    Short box dry & refrigerated vans
----------------------------------------------------------------------------------------------------------------
                   Model year                          2018            2021            2024            2027
----------------------------------------------------------------------------------------------------------------
Aerodynamic Technologies:
    Bin I.......................................
    Bin II......................................  ..............            100%
    Bin III.....................................  ..............  ..............            100%             40%
    Bin IV......................................  ..............  ..............  ..............             60%
    Bin V.......................................
    Bin VI......................................
    Bin VII.....................................
        Average Delta CdA (m\2\) \b\............             0.0             0.1             0.4             0.6
Trailer Tire Rolling Resistance:
    Level 1.....................................
    Level 2.....................................  ..............  ..............  ..............              5%
    Level 3.....................................            100%
    Level 4.....................................  ..............            100%            100%             95%
        Average CRR (kg/ton) \b\................             5.1             4.7             4.7             4.8
Tire Pressure Systems:
    ATIS........................................            100%            100%            100%            100%
    TPMS........................................
        Average Tire Pressure Reduction (%) \c\.            1.2%            1.2%            1.2%            1.2%
Weight Reduction:
        Weight (lb) \b\.........................
----------------------------------------------------------------------------------------------------------------
Notes:
A blank cell indicates a zero value.
\a\ The majority of short box trailers are 28 feet in length. We recognize that they are often operated in
  tandem, which limits the technologies that can be applied (for example, boat tails).
\b\ Combines projected adoption rates with performance levels shown in Table IV-9.

\c\ This set of adoption rates did not apply any assumed weight reduction to meet these standards for these
  trailers.

    The agencies proposed that the partial-aero box vans would track
with the full-aero van standards until MY 2024. 80 FR 40257. Wabash
commented that partial-aero box vans should be exempt starting in MY
2021 since partial-aero vans cannot use multiple devices. The agencies
reconsidered the proposed partial-aero standards and recognize that it
would likely be difficult to meet the proposed MY 2024 standards
without the use of multiple devices and yet partial-aero trailers, by
definition, are restricted from using multiple devices. For these
reasons, the agencies redesigned the partial-aero standards, such that
trailers with qualifying work-performing equipment can meet standards
that would be achievable with the use of a single aerodynamic device
throughout the program, similar to the MY 2018 standards. The partial-
aero standards do, however, increase in stringency slightly in MY 2021,
to reflect the broader use of improved lower rolling resistance tires.

       Table IV-16--Projected Adoption Rates and Average Performance Parameters for Partial-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
                   Technology                       Partial-aero long box vans      Partial-aero short box vans
----------------------------------------------------------------------------------------------------------------
                   Model year                          2018            2021+           2018            2021+
----------------------------------------------------------------------------------------------------------------
Aerodynamic Technologies:
    Bin I.......................................
    Bin II......................................  ..............  ..............  ..............            100%
    Bin III.....................................            100%            100%
    Bin IV......................................
    Bin V.......................................
    Bin VI......................................
    Bin VII.....................................
        Average Delta CdA (m\2\) \b\............             0.5             0.5             0.0             0.1
Trailer Tire Rolling Resistance:
    Level 1.....................................
    Level 2.....................................
    Level 3.....................................            100%  ..............            100%
    Level 4.....................................  ..............            100%  ..............            100%
        Average CRR (kg/ton) \b\................             5.1             4.7             5.1             4.7
Tire Pressure Systems:
    ATIS........................................            100%            100%            100%            100%
    TPMS........................................
        Average Pressure System Reduction (%)               1.2%            1.2%            1.2%            1.2%
         \a\....................................
Weight Reduction:
        Weight (lb) \b\.........................
----------------------------------------------------------------------------------------------------------------
Notes:
A blank cell indicates a zero value.
\a\ Combines projected adoption rates with performance levels shown in Table IV-9.
\b\ This set of adoption rates did not apply weight reduction to meet these standards for these trailers.

    The adoption rates shown in these tables are one set of many
possible combinations that box trailer manufacturers could apply to
achieve the same average stringency. If a manufacturer chose these
adoption rates, a variety of technology options exist within the
aerodynamic bins, and several models of LRR tires exist for the levels
shown. Alternatively, technologies from other aero bins and tire levels
could be used to comply. It should be noted that since the standards
for box vans are all performance-based, box van manufacturers are not
limited to specific aerodynamic and tire technologies in their
compliance choices. Certain types of weight reduction, for example, may
be used as part of a compliance pathway. See RIA Chapter <IP_ADDRESS>.1 for
other example compliance pathways that include weight reduction.
    Similar to our analyses of the baseline cases, the agencies derived
a single set of performance parameters for each subcategory by
weighting the performance levels included in Table IV-9 by the
corresponding adoption rates. These performance parameters represent a
compliant vehicle for each trailer subcategory and are presented as
average values in the Table IV-14 through Table IV-16.
(ii) Tire Technologies for Non-Aero Box Vans and Non-Box Trailers
    Neither non-aero vans (i.e., those with two or more work-related
special components), nor non-box trailers are shown in the tables
above. This is because we are adopting design-based (i.e., technology-
based) standards for these trailers, not performance-based standards.
Manufacturers of these trailers do not need to use aerodynamic
technologies, but they need to install the lower rolling resistance
tires and tire pressure systems established by this program (see
Section IV.C.(2)). Compared to manufacturers that needed aerodynamic
technologies to comply, the approach for non-aero box trailers and non-
box trailers results in a significantly lower compliance burden for
manufacturers by reducing the amount of tracking and eliminating the
need to calculate a compliance value (see Section IV.E.). The agencies
are adopting these design standards, which can be assumed to be 100
percent adoption, in two stages. In MY 2018, the non-box trailer
standards require manufacturers to use tires meeting a rolling
resistance of Level 2 or better and to install tire pressure systems.
In MY 2021, non-box trailers standards require tire pressure systems
and LRR tires at Level 3 or better. Non-aero box vans, which we believe
are largely at a baseline rolling resistance Level 2 today, require
tire pressure monitoring systems with Level 3 tires in MY 2018 and
Level 4 tires in MY 2021 and later.
    We received comment that manufacturers were concerned about the
cost and availability of ATIS for the trailer industry. Still, based on
comments about TPMS and further evaluations by the agencies, we are
including TPMS as an additional option for tire pressure systems in the
trailer program, as discussed in Section IV.D.(1)(c) above. Non-aero
vans and

non-box trailers are compliant if they have appropriate lower rolling
resistance tires and either TPMS or ATIS.
(e) Derivation of the Trailer Standards
    The agencies applied the average performance parameters from Table
IV-14 and Table IV-15 as input values to the GEM vehicle simulation to
derive the HD Phase 2 fuel consumption and CO2 emissions
standards for each long and short full-aero box van subcategory. These
full-aero van standards are shown in Table IV-17. Similarly, the
average performance parameters from Table IV-16 were used to calculate
the partial-aero van standards shown in Table IV-18. The design
standards for non-box trailer and non-aero box van are summarized in
Table IV-19.
    Over the four stages of the trailer program, the full-aero box vans
longer than 50 feet are projected to reduce their CO2
emissions and fuel consumption by two percent, five percent, seven
percent and nine percent compared to their average baseline cases in
Table IV-13. Full-aero box vans 50-feet and shorter will achieve
reductions of one percent, two percent, four percent and six percent
compared to their average baseline cases. The partial-aero long and
short box van standards will reduce CO2 and fuel consumption
by six percent and four percent, respectively, by MY 2021. The tire
technologies used on non-box and non-aero box trailers are projected to
provide reductions of two percent in the first stage and three percent
in MY 2021 and later.

                                  Table IV-17--Standards for Full-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
                                            Subcategory                Dry van              Refrigerated van
             Model year              ---------------------------------------------------------------------------
                                              Length              Long        Short         Long        Short
----------------------------------------------------------------------------------------------------------------
2018-2020...........................  EPA Standard                   81.3        125.4         83.0        129.1
                                       (CO[ihel2] Grams per
                                       Ton-Mile).
                                      Voluntary NHTSA             7.98625     12.31827      8.15324     12.68173
                                       Standard (Gallons per
                                       1,000 Ton-Mile).
2021-2023...........................  EPA Standard                   78.9        123.7         80.6        127.5
                                       (CO[ihel2] Grams per
                                       Ton-Mile).
                                      NHTSA Standard              7.75049     12.15128      7.91749     12.52456
                                       (Gallons per 1,000
                                       Ton-Mile).
2024-2026...........................  EPA Standard                   77.2        120.9         78.9        124.7
                                       (CO[ihel2] Grams per
                                       Ton-Mile).
                                      NHTSA Standard              7.58350     11.87623      7.75049     12.24951
                                       (Gallons per 1,000
                                       Ton-Mile).
2027+...............................  EPA Standard                   75.7        119.4         77.4        123.2
                                       (CO[ihel2] Grams per
                                       Ton-Mile).
                                      NHTSA Standard              7.43615      11.7288      7.60314     12.10216
                                       (Gallons per 1,000
                                       Ton-Mile).
----------------------------------------------------------------------------------------------------------------

                                Table IV-18--Standards for Partial-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
                                            Subcategory                Dry van              Refrigerated van
             Model year              ---------------------------------------------------------------------------
                                              Length              Long        Short         Long        Short
----------------------------------------------------------------------------------------------------------------
2018-2020...........................  EPA Standard                   81.3        125.4         83.0        129.1
                                       (CO[ihel2] Grams per
                                       Ton-Mile).
                                      Voluntary NHTSA             7.98625     12.31827      8.15324     12.68173
                                       Standard (Gallons per
                                       1,000 Ton-Mile).
2021+...............................  EPA Standard                   80.6        123.7         82.3        127.5
                                       (CO[ihel2] Grams per
                                       Ton-Mile).
                                      NHTSA Standard              7.91749     12.15128      8.08448     12.52456
                                       (Gallons per 1,000
                                       Ton-Mile).
----------------------------------------------------------------------------------------------------------------

               Table IV-19--Design-Based Tire Standards for Non-Box Trailers and Non-Aero Box Vans
----------------------------------------------------------------------------------------------------------------
                Model year                       Tire technology          Non-box trailers    Non-aero box vans
----------------------------------------------------------------------------------------------------------------
2018-2020................................  Tire Rolling Resistance                   <=6.0                <=5.1
                                            Level (kg/ton).
                                           Tire Pressure System.......        TPMS or ATIS         TPMS or ATIS
2021+....................................  Tire Rolling Resistance                   <=5.1                <=4.7
                                            Level (kg/ton).
                                           Tire Pressure System.......        TPMS or ATIS         TPMS or ATIS
----------------------------------------------------------------------------------------------------------------

(f) Technology Costs for the Trailer Standards
    The agencies evaluated the incremental technology costs for 53-foot
dry and refrigerated vans and 28-foot dry vans. (As explained above, we
believe these length trailers are representative of the majority of
trailers in the long and short box van subcategories, respectively.) We
identified costs for each technology package and projected the costs
for each year of the program. A summary of the technology costs is
included in Table IV-20 through Table IV-23 for MYs 2018 through 2027,
with additional details available in the RIA Chapter 2.12. Costs shown
in the following tables are for the specific model year indicated and
are incremental to the average baseline costs, which includes some
level of adoption of these technologies as shown in Table IV-13.
Therefore, the technology costs in the following tables reflect the
average cost expected for each of the indicated trailer classes across
the fleet. Note that these costs do not represent actual costs for the
individual components because they are relative to the costs of the MY
2018 baselines which are expected due to market-driven adoption of the
technologies. For more on the estimated technology costs exclusive of
adoption rates, refer to Chapter 2.12 of the RIA. These costs include
indirect costs via markups and reflect lower costs over time due to
learning impacts. For a description of the markups and learning impacts
considered in this analysis and how technology costs for other years
are thereby affected, refer to Chapter 7 of the RIA.

                                        Table IV-20--Trailer Technology Incremental Costs in the 2018 Model Year
                                                                         [2013$]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Long vans,               Short vans,
                                                                Long vans,    partial    Short vans,    partial     Long vans,  Short vans,    Non-box
                                                                full aero       aero      full aero       aero       no aero      no aero
--------------------------------------------------------------------------------------------------------------------------------------------------------
Aerodynamics.................................................         $367         $742           $0           $0           $0           $0           $0
Tires........................................................            2           40            1           20           40           20           28
Tire inflation system........................................          347          659          338          494          421          210          421
                                                              ------------------------------------------------------------------------------------------
    Total....................................................          716        1,441          339          514          461          231          448
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                        Table IV-21--Trailer Technology Incremental Costs in the 2021 Model Year
                                                                         [2013$]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Long vans,               Short vans,
                                                                Long vans,    partial    Short vans,    partial     Long vans,  Short vans,    Non-box
                                                                full aero       aero      full aero       aero       no aero      no aero
--------------------------------------------------------------------------------------------------------------------------------------------------------
Aerodynamics.................................................         $743         $679         $450         $475           $0           $0           $0
Tires........................................................           17           49            9           25           49           25           23
Tire inflation system........................................          321          609          313          457          389          195          389
                                                              ------------------------------------------------------------------------------------------
    Total....................................................        1,081        1,337          772          957          438          219          412
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                        Table IV-22--Trailer Technology Incremental Costs in the 2024 Model Year
                                                                         [2013$]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Long vans,               Short vans,
                                                                Long vans,    partial    Short vans,    partial     Long vans,  Short vans,    Non-box
                                                                full aero       aero      full aero       aero       no aero      no aero
--------------------------------------------------------------------------------------------------------------------------------------------------------
Aerodynamics.................................................         $899         $645         $879         $451           $0           $0           $0
Tires........................................................           11           48            6           24           48           24           27
Tire inflation system........................................          294          558          286          418          357          178          357
                                                              ------------------------------------------------------------------------------------------
    Total....................................................        1,204        1,251        1,171          894          405          202          383
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                                        Table IV-23--Trailer Technology Incremental Costs in the 2027 Model Year
                                                                         [2013$]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Long vans,               Short vans,
                                                                Long vans,    partial    Short vans,    partial     Long vans,  Short vans,    Non-box
                                                                full aero       aero      full aero       aero       no aero      no aero
--------------------------------------------------------------------------------------------------------------------------------------------------------
Aerodynamics.................................................       $1,069         $623         $921         $436           $0           $0           $0
Tires........................................................           22           44           11           22           44           22           16
Tire inflation system........................................          279          529          272          397          338          169          338
                                                              ------------------------------------------------------------------------------------------
    Total....................................................        1,370        1,196        1,204          855          382          191          354
--------------------------------------------------------------------------------------------------------------------------------------------------------

(3) Consistency of the Trailer Standards With the Agencies' Statutory
Obligations
    The agencies have determined that the standards presented in the
Section IV.C.(2), are the maximum feasible and appropriate under the
agencies' respective authorities, considering lead time, cost, and
other factors. The agencies' decisions on the stringency and timing of
the trailer standards focused on available technology and the
consequent emission reductions and fuel efficiency improvements
associated with use of the technology, while taking into account the
circumstances of the trailer manufacturing sector. Trailer
manufacturers are subject to first-time emission control and fuel
consumption regulation under the trailer standards. These manufacturers
are in many cases small businesses, with limited resources to master
the mechanics of regulatory compliance. Thus, the agencies are
providing ample and reasonable time for trailer manufacturers to become
familiar with the requirements and the new compliance regime.
    The stringency of the standard is predicated on more widespread
deployment of tire technologies that are already in commercial use and
existing aerodynamic devices combinations that we believe will be
further optimized in the near-term. The availability, feasibility, and
level of effectiveness of these technologies are well-documented. In
developing the standards, we also took into account not just the
capabilities of the technologies, but also how the use of these
technologies is likely to expand under the trailer program, considering
factors like degree of market penetration over time and the effect of
different operational patterns for different trailer types (Section
IV.D.(2) above). For example, some commenters point out that trailers
operating at lower speeds will achieve smaller CO2 and fuel
consumption reductions than they will at highway speeds. The agencies
acknowledge this fact, and account for a fraction of trailer operation
at slower speeds. All long box vans are evaluated with 5 percent of
their miles at low speed operation and all short vans are evaluated
with 17 percent low speed miles. While we cannot predict individual
trailer use, we believe these

values are a reasonable estimate of an industry average.\363\ Our
analysis in RIA Chapter <IP_ADDRESS>.1 shows that skirts will provide short
trailers with at least 1 percent improvement and long trailers with at
least 4 percent improvement at 55 mph. We expect most trailers spend at
least some of their miles at 55 mph or faster in use and will gain
similar benefits during those speeds. We also show that even trailers
operating under fully transient conditions (combining slower and faster
operation) will experience a small improvement from use of trailer
skirts.
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    \363\ Memorandum to Docket EPA-HQ-OAR-2014-0827, ``Comparison of
GEM Drive Cycle Weightings and Fleet Data Provided by Utility
Trailer Manufacturing Co. in Public Comments'', July 2016.
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    The agencies do not believe that there is any issue of
technological feasibility of the levels of the standards and the time
line for implementing them in the final trailer program. The agencies
considered cost and the sufficiency of lead-time, including lead-time
not only to deploy technological improvements, but, as just noted, also
for this industry sector to assimilate for the first time the
compliance mechanisms of the trailer program.
    The highest cost shown in Table IV-23 is associated with the
standard for long dry vans. We project that the average cost per
trailer to meet the MY 2027 standards for these trailers will be about
$1,400, which is less than 10 percent of the cost of a new dry van
trailer (estimated to be about $20,000). Other trailer types have lower
projected technology costs, and many have higher purchase prices. As a
result, we project that the per-trailer costs for all trailers covered
in this regulation will be less than 10 percent of the cost of a new
trailer.
    The agencies regard these costs as reasonable. We project that most
customers will rapidly recover the initial cost of these technologies
due to the associated fuel savings, usually in two years. As discussed
in Section IX.M and RIA Chapter 7.2.4, this payback is for tractors and
trailers together, and includes both long and short-haul. This payback
period is generally considered reasonable in the trailer industry for
investments that reduce fuel consumption.\364\ Although longer paybacks
will occur for some trailers, we do not project that any trailers will
achieve lifetime fuel savings less than the cost of the technologies.
In addition, the agencies estimate the cost per metric ton of
CO2eq reduction without considering fuel savings to be $36
for tractor-trailers in 2030 which compares favorably with the levels
of cost effectiveness the agencies found to be reasonable for light
duty trucks.\365\
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