The agencies are predicating part of the stringency of the final
vocational vehicle standards on performance of two types of axle
technologies. The first is advanced low friction axle lubricants and
efficiency as demonstrated using the separate axle test procedure
described in the RIA Chapter 3.8 and 40 CFR 1037.560. The agencies
received adverse comment on the proposal to assign a fixed 0.5 percent
improvement for this technology. In consideration of comments, the
agencies are instead assigning default axle efficiencies to all
vocational vehicles. Manufacturers may submit test data to over-ride
axle efficiency values in GEM. Our cost analysis for the final
rulemaking includes maintenance costs of replacing axle lubricants on a
periodic basis. See the RIA Chapter 7.1.3. Based on supplier
information, some advanced lubricants have a longer drain interval than
traditional lubricants. We are estimating the axle lubricating costs
for HHD to be the same as for tractors since those vehicles likewise
typically have three axles. However, for LHD and MHD vocational
vehicles, we scaled down the cost of this technology to reflect the
presence of a single rear axle. We expect that improved axle efficiency
is technically feasible on all vocational vehicles including custom
chassis. However, it's likely that axle suppliers may be more likely to
invest in design and lubrication improvements for high sales volume
products, such as axles that can serve both tractor and vocational
markets. Further, to the extent that extreme duty cycles require
lubricants with special performance features, it's likely that the most
advanced low-friction lubricants may not be feasible for some custom
chassis such as refuse trucks.
    The second axle technology applies only for HHD vocational
vehicles, which typically are built with two rear axles. Part time 6x2
configuration or axle disconnect is a design that enables one of the
rear axles to temporarily disconnect or otherwise behave as if it's a
non-driven axle. The agencies proposed to base the HHD vocational
vehicle standard on some use of both part time and full time 6x2 axles.
The agencies received adverse comment on the application of the
permanent 6x2 configuration for vocational vehicles. The disconnect
configuration is one that keeps both drive axles engaged only during
some types of vehicle operation, such as when operating at construction
sites or in transient driving where traction especially for
acceleration is vital. Instead of calculating a fixed improvement as at
proposal, the agencies have refined GEM to recognize this configuration
as an input, and the benefit will be actively simulated over the
applicable drive cycle. Effectiveness based on simulations with EPA
axle files is projected to be as much as one percent for HHD Regional
vehicles. Further information about this technology is provided in RIA
Chapter 2.4.5. The feasibility of this technology depends on whether
the baseline axle configuration is a 6x4 and whether the vehicle is
likely to spend significant amounts of time on the highway. For
vocational vehicles, this is largely limited to Regional and
Multipurpose HHD vehicles. To the extent that any motor homes and coach
buses with GVWR over 33,000 lbs are built with two rear axles, this
technology could be technically feasible. However, because these
vehicles generally operate on paved roads and may not need the traction
of a 6x4, a popular axle configuration for these vehicles is a
permanent 6x2.
(iii) Lower Rolling Resistance Tires
    Tires are the second largest contributor to energy losses of
vocational vehicles, as found in the energy audit conducted by Argonne
National Lab.\418\ The two most helpful sources of data in establishing
the projected vocational vehicle tire rolling resistance levels for the
final Phase 2 standards are the comments from RMA and actual
certification data for model

year 2014. At proposal, we projected that all vocational vehicle
subcategories could achieve average steer tire coefficient of rolling
resistance (CRR) of 6.4 kg/ton and drive tire CRR of 7.0 kg/ton by MY
2027. These new data have informed our analysis to enable us to
differentiate the technology projections by subcategory. The RMA
comments included CRR values for a wide range of vocational vehicle
tires, for rim sizes from 17.5 inches to 24.5 inches, for steer/all
position tires as well as drive tires. The RMA data, while illustrating
a range of available tires, are not sales weighted. The 2014
certification data include actual production volumes for each vehicle
type, thus both steer and drive tire population-weighted data are
available for emergency vehicles, cement mixers, school buses, motor
homes, coach buses, transit buses, and other chassis cabs. The
certification data are consistent with the RMA assessment of the range
of tire CRR currently available. We also agree with RMA's suggestion to
set a future CRR level where a certain percent of current products can
meet future GEM targets. We disagree with RMA that the MY 2027 target
should be a level that 50 percent of today's product can meet. With
programmatic averaging, such a level would mean essentially no
improvements overall from tire rolling resistance, because today when
manufacturers comply on average, half their tires are above the target
and half are below. Further, with Phase 2 GEM requiring many more
vehicle inputs than tire CRR, manufacturers have many more degrees of
freedom to meet the performance standard than they do in Phase 1. In
these final rules, the agencies are generally projecting adoption of
LRR tires in MY 2027 at levels currently met by 25 to 40 percent of
today's vocational products, on a sales-weighted basis.\419\ We are
differentiating the improvement level by weight class and duty cycle,
recognizing that heavier vehicles designed for highway use can
generally apply tires with lower rolling resistance than other vehicle
types, and will see a greater benefit during use. None of the rolling
resistance levels projected for adoption in MY 2027 are lower than the
25th percentile of tire CRR on actual vocational vehicles sold in MY
2014. Thus, we believe the improvements will be achievable without need
to develop new tires not yet available. Further details are presented
in the RIA Chapter 2.9.
---------------------------------------------------------------------------

    \418\ See Argonne National Laboratory 2009 report, Note 411,
page 91.
    \419\ See memorandum dated May 2016 titled, Vocational Vehicle
Tire Rolling Resistance Certification Data.
---------------------------------------------------------------------------

    In simulation, the benefit of LRR tires is reflected in GEM
differently for vehicles of different weight classes and duty cycles.
Based on simulations using the projected tire CRR, the agencies project
fuel efficiency improvements by MY 2027 for LRR tires on Regional
vocational vehicles between two and three percent, for Multipurpose
vehicles between one and three percent, and for Urban vehicles up to
one percent. This technology is also feasible on all custom chassis,
with similarly larger improvements feasible for coach buses and motor
homes with typically regional drive cycles, and similarly smaller
improvements feasible for school and transit buses, refuse trucks, and
concrete mixers with typically urban drive cycles.
    As proposed, the agencies will continue the light truck (LT) tire
CRR adjustment factor that was adopted in Phase 1. 80 FR 40299; see
generally 76 FR 57172-57174. In Phase 1, the agencies developed this
adjustment factor by dividing the overall vocational test average CRR
of 7.7 by the LT vocational average CRR of 8.9. This yielded an
adjustment factor of 0.87. Because the MY 2014 certification data for
LHD vocational vehicles may have included some CRR levels to which this
adjustment factor may have already been applied, and because we did not
receive adverse comment on our proposal to continue this, the agencies
have concluded that we do not have a basis to discontinue allowing the
measured CRR values for LT tires to be multiplied by a 0.87 adjustment
factor before entering the values in the GEM for compliance.
    In Table V-15, the descriptors 1v through 5v refer to levels of
rolling resistance that have been identified among the population of
tires installed on vocational vehicles certified for MY 2014. Each of
these levels is in production today and represents tires that have been
fitted on a certified vehicle. The agencies have defined these levels
for purposes of estimating the manufacturing costs associated with
applying improved tire rolling resistance to vocational vehicles. These
levels are not applicable for estimating degrees of improvement or
costs of LRR tires on tractors, trailers, or HD pickups and vans as
part of this rulemaking. Furthermore, these levels do not represent the
full range of tire CRR available for vocational vehicles. There are
both steer and drive tires on certified vocational vehicles today with
CRR ranging from 5 kg/ton to 15 kg/ton. We expect this full range of
tires will continue to be available in the market well into the future.

            Table V-15--Defined Levels of Vocational Tire CRR
------------------------------------------------------------------------
                                                           Range   Range
           Rolling resistance level descriptor             min.    max.
------------------------------------------------------------------------
LRR level 1v............................................     7.5     8.1
LRR level 2v............................................     7.0    7.49
LRR level 3v............................................     6.6    6.99
LRR level 4v............................................     6.3    6.59
LRR level 5v............................................     5.8    6.29
------------------------------------------------------------------------

(iv) Workday Idle Reduction
    The Phase 2 idle reduction technologies considered for vocational
vehicles are those that reduce workday idling, unlike the overnight or
driver rest period idling of sleeper cab tractors. Idle reduction
technology is one type of technology that is particularly duty-cycle
dependent. In light of new information, the agencies have learned that
our proposal had mischaracterized the idling operation of vocational
vehicles, significantly underestimating the extent of this mode of
operation, and incorrectly calculating it using a drive idle cycle when
significant idling also occurs while parked. As described above in
Section V.B.(1), in these final rules we have revised our test cycles
to better reflect real world idle operation, including both parked idle
and drive idle test conditions. At proposal, we identified two types of
idle reduction technologies to reduce workday idle emissions and fuel
consumption for vocational vehicles: neutral idle and stop-start. After
considering the new duty cycle information and the many comments
received, we are basing our final vocational vehicle standards in part
on the performance of three types of workday idle reduction
technologies: neutral idle, stop-start, and automatic engine shutdown;
which we believe are effective, feasible, and cost-effective, as
discussed further in this section.
    Neutral idle is essentially a transmission technology, but it also
requires a compatible engine calibration. Torque converter automatic
transmissions traditionally place a load on engines when a vehicle
applies the brake while in drive, which we call curb idle transmission
torque (CITT). When an engine is paired with a manual or automated
manual transmission, the CITT is naturally lower than when paired with
an automatic, as a clutch disengagement must occur for the vehicle to
stop without stalling the engine. We did not receive adverse comment on
our proposal to include this technology in our standard-setting for
vocational vehicles. The engineering

required to program sensors to detect the brake position and vehicle
speed, and enable a smooth re-engagement when the brake pedal is
released makes this a relatively low complexity technology that can be
deployed broadly. Navistar commented that idle reduction strategies
must have sufficient engine, aftertreatment and occupant protections in
place such that any fuel cost savings are a net benefit for the owner/
operator without compromising safety. We agree, and for neutral idle we
believe an example of an allowable override is if a vehicle is stopped
on a hill. Skilled drivers operating manual transmissions can safely
engage a forward gear from neutral when stopped on upslopes with
minimal roll-back. With an AT, the vehicle's computer would need to
handle such situations automatically. In addition, engagement of the
PTO while driving will be an allowable over-ride condition. In the
Phase 2 certification process, transmission suppliers will attest
whether the transmission has this feature present and active, and
certifying entities will be able to enter Yes or No as a GEM input for
the applicable field. The effectiveness of this technology will be
calculated using data points collected during the engine test, and the
appropriate fueling over the drive idle cycle and the transient cycle
will be used. Based on GEM simulations using the final vocational
vehicle test cycles, the agencies project neutral idle to provide fuel
efficiency improvements up to seven percent for diesel vehicles, and up
to two percent for gasoline vehicles, depending on the regulatory
subcategory.\420\ The lesser effectiveness for gasoline vehicles is due
to lower curb idle transmission torque present in the baseline
configurations for gasoline than the diesel vehicles, as documented in
the SwRI report.\421\
---------------------------------------------------------------------------

    \420\ See spreadsheet file dated July 2016 titled,
``FRM_Vocational-Standards_GEMpostprocess.xls''. See EPA-HQ-OAR-
2014-0827.
    \421\ See Reinhart 2015, Note 345 above.
---------------------------------------------------------------------------

    Neutral idle may be programmed on any automatic transmission, and
can reasonably be applied for vocational vehicles where this feature
would not frequently encounter an over-ride condition. Vehicles with
high PTO operation can apply this technology, although they would see
reduced effectiveness in use.
    Automatic engine shutdown (AES) is an engine technology that is
widely available in the market today, but has seen more adoption in the
tractor market than for vocational vehicles. Although we did not
propose to include this technology, we received many comments
suggesting this would be appropriate. Some commenters may have
conflated the concept of stop-start with AES, such as a comment we
received asking us to consider the on-board need to power accessories
while the vehicle is in stationary mode. We believe that automatic
engine shutdown is effective and feasible for many different types of
vehicles, depending on how significant a portion of the work day is
spent while parked. Most truck operators are aware of the cost of fuel
consumed while idling, and importantly, the wear on the engine due to
idling. Engine manufacturers caution owners to monitor the extent of
idling that occurs for each work truck and to reduce the oil change
interval if the idle time exceeds ten percent of the work day.\422\
Accordingly, many utility truck operators track their oil change
intervals in engine hours rather than in miles.
---------------------------------------------------------------------------

    \422\ See Ford powerstroke guide at https://www.fleet.ford.com/truckbbas/non-html/DeiselTips/DLSIDLETIMESS.pdf (accessed March
2016); see also Cummins maintenance schedule, available at http://www.cumminsbridgeway.com/pdf/parts/Recommended_Maintenance_Schedule.pdf (accessed March 2016).
---------------------------------------------------------------------------

    NTEA provided the agencies with a report with survey results on
which work truck fleets are adopting AES with backup power, and their
reasons for doing so.\423\ The most common reason given in the survey
is to allow an engine to shut down and still have vehicle power
available to run flashing safety lights. Some vocational vehicles also
need to conduct work using a power take-off (PTO) while stationary for
hours, such as on a boom truck. The agencies are adopting an allowable
AES over-ride for PTO use. Technologies that can reduce fuel
consumption during this type of high-load idle are discussed below in
V.C.(1)(c)(iii). We are also adopting an allowable AES over-ride if the
battery state of charge drops below a safe threshold. This would ensure
there is sufficient power to operate any engine-off accessories up to a
point where the battery capacity has reached a critical point. Where a
vocational vehicle has such extensive stationary accessory demands that
an auxiliary power source is impractical or that an over-ride condition
would be experienced frequently, we would not consider AES to be
feasible. In the Phase 2 certification process, engine suppliers will
attest whether this feature is present and tamper-proof, and certifying
entities will be able to enter Yes or No as a GEM input for the
applicable field.\424\ As with neutral idle described above, the
effectiveness of AES will be calculated in GEM using data obtained
through engine testing. The appropriate data points over the parked
idle cycle will be used for calculating the fueling. Based on GEM
simulations using the final vocational vehicle test cycles, the
agencies project AES to provide fuel efficiency improvements ranging
from one to seven percent, depending on the regulatory subcategory.
---------------------------------------------------------------------------

    \423\ NTEA, 2015 Work Truck Electrification and Idle Management
Study.
    \424\ We will consider non-tamper-proof AES as off-cycle
technologies for a lesser credit.
---------------------------------------------------------------------------

    The agencies proposed to predicate the vocational vehicle standards
in part on 70 percent adoption of stop-start in MY 2027. We received
numerous comments from manufacturers and suppliers with concerns about
all aspects of this technology, including its feasibility, its
effectiveness, and the lead time to make it commercially available. As
discussed above, our assessment of workday idle reduction technologies
has been refined since proposal, and part of this refinement includes
less reliance on adoption of stop-start than at proposal.
    Stop-start is a technology that requires an integration between
engine and vehicle systems, and is seeing increasing acceptance in
today's passenger vehicle market. The agencies are aware that for a
vocational vehicle's engine to turn off during workday driving
conditions, there must be a minimal reserve source of energy to
maintain engine-protection and safety functions such as power steering,
transmission pressure, engine lubrication and cooling, among others. As
such, stop-start systems can be viewed as having a place on the low-
cost end of the hybridization continuum. Effenco commented that a
minimum of additional hardware is required to deliver enough power to
frequently and seamlessly restart a large engine as well as to keep
accessories and equipment operational with the engine turned off.
Navistar commented persuasively that coking can occur if the cooling
and lubricating oil is removed. The agencies therefore would consider
electrified water and oil pumps to be part of the stop-start technology
package. However, we must be clear to distinguish this technology from
the AES described above. Stop-start technologies will be recognized
only over the drive idle cycle and the transient cycle in GEM, not the
parked idle cycle (whereas AES is recognized only over the parked idle
cycle). Accordingly, the purpose of the additional hardware is to
protect the engine for short duration stops such as at traffic lights,
not to power accessories while the vehicle is parked.
    Volvo commented that stop-start is not feasible for HHD engines
(generally 11L and larger), and claims engine

development costs will be very high since stop-start cycling tests can
only be accelerated by a limited amount before the failure mechanisms
are altered. However, their objections relate more to the challenges of
stop-start for HHD engines and do not actually show the technology to
be infeasible. Although we disagree with Volvo that stop-start is
infeasible for HHD engines, we understand it may require more
development time and cost than for engines in lighter vehicles. It's
possible that some time may be needed for development work where
manufacturers elect to shift away from reliance on batteries for
starting the engine and begin to rely instead on ultracapacitors, which
do not have the same problems with cold weather operation and long term
fatigue as do batteries.\425\ Volvo and EMA commented that main and rod
bearings as well as other bearing surfaces would need to be
strengthened and improvements may be needed for starters and
lubrication systems. We agree with commenters that this type of
development work would likely be part of bringing this technology to
the vocational vehicle market, and thus we have included costs for
upgrades similar to those described for all sizes of engines, not just
those over 11L. In the event that an engine manufacturer needs to delay
adoption of stop start to roll these changes in to a planned platform
redesign, we believe our relatively modest adoption rate of 30 percent
in MY 2027 will accommodate this. Descriptions of costs for stop-start
may be found in the RIA Chapter <IP_ADDRESS>.
---------------------------------------------------------------------------

    \425\ Maxwell Technologies, How Ultracapacitors Improve Starting
Reliability for Truck Fleets, 2016.
---------------------------------------------------------------------------

    We are not aware of stop-start systems that are commercially
available for conventional vocational vehicles today, but this feature
is available as part of some current hybrid systems. We are aware of
one supplier who is demonstrating today a capacitor-based stop-start
system with on-board electronics sufficient to protect a HHD engine and
even power a PTO.\426\ Furthermore, other manufacturers and suppliers
are researching this.\427\ Therefore we are confident heavy-duty stop-
start systems for conventional vehicles will be feasible in the time
frame of Phase 2. Where stop-start is relied upon as part of a
certified configuration with components installed by a secondary
manufacturer, these will be subject to specifications and installation
instructions of the certifying manufacturer.
---------------------------------------------------------------------------

    \426\ See comment submitted by Effenco describing such a system
designed for a refuse packer.
    \427\ See phone log for L. Steele, conversation with B. Van
Amburg, May 2016.
---------------------------------------------------------------------------

    In response to comments, we are adopting some permissible over-ride
conditions under which a stop-start system may either restart sooner
than otherwise or not shut down an engine. Navistar, Waste Management
and others commented that vehicles with a significant power take-off
(PTO) load will not be able to accommodate start/stop technology. As
with neutral idle, we agree that engagement of the PTO while driving
should be an allowable over-ride condition, as there are some vehicles
that must conduct PTO work while underway. For example, cement mixers
must continually rotate the drum and refuse trucks routinely compact
their load throughout their neighborhood collection activity.
Additional over-rides are discussed in the RIA Chapter <IP_ADDRESS>. If a
manufacturer designs a system that does not need as many over-rides due
to additional electrification or other on-board systems, then an
application for off-cycle credit may be submitted, to recognize a
greater effectiveness. The regulations at 40 CFR 1037.660 specify the
allowable over-rides.
    The effectiveness of stop-start as recognized in GEM will be
engine-dependent. Engines with high emissions/fuel consumption at idle
will see greater reductions. Also, vehicles that idle frequently will
see greater reductions. Based on GEM simulations using the final
vocational vehicle test cycles, the agencies project stop-start to
provide fuel efficiency improvements up to 14 percent for diesel
vehicles, and up to 11 percent for gasoline vehicles, depending on the
regulatory subcategory. See RIA <IP_ADDRESS>. The data points for
calculating the fueling over the transient and drive idle cycles are
obtained from the engine map, and vehicle certifiers may input Yes or
No when running GEM, to indicate whether the engine shuts off within
five seconds of zero vehicle speed with the service brake applied.
Allison commented that GEM should calculate fueling only for a couple
seconds before assuming the engine shuts down in a stop-start system.
Navistar suggested that we recognize that some fleets--e.g. heavy haul,
refuse, mixer trucks and tow trucks--may elect to have this feature set
as a programmable parameter to ensure maximum safety is maintained. We
believe that five seconds is appropriate because we expect a wide
variety of stop-start solutions to be deployed in the vocational
vehicle market, and we anticipate modest use of over-ride conditions.
Setting a shorter duration before shutdown could over-estimate the
reductions achieved by this technology in use. We believe this is a
fair way to represent that the system may not have the designed
effectiveness under all conditions.
    As with the other idle reduction technologies described above,
stop-start can reasonably be applied for vocational vehicles where this
feature would not frequently encounter an over-ride condition. Vehicles
with very little driving in transient conditions or with high PTO
operation can apply this technology, although they would see reduced
effectiveness in use. Chassis manufacturers certifying refuse trucks to
the optional custom chassis standards may enter Yes in the input field
in GEM for stop-start and the effectiveness will be computed based on
the default 350 hp engine with 5-speed HHD automatic transmission..
Manufacturers opting to certify refuse trucks to the primary standards
will have an option to be recognized for enhanced stop-start systems
through the powertrain test See RIA <IP_ADDRESS> and <IP_ADDRESS>.4.
    The agencies received comments from Allison Transmission where they
observed a seven percent NOX co-benefit of stop-start idle
reduction technology on transit buses. Daimler also commented that it
is investigating the potential for improving heat retention in the SCR
system via stop-start, but because of early stages of development it
cannot verify or quantify actual benefits. The agencies also conducted
independent NOX testing of engines at idle; however, the
data are not conclusive enough for the agencies to quantify the
NOX co-benefits of vocational workday idle reduction as part
of this rulemaking.
(v) Weight Reduction
    The agencies are predicating the final vocational vehicle standards
in part on use of material substitution for weight reduction. The
method of recognizing this technology is similar to the method used for
tractors. The agencies have created a menu of vocational chassis
components with fixed reductions in pounds that may be entered in GEM
when substituting a component made of a more lightweight material than
the base component made of mild steel. According to the 2009 TIAX
report, there are freight-efficiency benefits to reducing weight on
vocational vehicles that carry heavy cargo, and tax savings potentially
available to vocational vehicles that remain below excise tax weight
thresholds. This report also estimates that the cost effectiveness of
weight reduction over urban drive cycles is potentially greater than
the cost effectiveness of weight reduction

for long haul tractors and trailers. We are adopting as proposed a GEM
allocation of half the weight reduction to payload and half to reduced
chassis weight. We did not receive comment suggesting a different
weight allocation. The menu of components available for a vocational
vehicle weight reduction in GEM is presented in Section V.D.1 and in
the RIA Chapter 2.9, and is in the regulations at 40 CFR 1037.520. It
includes fewer options than proposed, due to persuasive comments from
Allison that aluminum transmission cases and clutch housings are
standard for automatic transmissions. The American Iron and Steel
Institute (AISI) commented that light weight values for high strength
steel should be adjusted upward, citing light-duty vehicle weight
reduction approaches using high strength steel and saying these
improvements should apply to the heavy-duty sector as well. AISI also
commented against the inclusion of any light-weight components as a
compliance mechanism for vocational vehicles without technical data to
support the weight saving values. At proposal, we based our weight
reduction values for class 8 vocational vehicles on the values adopted
for use in certifying tractors in Phase 1. We proposed to scale these
values down for lighter weight vehicles based either on number of axles
or other attributes based on engineering judgment. We also considered
information supplied by expert members of the Aluminum Transportation
Group.\428\ The final rules reflect revised weight reduction values in
response to the comments from AISI, and in further consideration of
information provided by the Aluminum Transportation Group. We were
unable to make use of the additional references submitted by AISI as
part of this standard-setting process, either because the technology
requires redesign rather than material substitution, or because we did
not see a way to apply the light-duty information to heavy-duty
vehicles. For setting stringency, however, we do not rely on any values
in the lookup table except those for aluminum wheels (although these
performance-based standards may be achieved in the manner deemed most
cost-effective by manufacturers). The stringency of the final
vocational vehicle standards for custom chassis transit buses and
vehicles in the primary program is based in part on use of aluminum
wheels in 10 positions on 3-axle vocational vehicles (250 lbs) and in 6
wheel positions on 2-axle vocational vehicles (150 lbs). Based on the
TIAX report and experience with the tractor program, the agencies are
confident that manufacturers who choose to incorporate weight reduction
on vocational vehicles will have a number of feasible material
substitution choices at the chassis level, which could add up to weight
savings of hundreds of pounds. The agencies do not have information
about any subset of vocational vehicles that would be unable to adopt
aluminum wheels, thus our projected adoption rates are much higher than
at proposal. Our projected adoption rate is revised upward based on the
determination that the technology package is smaller (fewer pounds
removed than at proposal) and that aluminum wheels are widely available
and feasible. We have learned through stakeholder outreach that weight-
sensitive applications such as ready-mix concrete and refuse have
already extensively applied weight reduction technologies, for freight
efficiency reasons.\429\ Therefore the agencies have not predicated the
standards for these custom chassis on further weight reduction.
---------------------------------------------------------------------------

    \428\ See email to L. Steele from D. Richman dated March 19,
2015 with attachments.
    \429\ See phone log for L. Steele, conversation with Terex (Aug
2015) and meeting with Autocar (April 2016).
---------------------------------------------------------------------------

    Based on the default payloads in GEM, and depending on the
vocational vehicle subcategory, the agencies estimate a reduction of
250 lbs would offer a fuel efficiency improvement of up to one percent
for HHD vehicles, and a reduction of 150 pounds would offer a fuel
efficiency improvement up to 0.8 percent for MHD vehicles, and up to
1.5 percent for LHD vehicles. See RIA <IP_ADDRESS>.
    The agencies received comment that the HD Phase 2 program should
recognize the enhanced benefit of weight reduction of rotating
components, but the agencies lack sufficient data to incorporate the
necessary programming in GEM to enable this feature. Manufacturers
wishing to obtain credit for lightweight components beyond those on the
menu in the regulations or for use of lightweighting technologies that
are more effective than we have projected, may apply for off-cycle
credits.
(vi) Electrified Accessories
    Although we did not propose to allow pre-defined credit for
electrified accessories as was proposed for tractors, we received
comment requesting that this be allowed for vocational vehicles. As
discussed above, the agencies are projecting that some electrified
accessories will be necessary as part of the development of stop-start
idle reduction systems for vocational vehicles. The technology package
for vocational stop-start includes costs for high-efficiency
alternator, electric water pump, electric cooling fan, and electric oil
pump. However, because the GEM algorithm for determining the fuel
benefit of stop-start does not account for any e-accessories, vehicles
certified with stop-start are also eligible to be certified using an
improvement value in the e-accessories column.
    Daimler, ICCT, Bendix, Gentherm, Navistar, Odyne, and CARB asked
the agencies to consider electric cooling fans, variable speed water
pumps, clutched air compressors, electric air compressors, electric
power steering, electric alternators, and electric A/C compressors.
ICCT cautioned that certain accessories would be recognized over an
engine test and credit should not be duplicated at the vehicle level.
Bosch suggested that high-efficiency alternators be considered, and
suggested use of a standard component-level test for alternators to
determine their efficiency, and establishment of a minimum efficiency
level that must be attained. Although there are industry-accepted test
procedures for measuring the performance of alternators, we do not have
sufficient information about the baseline level performance of
alternators to define an improved level that would qualify for a
benefit at certification. We are not able to set a fixed improvement
for electric cooling fans or clutched accessories due to similar
challenges related to baselines and defining the qualifying technology.
In consideration of ICCT's comment, we are not including water pumps
and oil pumps among the components eligible for a fixed improvement
because we believe that our engine test procedure will recognize
improvements that would be seen in the real world from electrifying
these. Thus, we believe it is appropriate to offer a fixed technology
improvement for use of electric power steering and an electric A/C
compressor as an input to GEM.
    The agencies have conducted modeling in GEM to compare
configurations with different default accessory loads, and have
demonstrated there is a measurable effect of reducing 1 kW of accessory
load for each vocational subcategory (see RIA <IP_ADDRESS>). The agencies
have incorporated information from this GEM modeling with information
from comments provided by ICCT, the TIAX 2009 technology report, CARB's
Driveline Optimization report, and the 2010 NAS report to assign fixed
improvement values for the defined technologies as

shown in Table V-16. These values are consistent with the TIAX study
that used 2 to 4 percent fuel consumption improvement for accessory
electrification, with the understanding that electrification of
accessories will have more effect in short haul/urban applications and
less benefit in line-haul applications.\430\ The RIA Chapter 2.9
explains how these effectiveness values were obtained.
---------------------------------------------------------------------------

    \430\ TIAX 2009, pp. 3-5.

          Table V-16--Effectiveness of Vocational E-Accessories
------------------------------------------------------------------------
                                  Effectiveness
           Technology                   %             Subcategories
------------------------------------------------------------------------
Electric A/C Compressor........             0.5  HHD.
                                            1.0  MHD & LHD.
Electric Power Steering........             0.5  Regional.
                                            1.0  Multipurpose & Urban.
------------------------------------------------------------------------

    Optimization and improved pressure regulation may significantly
reduce the parasitic load of the water, air and fuel pumps.
Electrification may result in a reduction in power demand, because
electrically-powered accessories (such as the air compressor or power
steering) operate only when needed if they are electrically powered,
but they impose a parasitic demand all the time if they are engine-
driven. In other cases, such as cooling fans or an engine's water pump,
electric power allows the accessory to run at speeds independent of
engine speed, which can reduce power consumption. Electrification of
accessories can individually improve fuel consumption, regardless of
whether the drivetrain is a strong hybrid. Some vocational vehicle
applications have much higher accessory loads than is assumed in the
default GEM configurations. In the real world, there may be some
vehicles for which there is a much larger potential improvement
available than those listed above, as well as some for which
electrification is not cost-effective. To date, accessory
electrification has been associated only with hybrids, although
CalStart commented they are optimistic that accessory electrification
will become more widespread among conventional vehicles in the time
frame of Phase 2.
    Electric power steering (EPS) or Electrohydraulic power steering
(EHPS) provides a potential reduction in CO2 emissions and fuel
consumption over hydraulic power steering because of reduced overall
accessory loads. This eliminates the parasitic losses associated with
belt-driven power steering pumps which consistently draw load from the
engine to pump hydraulic fluid through the steering actuation systems
even when the wheels are not being turned. EPS is an enabler for all
vehicle hybridization technologies since it provides power steering
when the engine is off. EPS is feasible for most vehicles with a
standard 12V system. Some heavier vehicles may require a higher voltage
system which may add cost and complexity.
    Manufacturers wishing to obtain credit for technologies that are
more effective than we have projected, or technologies beyond the scope
of this defined technology improvement, may apply for off-cycle
credits.
(vii) Tire Pressure Systems
TPMS
    The agencies did not propose to base the vocational vehicle
standards on the performance of tire pressure monitoring systems
(TPMS). However, we received comment that we should consider this
technology. See discussion in Section III.D.1.b. In addition to
comments related to tractors and trailers, RMA commented that TPMS can
also apply to the class 2b-6 vehicles, and if the agencies add TPMS to
the list of recognized technologies, that this choice should also be
made available to class 2b-6 vehicles. Bendix commented that TPMS is a
proven product, readily available from a number of truck, bus, and
motor coach OEMs. Autocar commented that TPMS is useful for refuse
truck applications. Tirestamp said that TPMS is ideal for trucks and
buses that are unable to apply ATIS due to difficulties plumbing air
lines externally of the axles. The agencies find these comments to be
persuasive. As a result, we are finalizing vocational vehicle standards
that are predicated on the performance of TPMS in all subcategories,
including all custom chassis except emergency vehicles and concrete
mixers. Available information indicates that it is feasible to utilize
TPMS on all vocational vehicles, though systems for heavy vehicles in
duty cycles where the air in the tires becomes very hot must be
ruggedized so that the sensors are protected from this heat. Such
devices are commercially available, though they cost more. To account
for this in our analysis, we have projected a lower adoption rate for
TPMS in Urban vehicles than for Regional or Multipurpose vehicles,
rather than by increasing the cost and applying an equal adoption rate.
We are assigning a fixed improvement in GEM for use of this technology
in vocational vehicles of one percent for Regional vehicles including
motor coaches and RV's (the same as for tractors and trailers) and 0.9
percent for Multipurpose, Urban, and other custom chassis vocational
vehicles, recognizing that the higher amount of idle is likely to
reduce the effectiveness for these vehicles. These values will be
specified as GEM inputs in the column designated for tire pressure
systems.
ATIS
    The agencies did not propose to base the vocational vehicle
standards on the performance of automatic tire inflation systems
(ATIS), otherwise known as central tire inflation (CTI). However, we
did receive comment indicating that it is feasible on some vocational
vehicles. Air CTI commented that central tire inflation is not only
feasible but enhances safety on vehicles such as dump trucks and heavy
haul vehicles that need higher tire pressures under certain driving
conditions, such as when loaded, but need lower tire pressures when
running empty or operating off-road. Tirestamp commented that ATIS can
be plumbed externally for trucks and buses, but such systems have a
propensity for damage and Autocar has provided information about how
much extra weight this plumbing adds to the chassis. ATA commented that
some onboard air pressure systems may not be able to pressurize tires
sufficiently for very heavy vehicles. The primary vocational vehicle
standards are not predicated on any adoption of this because the
agencies do not have sufficient information about which chassis will
have an onboard air supply for purposes

of an air suspension or air brakes. ATIS would logically only be
adopted for vehicles that already need an onboard air supply for other
reasons. Comments received for custom chassis were supportive of
standards predicated on ATIS for buses with air suspensions. These
comments are again persuasive. As a result, we are basing the optional
standards for refuse trucks, school buses, coach buses, and transit
buses in part on the adoption of ATIS. Although many motor homes have
onboard air supply for other reasons making ATIS technically feasible,
it is sufficiently costly that it is not practically feasible.
Furthermore, for the same reasons stated above about the disadvantages
of installing external plumbing for ATIS on some trucks and buses, we
have determined it is not feasible for emergency vehicles or concrete
mixers. Nonetheless, we are allowing vocational vehicles including all
custom chassis to obtain credit for the performance of ATIS through a
GEM input with a fixed improvement of 1.2 percent for Regional vehicles
including motor coaches and RV's (the same as for tractors and
trailers) and 1.1 percent for Multipurpose, Urban, and other custom
chassis vocational vehicles, recognizing that the higher amount of idle
is likely to reduce the effectiveness for these vehicles. These values
will be specified as GEM inputs in the column designated for tire
pressure systems. See discussion in Section III.D.1.b for our reasoning
behind this effectiveness value.
(viii) HFC Refrigerant From Cabin Air Conditioning (A/C) Systems
    Manufacturers can reduce direct A/C leakage emissions by utilizing
leak-tight components. EPA's HFC direct emission leakage standard is
independent of the CO2 vehicle standard. Manufacturers may
choose components from a menu of leak-reducing technologies sufficient
to comply with the standard, as opposed to using a test to measure
performance. See 76 FR 57194. A discussion of comments regarding use of
low global warming potential refrigerants and EPA's responses to those
comments can be found in Section I.F of this Preamble.
    In Phase 1, EPA adopted a HFC leakage standard to assure that high-
quality, low-leakage components are used in each air conditioning
system installed in HD pickup trucks, vans, and combination tractors
(see 40 CFR 1037.115). We did not adopt a HFC leakage standard in Phase
1 for systems installed in vocational vehicles. In the final Phase 2
program, as proposed, EPA is extending the HFC leakage standard to all
vocational vehicles. Beginning in the 2021 model year, vocational
vehicle air conditioning systems with a refrigerant capacity of greater
than 733 grams must meet a leakage rate of 1.50 percent leakage per
year and systems with a refrigerant capacity of 733 grams or lower meet
a leakage standard of 11.0 grams per year. EPA has determined that an
approach of having a leak rate standard for lower capacity systems and
a percent leakage per year standard for higher capacity systems will
result in reduced refrigerant emissions from all air conditioning
systems, while still allowing manufacturers the ability to produce low-
leak, lower capacity systems in vehicles which require them.
    Research has demonstrated that reducing A/C system leakage is both
highly cost-effective and technologically feasible. The availability of
low leakage components is being driven by the air conditioning program
in the light-duty GHG rule which began in the 2012 model year and the
HD Phase 1 rule that began in the 2014 model year. The cooperative
industry and government Improved Mobile Air Conditioning program has
demonstrated that new-vehicle leakage emissions can be reduced by 50
percent by reducing the number and improving the quality of the
components, fittings, seals, and hoses of the A/C system.\431\ All of
these technologies are already in commercial use and exist on some of
today's systems, and EPA does not anticipate any significant
improvements in sealing technologies for model years beyond 2021.
However, EPA has recognized some manufacturers utilize an improved
manufacturing process for air conditioning systems, where a helium leak
test is performed on 100 percent of all o-ring fittings and connections
after final assembly. By leak testing each fitting, the manufacturer or
supplier is verifying the o-ring is not damaged during assembly (which
is the primary source of leakage from o-ring fittings), and when
calculating the yearly leak rate for a system, EPA will allow a
relative emission value equivalent to a `seal washer' to be used in
place of the value normally used for an o-ring fitting, when 100
percent helium leak testing is performed on those fittings.
---------------------------------------------------------------------------

    \431\ Team 1-Refrigerant Leakage Reduction: Final Report to
Sponsors, SAE, 2007.
---------------------------------------------------------------------------

    We received comments from CARB and Daimler in support of applying
these leakage standards to vocational vehicles. Daimler specifically
expressed support for excluding A/C systems used to cool the cargo area
of trucks, as well as for allowing helium testing as a compliance
option. Thus, we are adopting these provisions as proposed. EMA
commented with concerns about the burden of certifying A/C systems that
are installed by secondary manufacturers. Section V.D.2 discusses how
we have addressed the concerns related to secondary manufacturers. We
also received comments from RVIA asking for clarification whether the
cargo area exclusion also applied to A/C units that cool the living
space of recreational vehicles. In response, we are adding clarifying
language to the regulations at 40 CFR 1037.115 excluding A/C systems
that are not powered by the vehicle's propulsion engine.
    The A/C system leakage control costs presented in the RIA Chapter
2.9 and 2.11 are applied to all heavy-duty vocational vehicles. EPA
views these costs as minimal and the reductions of potent GHGs to be
easily feasible and reasonable in the lead times provided by the final
rules.
(b) Engine Technologies Considered in Vehicle Standard-Setting
    Section II explains the technical basis for the agencies' proposed
separate engine standards. The agencies are not predicating the
vocational vehicle standards on different diesel engine technology
packages than those presumed for compliance with the separate diesel
engine standards. However, for each model year of the Phase 2
standards, the agencies are predicating the SI-powered vocational
vehicle standards on a gasoline engine technology package that includes
additional technologies beyond those presumed for compliance with the
MY 2016 gasoline engine standard. Put another way, the stringency of
certain of the vocational vehicle standards, and those for vehicles
using SI engines in particular, reflect in part improvements in engine
efficiency which are not measured in the engine standard or in engine
certification.
    The primary vocational vehicle standards vary depending on whether
the engines powering those vehicles are compression-ignition or spark-
ignition.\432\ As in Phase 1, this is not the case for the custom
chassis standards, because GEM uses a default engine that is the same
for every regulated custom chassis type, regardless of the actual
engine being installed. As described above in Section II, the Phase 2
vehicle certification tool, GEM, requires manufacturers certifying to
the primary standards to enter specific engine performance data, where
emissions and

fuel consumption profiles will differ significantly depending on the
engine's architecture.\433\
---------------------------------------------------------------------------

    \432\ Specifically, EPA is adopting CO2,
N2O, and CH4 emission standards for new heavy-
duty engines over an EPA specified useful life period (See Section
II).
    \433\ See Section II.D.5 for an explanation of which engine
architecture will need to meet which standard.
---------------------------------------------------------------------------

    As explained in Section II.A.2, engines will continue to be
certified over the FTP test cycle via direct testing, not GEM
simulation. The FTP test cycle that is applicable for bare vocational
engines is very different than the test cycles for vocational vehicles
in GEM. The FTP is a very demanding transient cycle that exercises the
engine over its full range of capabilities. In contrast, the cycles
evaluated by GEM measure emissions over more frequently used engine
operating ranges. The ARB Transient vehicle cycle represents city
driving, and the highway cruise cycles measure engine operation that is
closer to steady state. Each of these cycles is described in the RIA
Chapter 3.4.2. A consequence of recognizing engine performance at the
vehicle level is that further engine improvements (i.e. improvements
measureable by duty cycles that more precisely represent driving
patterns for specific subcategories of vocational vehicles) can be
evaluated as components of a technical basis for a vocational vehicle
standard.\434\ For this reason, the agencies considered whether any
different engine technologies should be included in the feasibility
analysis for the vehicle standards (and potentially, in the standard
stringency).
---------------------------------------------------------------------------

    \434\ As noted in Section II.B.2 above, manufacturers also have
greater flexibility to meet a vehicle standard if engine
improvements can be evaluated as part of compliance testing.
---------------------------------------------------------------------------

    We did not propose to predicate any diesel vocational vehicle
standard on additional engine technology, including engine waste heat
recovery (WHR). We do not believe this technology would show
significant benefit in vocational vehicle applications due to their
driving cycles, which have fewer highway miles than tractors. Thus, the
final vocational vehicle standards assume that diesel engines perform
at the level of the certified engine configuration.
    The agencies received extensive comment on our assessment of SI
engine technologies, and how these could be included in the vocational
vehicle technology packages. We predicated the proposed MY 2027 SI-
powered vocational vehicle standards on additional friction reduction,
for a 0.6 percent fuel efficiency improvement. UCS, EDF, NRDC, and ICCT
ask the agencies to rely on the 2015 SwRI study suggesting 8 percent
improvement is possible. UCS highlights packages #16 and #22 of the
SwRI report for the agencies' further consideration. These packages
were assembled by SwRI to simulate the combined performance of engine
technologies over some well-known vehicle drive cycles. Because none of
the technical data referenced by these commenters provides information
on how these technologies perform over the HD gasoline engine FTP test
procedure, the agencies are considering these to be comments on the
GEM-based vocational vehicle standards, not comments on the separate
FTP-based SI engine standard. Please see Section II.D.2(b) of this
Preamble for the agencies' response to comments on the stringency of
the separate SI engine standard.
    SwRI package #16 applies variable valve actuation and exhaust gas
recirculation to a 3.5 liter V6 engine. SwRI package #22 applies
stoichiometric direct gas injection, exhaust gas recirculation, dual
cam phasers, and advanced friction reduction to a 6.2 liter V8 engine.
All of the SwRI packages compare the future vehicle performance to a
pre-Phase 1 baseline, thus counting all the improvements already
presumed in the MY 2016 engine standard, so the delta between what the
commenter seeks and what the agencies proposed is considerably less
than initially appears (and than the commenter appeared to believe).
The agencies' default SI engine map for setting the SI-powered
vocational vehicle standards is a MY 2016 6.8 liter V8 engine. The RIA
Chapter 2.9.1 presents the EPA default map that meets the MY 2016
engine standard. We are adhering to the proposed approach of
recognizing SI engine improvements only in the vocational vehicle
standard. In response to comments, the agencies are adopting final
vehicle-level standards for SI-powered vocational vehicles that are
predicated in part on adoption of cylinder deactivation in addition to
the advanced friction reduction reflected in the proposal, both of
which have incremental costs beyond those needed to meet the separate
FTP-based engine standard, and both of which will be recognized over
the GEM vehicle cycles. Indeed, cylinder deactivation would not be
expected to be recognized at all over the engine FTP cycle (another
reason the improvement is reflected in the final vehicle standard). As
proposed, the effectiveness and adoption rate of Level 2 engine
friction reduction yields a fuel efficiency improvement of 0.6 percent.
By adding 30 percent adoption of cylinder deactivation with a vehicle-
cycle average effectiveness of 1 percent, and accounting for a dis-
synergy factor of 0.9, this yields an overall package effectiveness of
0.8 percent. Upon consideration of comments and the data in the SwRI
reports, we are not including EGR as a technology for stringency
purposes. EGR is potentially feasible, is not already presumed to be
adopted in the 2016 engine standard, and may possibly be recognized
over the GEM vehicle cycles to some extent. However, we did not have
sufficient data to confidently project an effectiveness or adoption
rate for this technology on vocational SI engines. Further, the Phase 2
HD pickup truck and van standards are not predicated on any adoption of
EGR technologies for SI vehicles. The RIA Chapter 2.9.1 describes how
each of the SI engine technologies are expected to perform over the GEM
vehicle cycles, as well as the method for projecting that the fuel
efficiency improvement will be 0.8 percent compared to the baseline SI
vehicle performance.
    With respect to standards for engines used in custom chassis, we
understand that engines designed for heavy-duty emergency vehicles are
generally higher-emitting than other engines. However, because we are
maintaining a separate engine standard and regulatory flexibility such
as ABT, fire apparatus manufacturers will be able to obtain engines
that, on average, meet the Phase 2 engine standards. The agencies
further recognize that the engine map inputs to GEM in the primary
program could pose a difficulty for emergency vehicle manufacturers. If
we required engine-specific inputs then these manufacturers will have
to apply extra vehicle technologies to compensate for the necessary but
higher-emitting engine. The agencies are therefore not recognizing
vehicle-specific engine performance as part of the vehicle standard for
emergency vehicles (although the standards for emergency vehicles and
custom chassis do presume use of a certified Phase 2 engine).
Manufacturers of these vehicles must install an engine that is
certified to the applicable separate Phase 2 engine standard. However,
under the custom chassis program emergency vehicle manufacturers need
not follow the otherwise applicable Phase 2 approach of entering an
engine map in GEM. Instead, use of a custom chassis subcategory
identifier will instruct GEM to simulate the vehicle using an EPA
default engine.

(c) Technologies the Agencies Assessed But Did Not Use In Standard-
Setting
(i) Aerodynamics
    The agencies did not propose to include aerodynamic improvements as
a basis for the Phase 2 vocational vehicle standards. However, we did
request comment on an option to allow credits for use of aerodynamic
devices such as fairings on a very limited basis. We received public
comments from AAPC in support of offering this as an optional credit,
with a suggestion to allow this option for a wide range of vehicle
sizes, and suggesting that the grams per ton-mile benefit could be
scaled down for larger vehicles. CARB commented in support of a Phase 2
program that would include use of aerodynamic improvements as a basis
for the stringency, suggesting that a large fraction of the vocational
vehicle fleet could see real world benefits from use of aerodynamic
devices. Because we do not have sufficient fleet information to
establish a projected application rate for this technology, we are not
basing any of the final standards for vocational vehicles on use of
aerodynamic improvements. See 80 FR 40303. In consideration of
comments, however, we are adopting provisions for vocational vehicles
to optionally receive an improved GEM result by certifying use of a
pre-approved aerodynamic device, and are expanding eligibility criteria
from the relatively narrow criteria proposed.
    Based on testing supported by CARB, the agencies have developed a
list of specific aerodynamic devices with pre-defined improvement
values (in delta CDA units), as well as criteria regarding
which vehicles are eligible to earn credit in this manner. See Chapter
<IP_ADDRESS> of the RIA. In response to comments, we are allowing a wide
range of vehicles to be eligible to use this option. Regional
vocational vehicles in any weight class may use this option, subject to
restrictions on the size of the chassis (see 40 CFR 1037.520). The
degree of change in CDA for each pre-approved device has
been set at conservative values due to the small number of
configurations tested and the uncertainty inherent in those results.
Manufacturers wishing to receive credit for other aerodynamic
technologies or on other vehicle configurations may seek credit using
the test procedures described in 40 CFR 1037.527. Manufacturers using
this credit provision may enter the pre-defined delta CDA as
an input to GEM, and the simulation will determine the effectiveness
over the duty cycle. Using this approach, we do not need to set a
scaled benefit for different sizes of vehicles. When the vehicle weight
class and duty cycle is specified, a default chassis mass and payload
are simulated in GEM. When the pre-defined delta CDA is
entered, the simulation returns a resulting improved performance with
respect to the specified chassis configuration. GEM will logically
return a smaller improvement for heavier vehicles.
    The final Regional composite duty cycle in GEM for vocational
vehicles has a weighted average speed of 38 mph, increased from the
average speed at proposal due to a heftier 56 percent composite
weighting of the 65 mph drive cycle. The agencies have learned from the
NREL duty cycle analysis that vocational vehicles with operational
behavior of a regional nature accumulate more miles at highway speeds
than previously assumed.
    Using GEM simulation results, the agencies estimate the fuel
efficiency benefit of improving the CDA of a Class 6 box
truck by 11 percent (0.6 m\2\ delta CDA off of a default of
5.4 m\2\) at approximately five percent over the Regional composite
test cycle. This same delta CDA simulated in GEM on a class
8 Regional vocational vehicle results in an overall improvement of less
than four percent because the default CDA in GEM for class 8
vocational vehicles is 6.86 m\2\ so the change in CDA is
only nine percent. Although in actual operation the added weight of
aerodynamic fairings may reduce the operational benefits of these
technologies when driving at low speeds, the agencies are not applying
any weight penalty as part of the certification process for vocational
aerodynamic devices.
    As described in the NPRM, we are requiring chassis manufacturers
employing this option to provide assurances to the agencies that these
devices will be installed as part of the certified configuration, even
if the installation is completed by another entity. We received many
comments on the requirements for secondary manufacturers as they apply
for vocational aerodynamics as well as other technologies that may be
specified by a chassis manufacturer but installed later. See Section
I.F.2 and Section V.D.2 for further discussion of delegated assembly
issues.
(ii) Full Electric Trucks
    Given the high up-front costs and the developing nature of this
technology, the agencies do not project fully electric vocational
vehicles to be widely commercially available in the time frame of the
final rules. For this reason, the agencies have not based the Phase 2
standards on adoption of full-electric vocational vehicles. We received
many comments on electric trucks and buses. Specifically, EEI provided
information on the total cost of ownership for electric trucks, and
some applications may see attractive long term cost scenarios for
electric trucks or buses, when considering maintenance savings. While
we are not predicating the final vocational vehicle standards on
adoption of full electric trucks or buses, we have reinstated an
advanced technology credit multiplier, in response to comment. See
Section I.C.1.(b) for a discussion of credit multipliers.
    To the extent this technology is able to be brought to market in
the time frame of the Phase 2 program, there is currently a
certification path for these chassis from Phase 1, as described in
EPA's regulations at 40 CFR 1037.150 and NHTSA's regulations at 49 CFR
535.8.
(iii) E-PTO
    Although the primary program does not simulate vocational vehicles
over a test cycle that includes PTO operation, the agencies are
adopting a revised hybrid-PTO test procedure. See 76 FR 57247 and 40
CFR 1037.540. Recall that we regulate vocational vehicles at the
incomplete stage when a chassis manufacturer may not know at the time
of certification whether a PTO will be installed or how the vehicle
will be used. Chassis manufacturers may rarely know whether the PTO-
enabled vehicle will use this capability to maneuver a lift gate on a
delivery vehicle, to operate a utility boom, or merely to keep it as a
reserve item to add value in the secondary market. For these reasons,
it would not be fair to require every vocational vehicle to certify to
a standard test procedure with a PTO cycle in it. Thus, we are not
basing the final standards on use of technology that reduces emissions
in PTO mode.
    There are products available today that can provide auxiliary
power, usually electric, to a vehicle that needs to work in PTO mode
for an extended time, to avoid idling the main engine. There are
different designs of electrified PTO systems on the market today. Some
designs have auxiliary power sources, typically batteries, with
sufficient energy storage to power an onboard tool or device for a
short period of time, and are intended to be recharged during the
workday by operating the main engine, either while driving between work
sites, or by idling the engine until a sufficient state of charge is
reached that the engine may shut off. Other designs have

sufficient energy storage to power an onboard tool or device for many
hours, and are intended to be recharged as a plug-in hybrid at a home
garage. In cases where a manufacturer can certify that a PTO with an
idle-reduction technology will be installed either by the chassis
manufacturer or by a second stage manufacturer, the hybrid-PTO test
cycle may be utilized by the certifying manufacturer to measure an
improvement factor over the GEM duty cycle that otherwise applies to
that vehicle. In addition, the delegated assembly provisions will apply
(see Section V.D). See RIA Chapter 3.7.4 for a discussion of the
revisions to the PTO test cycle.
    The agencies will continue the hybrid-PTO test option that was
available in Phase 1, with a few revisions. See the regulations at 40
CFR 1037.540. The calculations recognize fuel savings over a portion of
the test that is determined to be charge-sustaining as well as a
portion that is determined to be charge-depleting for systems that are
designed to power a work truck during the day and return to the garage
where recharging from an external source occurs during off-hours. The
agencies requested comment on this idea, and received comment from
Odyne relating to the population and energy storage capacity of plug-in
e-PTO systems, for which a charge-depleting test cycle may be more
appropriate. We also partnered with DOE-NREL to characterize the PTO
operation of over 80 trucks with over 1,500 total operating days, and
our final regulations include a utility factor table based on these
data for use in determining the effectiveness of a hybrid PTO
system.\435\ Manufacturers wishing to conduct testing as specified may
apply for off-cycle credits derived from e-PTO or hybrid PTO
technologies.
---------------------------------------------------------------------------

    \435\ National Renewable Energy Laboratory July 2016,
``Characterization of PTO and Idle Behavior for Utility Vehicles,''
NREL/TP-5400-66747.
---------------------------------------------------------------------------

(2) Projected Vehicle Technology Package Effectiveness and Cost
(a) Baseline Vocational Engine and Vehicle Performance
    The baseline vocational vehicle configurations for each of the nine
regulatory subcategories for CI-powered and six SI-powered vehicles are
described in RIA Chapter 2.9.1, as well as the seven baseline custom
chassis configurations. The agencies set the baseline rolling
resistance coefficient for the 2017 vocational vehicle fleet at 7.7 kg/
metric ton, which assumes that 100 percent of tires meet the Phase 1
standard.
    In the agencies' Phase 2 baseline configurations, we need to
specify transmission type, gear number, and gear ratios, as well as
axle ratios and tire sizes because these were all defaults in Phase 1.
Phase 1 GEM modeled all vehicles with a manual transmission, but as
explained elsewhere, the majority of vocational vehicles in today's
U.S. fleet have automatic transmissions. By specifying a mix of manual
and automatic transmissions with different sets of gears in the
baseline, we are not applying technology beyond what is needed to
comply with Phase 1, we are merely defining an appropriate set of
baselines. We do not consider these specifications to represent
technology that improves fuel efficiency beyond Phase 1, it is merely a
better representation of today's fleet than the Phase 1 GEM that had
100 percent default manual transmissions. In the Regional HHD diesel
subcategory, the baseline is a weighted average of two vehicle specs:
95 percent being a 455 hp engine paired with a manual transmission with
ten forward gears, and five percent being a 350 hp engine paired with a
6-speed automatic transmission. The HHD Multipurpose subcategory is a
weighted average of three vehicle specs: 80 percent being a 350 hp
engine paired with a 6-speed automatic transmission, 10 percent being a
455 hp engine paired with a 10-speed manual transmission, and 10
percent being a 350 hp engine paired with a 10-speed manual. The
automatic transmissions specified in the LHD, MHD, and HHD Regional and
Multipurpose subcategories have six forward gears in the baseline,
while automatic transmissions in the Urban subcategories have five
forward gears in the baseline. This is based on market research,
stakeholder outreach, and comments received on the NODA. No vehicle-
level efficiency-improving technology is included in the baseline
vehicles, nor in the agencies' analyses for the no-action reference
case. Specifically, we have assumed zero adoption rates for other types
of transmissions, other numbers of gears, idle reduction, and
technologies other than Phase 1 compliant LRR tires in both the
nominally flat baseline and the dynamic baseline reference cases.
Technology adoption rates for Alternative 1a (nominally flat baseline)
can be found in the RIA Chapter 2.11. Chapter 2.11.8 presents the
adoption rates for tires on vocational vehicles with different levels
of rolling resistance, including the 100 percentadoption rate of tires
with Level 1 CRR in the reference case and in model years preceding
Phase 2. In this manner, we have defined a reference vocational vehicle
fleet that meets the Phase 1 standards and includes reasonable
representations of vocational vehicle technology and configurations.
    The agencies note that the baseline performance derived for the
final rules varies between regulatory subcategories--as noted above,
this is one of the reasons the agencies are adopting multiple
subcategories with discrete standards. The range of performance at
baseline is due to the range of attributes and modeling parameters,
such as transmission characteristics, final drive ratio, and vehicle
weight, which were selected to represent a range of performance across
this diverse segment. The agencies received persuasive comment
regarding the appropriateness of the baseline configurations, and have
made revisions accordingly. For example, we have reduced the LHD
default aerodynamic drag area from 5.4 to 3.4 square meters. We are
confident these adequately represent a reasonable range of vocational
chassis configurations currently manufactured in the US. Details of the
vehicle configurations, including reasons why they are reasonably
included as baseline technologies, are discussed in the RIA Chapter
2.9.2.
    At proposal the agencies adjusted the vocational vehicle GEM
numerical baselines using assumptions about the sales mix in the
vocational fleet before applying the reductions from technologies. 80
FR 40308. In this process, we developed proposed baseline values that
we believed would minimize inappropriate incentives for manufacturers
to certify chassis in an inappropriate subcategory. The proposed
approach included testing each baseline vehicle over all three duty
cycles and applying weighted average adjustments to each GEM output to
create normalized baselines, 80 FR 40308. We received adverse comment
on this approach from many commenters--indeed, no commenter supported
this ``normalization'' approach. The proposed normalization approach
was an attempt to adjust for instances where the agencies' information
on baseline configurations was not fully complete. Most commenters
either opposed or were confused by the proposed normalization process.
As explained in this Section V., the agencies are adopting final
standards for vocational vehicles using the same methodology as for all
the other standards in this rulemaking, and

so are neither normalizing nor equalizing any of the data relating to
either the baseline or the standard. (Equalization is discussed
separately in Section V.C.(2)(d) below.) The agencies have received a
great deal of information from manufacturers since proposal which
rectify weaknesses in our baselines, and make any normalization
unnecessary.\436\ In the final rules we have applied other methods
(chiefly certain equipment-based constraints) to avoid creating
inappropriate incentives for manufacturers to certify chassis in
inappropriate subcategories. The final standards are calculated by
applying improvements as described below in Section V.C.(2)(c) to the
GEM results presented in Table V-17 and Table V-18--the same
methodology as used to develop the other Phase 2 standards.
---------------------------------------------------------------------------

    \436\ See memorandum dated July 2016 titled, ``Summary of
Comments on Vocational Vehicle Baselines,'' see Docket EPA-HQ-OAR-
2014-0827.
---------------------------------------------------------------------------

    Diesel engines used in vocational vehicles can be either Light,
Medium, or Heavy Heavy-duty Diesel engines. The Light Heavy-duty Diesel
engines typically range between 4.7 and 6.7 liters displacement. The
Medium Heavy-duty Diesel engines typically have some overlap in
displacement with the Light Heavy-duty Diesel engines and range between
6.7 and 9.3 liters. The Heavy Heavy-duty Diesel engines typically are
represented by engines between 10.8 and 16 liters. Because of these
differences, the GEM simulation of baseline vocational CI engines
includes four engines--one for LHD, one for MHD, and two for HHD.
Detailed descriptions can be seen in Chapter 4 of the RIA. These four
engine models have been employed in setting the vocational vehicle
baselines, as described in the RIA Chapter 2.9.1.
    The four baseline diesel engines represent fuel consumption
improvements beyond currently available engines to achieve the
performance level of a 2017 model year diesel engine, as described in
the RIA Chapter 2.9.1. Using the values for compression-ignition
engines, the baseline performance of vocational vehicles is shown in
Table V-17.

                       Table V-17--Baseline Vocational Vehicle Performance With CI Engines
----------------------------------------------------------------------------------------------------------------
                                                                   Light  heavy-  Medium  heavy-
                           Duty cycle                             duty  Class 2b- duty  Class 6-   Heavy  heavy-
                                                                         5               7         duty  Class 8
----------------------------------------------------------------------------------------------------------------
                            Baseline Emissions Performance in CO[ihel2] gram/ton-mile
----------------------------------------------------------------------------------------------------------------
Urban...........................................................             482             332             338
Multi-Purpose...................................................             420             294             287
Regional........................................................             334             249             220
----------------------------------------------------------------------------------------------------------------
                        Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile
----------------------------------------------------------------------------------------------------------------
Urban...........................................................         47.3477         32.6130         33.2024
Multi-Purpose...................................................         41.2574         28.8802         28.1925
Regional........................................................         32.8094         24.4597         21.6110
----------------------------------------------------------------------------------------------------------------

    The agencies have developed a model in GEM of a MY 2016-compliant
gasoline engine. The agencies received comments on the process for
mapping gasoline engines for simulation purposes, as well as
information about the power rating and displacement that should be
considered as a baseline SI engine for vocational vehicle standard-
setting purposes. Upon consideration of comments, and based on
information obtained through testing at Southwest Research (see Chapter
5.5 of the SwRI report), we are adopting revised test procedures as
described in the RIA Chapter 3.1 that apply for mapping of both SI and
CI engines.\437\
---------------------------------------------------------------------------

    \437\ Michael Ross, Validation Testing for Phase 2 Greenhouse
Gas Test Procedures and the Greenhouse Gas Emission Model (GEM) for
Medium and Heavy-Duty Engines and Powertrains, Final Report to EPA,
Southwest Research Institute, June 2016.
---------------------------------------------------------------------------

    The baseline performance levels for vocational vehicles powered by
SI engines were derived using the EPA default fuel map described in the
RIA Chapter 2.9.1, for a 6.8 liter, V-8, 300 hp engine. We have used
the same engine rating and map for all weight classes of SI vocational
vehicles. This is because SI engines are not certified with a
regulatory structure that calls for declaring an intended service class
that is associated with a vehicle weight class. The agencies requested
comments on the merits of setting distinct numerical standards for HHD
vocational vehicles powered by SI engines, as well as comments on an
alternative approach that would have required any class 8 SI vocational
vehicles to certify to the standards for CI powered HHD vocational
vehicles, or to the MHD standards for SI vocational vehicles. In
response to comments expressing concern about orphaned vehicles as well
as concerns about mismatched engine and vehicle useful life, the
agencies are not finalizing distinct HHD SI vocational vehicle
standards. We are finalizing six subcategories for SI vocational
vehicles: Three LHD and three MHD. Where a manufacturer wishes to
certify a gasoline SI vocational vehicle with a GVWR over 33,000 lbs,
the final regulations allow that vehicle to be certified in one of the
MHD vehicle subcategories. Where a manufacturer wishes to certify an
alternative-fueled vocational vehicle with a GVWR over 33,000 lbs, the
regulations at 40 CFR 1036.108 specify whether that vehicle should be
treated as SI or CI for purposes of certification to the final Phase 2
standards. See Section II.D.5 of this Preamble for a discussion of
these provisions.
    Table V-18 presents the baseline performance level for each weight
class computed by GEM by calculating the work done by the default
engine to move the GEM reference vehicles over the test cycles.

   Table V-18--Baseline Vocational Vehicle Performance With SI Engines
------------------------------------------------------------------------
                                                         Medium  heavy-
                                    Light  heavy-duty   duty  Class 6-7
            Duty cycle                  Class 2b-5       (and  Gasoline
                                                            c8) \a\
------------------------------------------------------------------------
        Baseline Emissions Performance in CO[ihel2] gram/ton-mile
------------------------------------------------------------------------
Urban.............................                502                354
Multi-Purpose.....................                441                314
Regional..........................                357                275
------------------------------------------------------------------------
    Baseline Fuel Efficiency Performance in gallon per 1,000 ton-mile
------------------------------------------------------------------------
Urban.............................            56.4870            39.8335
Multi-Purpose.....................            49.6230            35.3325
Regional..........................            40.1710            30.9441
------------------------------------------------------------------------
Note:
\a\ Vocational vehicles with GVWR over 33,000 lbs powered by alternate
  fueled engines must certify to the vehicle standard corresponding with
  the applicable engine standard.

(b) Technology Packages for Derivation of Final Standards
    Prior to developing the numerical values for the final standards,
the agencies projected the mix of new technologies and technology
improvements that will be feasible within the available lead time. We
note that for some technologies, the adoption rates and effectiveness
may be very similar across subcategories. However, for other
technologies, either the adoption rate, effectiveness, or both differ
across subcategories. Where a technology performs differently over
different test cycles, these differences are reflected in the
derivation of the stringency of the standard. As discussed in Section
I.C.1, we assume manufacturers will incorporate appropriate compliance
margins for all measured GEM inputs. In other words, they will declare
values slightly higher than their measured values. As discussed in
Section II.D.5, compliance margins associated with fuel maps are likely
to be approximately one percent. For tire rolling resistance, our
feasibility rests on the Phase 1 standards, consistent with our
expectation that manufacturers will continue to incorporate the
compliance margins they considered necessary for Phase 1. With respect
to optional axle and/or transmission power loss maps, we believe
manufacturers will need very small compliance margins. These power loss
procedures require high precision so measurement uncertainty will
likely be on the order of 0.1 percent of the transmitted power. All of
these margins are reflected in our projections of the emission levels
that will be technologically feasible, as well as the associated costs.
    In the package descriptions that follow, individual technology
costs are not presented, rather these can be found in the RIA Chapter
2.9 and 2.11. Section V.C.(2)(d) includes the costs estimated for
packages of technologies the agencies project can be applied to
vocational vehicles to meet the final Phase 2 standards.
(i) Transmission Packages
    The agencies project an adoption rate of 50 percent in MY 2021, 60
percent in MY 2024, and nearly 70 percent in MY 2027 of transmissions
with improved gear efficiencies, with inputs over-riding the GEM
defaults obtained over the separate transmission efficiency test. We
are projecting an adoption rate of 10 percent in MY 2021, 20 percent in
MY 2024, and nearly 30 percent in MY 2027 of advanced shift strategies,
with demonstration of improvements recognized over the separate
powertrain test.
    We are predicating the Phase 2 standards on zero adoption of added
gears in the HHD Regional subcategory, because it is modeled with a 10-
speed transmission, and vehicles already using that number of gears are
not expected to see any real world improvement by increasing the number
of available gears. For the Multipurpose and Urban HHD subcategories,
the MY 2021 projected adoption of adding gears is 5 percent, increasing
to 10 percent for MY 2024 and MY 2027. We are projecting 10 percent of
adding two gears in each of the other six subcategories for MY 2021,
increasing to 20 percent for MY 2024 and MY 2027. Commenters supported
the inclusion of this technology as part of the basis for the
standards. Allison commented that they have configured an 8-speed
vocational transmission. Eaton's new MHD dual clutch transmission has
seven forward gears. There is also a likelihood that suppliers of 8-
speed transmissions for HD pickups and vans may sell some into the LHD
vocational vehicle market.
    We are also predicating the optional custom chassis standards for
school and coach buses in part on adoption of transmissions with
additional gears. In MY 2021, this adoption rate is five percent,
increasing to 10 percent in MY 2024 and 15 percent in MY 2027.
Manufacturers who certify these vehicles to the primary standards will
use GEM to model the actual gears and gear ratios; however,
manufacturers using custom chassis regulatory subcategory identifiers
will not have this flexibility. The agencies have estimated the cycle-
average benefit of adding an extra gear for school buses (modeled as
MHD Urban vehicles) at 0.9 percent and coach buses (with 6 gears in the
baseline) at 1.7 percent; therefore, manufacturers using custom chassis
regulatory subcategory identifiers for these vehicles will be permitted
to enter these pre-defined improvement values at the time of
certification.
    Based on comment regarding our regulatory baselines, both the HHD
Regional and HHD Multipurpose subcategories now have manual
transmissions in the baseline configuration. For these vehicles, the
agencies project upgrades to automated transmissions such as either
AMT, DCT, or automatic, at an adoption rate of 30 percent in MY 2021,
50 percent in MY 2024, and 80 percent in MY 2027 for Regional vehicles.
For Multipurpose, beginning with 20 percent manuals in the baseline,
the adoption rate of automated transmissions is five percent in MY 2021
and 20 percent in MY 2024. Consistent with our projections of
technology adoption, the regulations require that any vocational
vehicles with manual transmissions must be certified as Regional in MY
2024 and beyond. This progression of

transmission automation is consistent with the agencies' projection of
10 percent manuals and 90 percent automated transmissions in the day
cab tractor subcategories in MY 2027. See Table III-13. HHD vocational
vehicles in regional service have many things in common with day cab
tractors, including the same assumed engine size and typical
transmission type, and a similar duty cycle. Thus, it is reasonable for
the agencies to make similar projections about the fraction of
automated vs manual transmissions adopted over the next decade among
these sectors. Also consistent with tractors, GEM simulates each of
these with a two percent fixed effectiveness improvement over the
performance of the MT in the baseline. To the extent any of these
transmissions provide additional effectiveness over the GEM cycles with
actual OEM data entered, it is not considered in the stringency of the
vocational vehicle HHD Regional standard (but would be recognized at
certification). The agencies have been unable to characterize the
relative effectiveness of DCT compared with AT sufficiently to apply it
as a technology on which stringency is predicated. This is consistent
with the public comment on this issue: Daimler did not support
inclusion of DCT as a technology with different effectiveness than AMT,
and Allison did not support treatment of either DCT or AMT as different
as AT.
    In the seven subcategories (i.e. all of the remaining
subcategories) in which automatic transmissions are the base
technology, the agencies project that ten percent of the HHD vehicles
will apply an aggressive torque converter lockup strategy in MY 2021,
and 30 percent in the LHD and MHD subcategories. These adoption rates
are projected to increase to 20 percent for HHD and 40 percent for LHD
and MHD in MY 2024. We project adoption of aggressive torque converter
lockup for HHD automatics of 30 percent in MY 2027, and 50 percent for
LHD and MHD.
    In setting the standard stringency, we have projected that non-
integrated (bolt-on) mild hybrids will not have the function to turn
off the engine at stop, while the integrated mild hybrids will have
this function. The agencies have estimated the effectiveness for
vehicles certified in the Urban subcategories will achieve as much as
13 percent improvement, and integrated systems that turn off at stop
will see up to 21 percent improvement depending on the subcategory. We
have also projected zero hybrid adoption rate (mild or otherwise) by
vehicles in the Regional subcategories, expecting that the benefit of
hybrids for those vehicles will be too low to merit use of that type of
technology. However, there is no fixed hybrid value assigned in GEM
and, for any vehicles utilizing hybrid technology, the actual
improvement over the applicable test cycle will be determined by
powertrain testing, which would likely reflect some benefit of hybrids
on Regional vehicles. By the full implementation year of MY 2027, the
agencies are projecting an overall vocational vehicle adoption rate of
12 percent mild hybrids, which we estimate will be 14 percent of
vehicles certified in the Multi-Purpose and Urban subcategories (six
percent integrated and eight percent non-integrated). We are projecting
a low adoption rate in the early years of the Phase 2 program, zero
integrated hybrid systems and two percent of the bolt-on systems in
these subcategories in MY 2021, and three percent integrated mild
hybrids in MY 2024 for vehicles certified in the Multi-Purpose and
Urban subcategories, plus 5 percent non-integrated mild hybrids in MY
2024. Based on our assumptions about the populations of vehicles in
different subcategories, these hybrid adoption rates are about two
percent overall in MY 2021 and six percent overall in MY 2024.
    Navistar commented with concerns that the agencies may be double
counting some of the improvements of deep integration. For example, the
addition of a gear to a transmission may reduce the added benefit of
deep integration, as the transmission may already achieve a more
optimal operation state more often due to the greater number of gears.
The agencies have been careful to project adoption rates and
effectiveness of transmission technologies in a way that that avoids
over-estimating the achievable reductions. For example, as we developed
the packages, we reduced the adoption rate of advanced shift strategy
by the adoption rate of integrated hybrids, and we reduced the adoption
rate of transmission gear efficiency by the amount of non-integrated
hybrids. This is because we do not project that any driveline will
undergo testing over both the powertrain test and the separate
transmission efficiency test. Because we have projected adoption of
combinations of transmission technologies in some subcategories, the
sum of adoption rates of individual transmission technologies may
exceed 100 percent in some cases. However, the effectiveness values
have not been summed because we agree with the commenter that we should
not double count benefits. Instead of summing the combined
efficiencies, we combine multiplicatively as described in Equation V-1,
below. Thus, we have fairly accounted for dis-synergies of
effectiveness where multiple technologies are applied to a similar
vehicle system.
    Custom chassis manufacturers have provided compelling comment that
the absence of recognition in the certification process of improved
transmission technology will not deter them from its adoption.
Therefore, although some types of improved transmissions are feasible
for some custom chassis, these vehicles are typically assembled from
off-the-shelf parts in low production volumes. For most components,
this is not a significant obstacle. However, this dynamic can limit
their access to the most advanced transmission technologies.
Transmission manufacturers would generally be willing to supply
advanced transmissions they developed for a larger customer, but would
be less likely to invest in developing a special low volume
transmission for the custom chassis. Similar circumstances would apply
for hybrids. Further, for the reasons described above about non-
representative drivelines in the baseline configurations, we believe
that allowing these to be certified with a default driveline is a
reasonable program structure. For school buses and others, if a
manufacturer wishes to be recognized beyond the levels described for
adopting improved transmissions, it has the option of certifying to the
primary standards. Nevertheless, technology improvements that some of
these manufacturers will include based on market forces (after they
have been introduced into the market as a result of the primary
program) will likely result in actual in-use improvements for many
these vehicles beyond what is projected by the standards.
(ii) Axle Packages
    The agencies project that 10 percent of vocational vehicles in all
subcategories will adopt high efficiency axles in MY 2021, 20 percent
in MY 2024, and 30 percent in MY 2027. Fuel efficient lubricant
formulations are widespread across the heavy-duty market, though
advanced synthetic formulations are currently less popular.\438\ Axle
lubricants with improved viscosity and efficiency-enhancing performance
are projected to

be widely adopted by manufacturers in the time frame of Phase 2. Such
formulations are commercially available and the agencies see no reason
why they could not be feasible for most vehicles. Nonetheless, we have
refrained from projecting full adoption of this technology. The
agencies do not have specific information regarding reasons why axle
manufacturers may specify a specific type of lubricant over another,
and whether advanced lubricant formulations may not be recommended in
all cases. The agencies received adverse comment on allowing fixed
credit for use of high efficiency axles, whether from lubrication or
other mechanical designs. In response, we are adopting a separate axle
efficiency test, which can be used as an input to GEM to over-ride
default axle efficiency values. The low overall adoption rate indicates
that we expect axle suppliers to only offer high-efficiency axles for
their most high production volume products, especially those that can
serve both the tractor and vocational market. Therefore, we believe it
is unlikely that high-efficiency axles will be adopted in custom
chassis applications. Because we are no longer offering a fixed
improvement for this technology as at proposal, this is only available
for vocational vehicles that are certified to the primary program.
---------------------------------------------------------------------------

    \438\ See meeting log for proposed rule, specifically the April
2014 meeting with Dana. https://www.regulations.gov/document?D=EPA-HQ-OAR-2014-0827-0702
---------------------------------------------------------------------------

    The agencies estimate that 10 percent of HHD Regional vocational
vehicles and five percent of HHD Multipurpose vehicles will adopt part
time 6x2 axle technology in MY 2021. This technology is most likely to
be applied to Class 8 vocational vehicles (with 2 rear axles) that are
designed for frequent highway trips. The agencies project a 20 percent
adoption rate for HHD Regional and 15 percent adoption rate for HHD
Multipurpose for part time 6x2 axle technologies in MY 2024. In MY
2027, we project 30 percent adoption of part time 6x2 for HHD Regional
and 25 percent for HHD Multipurpose. We are establishing a custom
chassis baseline configuration for coach buses with a 6x2 axle, in
consideration of comments from UCS and manufacturers stating this is
the standard axle configuration for these vehicles. If a HHD coach bus
is sold with a 6x4 or part time 6x2 axle, the manufacturer must enter
the as-built axle configuration as a GEM input. This is true whether
the vehicle is in the primary program or if it is certified to the
custom chassis standard. Because the optional custom chassis standard
assumes a 6x2 axle in the coach bus baseline, manufacturers may only
qualify to obtain a reduced GEM result from use of the 300 pound weight
reduction value (specified in 40 CFR 1037.520 associated with use of a
permanent 6x2 axle) when certifying coach buses to the primary
standards.
(iii) Tire Packages
    The agencies estimate that the per-vehicle average level of rolling
resistance from vocational vehicle tires could be reduced by up to 13
percent for many vehicles by full implementation of the Phase 2 program
in MY 2027, based on broader adoption of vocational vehicle tires
currently available. We estimate this will yield reductions in fuel use
and CO2 emissions of up to 3.3 percent for these vehicles.
All of our estimates of vehicle-level tire CRR improvements employ a
weighted average using an assumed axle load distribution of 30 percent
on the steer tires and 70 percent on the drive tires, as was
proposed.\439\ The projected adoption rates of tires with improved CRR
for chassis in the primary program are presented in Table V-19. The
levels noted in the table are defined above in Table V-15. By applying
the assumed axle load distribution, the estimated vehicle CRR
improvement projected as part of the MY 2021 standards ranges from 5 to
8 percent, which we project will achieve up to 1.9 percent reduction in
fuel use and CO2 emissions, depending on the vehicle
subcategory. The agencies estimate the vehicle CRR improvement in MY
2024 will range from 5 to 13 percent, yielding reductions in fuel use
and CO2 emissions up to 3.2 percent, depending on the
vehicle subcategory.
---------------------------------------------------------------------------

    \439\ See Vehicle Valuation Services Quick Reference Guide,
available at. http://www.vvsi.com/training/TrainingGuide.pdf,
(accessed June 2014), the draft RIA at Chapter 2.9.2, and Docket ID
EPA-HQ-OAR-2014-0827-0434.
---------------------------------------------------------------------------

    The agencies believe that these tire packages recognize the variety
of tire purposes and performance levels in the vocational vehicle
market, and maintain choices for manufacturers to use the most
efficient tires (i.e. those with lowest rolling resistance) only where
it makes sense given these vehicles' differing purposes and
applications.

                                                      Table V-19--Projected LRR Tire Adoption Rates
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Regional                              Multipurpose                                Urban
                                 -----------------------------------------------------------------------------------------------------------------------
                                         Steer               Drive               Steer               Drive               Steer               Drive
--------------------------------------------------------------------------------------------------------------------------------------------------------
2021 HHD........................  100% LRR 5v.......  100% LRR 2v.......  100% LRR 5v.......  100% LRR 2v.......  100% LRR 4v.......  100% LRR 1v.
2021 MHD........................  100% LRR 3v.......  100% LRR 1v.......  100% LRR 3v.......  100% LRR 1v.......  100% LRR 3v.......  100% LRR 1v.
2021 LHD........................  100% LRR 3v.......  100% LRR 3v.......  100% LRR 3v.......  100% LRR 3v.......  100% LRR 2v.......  100% LRR 2v.
2024 HHD........................  100% LRR 5v.......  100% LRR 3v.......  100% LRR 5v.......  100% LRR 2v.......  100% LRR 4v.......  100% LRR 1v.
2024 MHD........................  100% LRR 5v.......  100% LRR 3v.......  100% LRR 3v.......  50% LRR 1v, 50%     100% LRR 3v.......  100% LRR 1v.
                                                                                LRR 2v.
2024 LHD........................  100% LRR 5v.......  100% LRR 3v.......  100% LRR 3v.......  100% LRR 3v.......  100% LRR 2v.......  100% LRR 2v.
2027 HHD........................  100% LRR 5v.......  100% LRR 3v.......  100% LRR 5v.......  100% LRR 3v.......  100% LRR 5v.......  100% LRR 2v.
2027 MHD........................  100% LRR 5v.......  100% LRR 3v.......  100% LRR 5v.......  100% LRR 3v.......  100% LRR 3v.......  50% LRR 1v, 50%
                                                                                LRR 2v.
2027 LHD........................  100% LRR 5v.......  100% LRR 3v.......  100% LRR 5v.......  100% LRR 3v.......  100% LRR 3v.......  50% LRR 2v, 50%
                                                                                LRR 3v.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Table V-20 presents the projected adoption rates of LRR tires for
custom chassis. As noted above in Section V.C.(1)(a)(iii), the adoption
rates generally represent improvements in the range of the 25th to 40th
percentile using data from actual vehicles in each application that
were certified in MY 2014. A summary of these data is provided in a
memorandum to the docket.\440\ An exception to this is emergency
vehicles. The final emergency vehicle standards reflect adoption of
tires that progress to the 50th percentile by MY 2027, using steer and
drive tire data for certified emergency vehicles. At these adoption
rates, manufacturers need not change any of the tires they are
currently fitting on emergency vehicles, and they will comply on
average.
---------------------------------------------------------------------------

    \440\ See memorandum on tire data, Note 419, above.

                        Table V-20--Projected LRR Tire Adoption Rates for Custom Chassis
----------------------------------------------------------------------------------------------------------------
                                                  MY 2021                                 MY 2027
                                 -------------------------------------------------------------------------------
                                         Steer               Drive               Steer               Drive
----------------------------------------------------------------------------------------------------------------
Coach...........................  100% LRR 4v.......  100% LRR 4v.......  100% LRR 5v.......  100% LRR 5v.
RV..............................  100% LRR 5v.......  100% LRR 5v.......  100% LRR 5v.......  100% LRR 5v.
School..........................  100% LRR 4v.......  100% LRR 2v.......  100% LRR 5v.......  100% LRR 4v.
Transit.........................  100% LRR 1v.......  100% LRR 1v.......  100% LRR 3v.......  100% LRR 3v.
Refuse..........................  100% LRR 1v.......  100% LRR 1v.......  100% LRR 3v.......  100% LRR 3v.
Mixer...........................  100% LRR 2v.......  100% LRR 1v.......  100% LRR 3v.......  100% LRR 2v.
Emergency.......................  100% LRR 2v.......  100% LRR 1v.......  100% LRR 4v.......  100% LRR 1v.
----------------------------------------------------------------------------------------------------------------

(iv) Idle Reduction Packages
    In these rules, the adoption rate of AES for HHD Regional vehicles
is 40 percent in MY 2021, 80 percent in MY 2024, and 90 percent in MY
2027. This is because these vehicles have driving patterns with a
significant amount of parked idle, and the vast majority have
relatively modest accessory demands such that only a few would have
such large demands for backup power that turning the engine off while
parked would not be feasible. For all weight classes of Regional
vehicles except coach buses, the neutral idle and stop start adoption
rates remain zero in all model years because these vehicles have
driving patterns with such a small amount of transient driving that
this drive-idle technology would not likely provide real world
benefits. For coach buses we are predicating the optional custom
chassis standard in part on adoption of neutral idle for several
reasons. First, according to Volvo, we are underestimating the amount
of transient time for these vehicles by applying only a 20 percent
weighting of the transient cycle instead of 25 percent as noted in
their comment. Second, we estimate that neutral idle is a low cost
technology that would easily pay for itself with the miles accumulated
by coach buses. Finally, in the custom chassis program manufacturers
are able to qualify for a reduced emission rate in GEM through
selection of neutral idle even if the transmission architecture
inherently functions with neutral idle such as with an AMT or DCT. The
Regional vehicles carry a 40 percent, 80 percent, and 90 percent
adoption rate of AES in MYs 2021, 2024, and 2027 respectively because
these vehicles are not projected to apply any other idle reduction
technology and as long as large accessory loads are not required this
technology is widely feasible. As reflected in the Multipurpose and
Urban duty cycles with an overall composite test weighting of zero
speed operation of 50 percent with 25 percent composite weighting of
the parked idle cycle, idle reduction is a significant technology for
these vehicles. We are projecting 30 percent adoption of AES in all
weight classes of Multipurpose and Urban vocational vehicles in MY
2021, increasing to 60 percent in MY 2024 and 70% in MY 2027. This is
less than for Regional because we expect a larger fraction of vehicles
in these subcategories will need to run PTO or other accessories while
parked, such that fewer will be able to reasonably apply the low-cost
AES that we have identified in this rulemaking. Because we are
considering stop-start and neutral idle to be mutually exclusive on a
per-vehicle basis, the sum of these two technologies does not exceed 90
percent in MY 2027, and gradually ramps up to this level from the 50 to
60 percent range in MY 2021. Neutral idle adoption rates are greater in
the early years because we expect this will not need much lead time, if
any. An exception to the 90 percent maximum adoption rate is transit
buses, where we believe all vehicles of this type can reasonably apply
some form of drive idle reduction technology. The adoption rates of
idle reduction technologies for vocational vehicles in MY 2027 is
presented in Table V-21.

                                            Table V-21--MY 2027 Adoption Rates of Idle Reduction Technologies
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Heavy heavy-duty                      Medium heavy-duty                       Light heavy-duty
                                    --------------------------------------------------------------------------------------------------------------------
             Technology                              Multi-                                 Multi-                                 Multi-
                                       Regional     purpose       Urban       Regional     purpose       Urban       Regional     purpose       Urban
--------------------------------------------------------------------------------------------------------------------------------------------------------
Neutral Idle.......................            0           70           70            0           60           60            0           60           60
Stop-Start.........................            0           20           20            0           30           30            0           30           30
AES................................           90           70           70           90           70           70           90           70           70
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Although it is possible that a vehicle could have both neutral idle
and stop-start, our stringency calculations only consider emissions
reductions where a vehicle either has one or the other of these
technologies. The final GEM input file allows users to apply multiple
idle reduction technologies within a single vehicle configuration.
    Because we have included costs to maintain engine protection during
periods of shut-off, as well as over-rides to recognize instances where
it may not be safe to shut off an engine, we believe stop-start can
safely be applied at the rates described above in the time frames
described. Also, because we have defined two idle cycles where the
automatic engine shutoff technology addresses the condition of being
parked with the brake off, we believe this alleviates many of the
concerns expressed by commenters about stop-start. We believe many
commenters were (erroneously) imagining that stop-start systems would
be required to function during periods of extended parking.
    We agree with commenters that stop-start is not feasible for
emergency vehicles and concrete mixers. We further believe that stop-
start would not provide any real world benefit for coach buses or motor
homes. However, for school buses, transit buses, and refuse trucks, we
believe stop-start is feasible and likely to result in real world
benefits. The only custom chassis standards that we are basing on
adoption of AES is school buses, because for the others, we believe the
simple shutdown timer would be likely to encounter an over-ride
condition frequently enough to yield a very small benefit from this
technology. To make AES practical for a coach or transit bus for
example, a much larger auxiliary power source would be needed than the
one projected as part of this rulemaking. Although many school buses
have voluntarily adopted idle reduction strategies for other reasons,
we do not believe many have tamper-proof automatic shutdown systems.

                             Table V-22--Custom Chassis Workday Idle Adoption Rates
----------------------------------------------------------------------------------------------------------------
                   Technology                           MY              AES             NI          Stop-start
----------------------------------------------------------------------------------------------------------------
Coach...........................................            2021  ..............              40  ..............
                                                            2027  ..............              70  ..............
School..........................................            2021              30              60               5
                                                            2027              70              60              30
Transit.........................................            2021  ..............              60              10
                                                            2027  ..............              70              30
Refuse..........................................            2021  ..............              30               0
                                                            2027  ..............              50              20
----------------------------------------------------------------------------------------------------------------

    As described above, the agencies are excluding refuse trucks that
do not compact waste from the optional custom chassis vocational
vehicle standards. We believe trucks that do not compact waste have
sufficiently low PTO operation (usually only while parked) to make
application of drive idle reduction technologies (and other
technologies projected for regular vocational chassis) quite feasible.
Front-loading refuse collection vehicles tend to have a relatively low
number of stops per day as they tend to collect waste from central
locations such as commercial buildings and apartment complexes. Because
these have a relatively low amount of PTO operation, we expect stop-
start will be reasonably effective for these vehicles. Rear-loading and
side-loading neighborhood waste and recycling collection trucks are the
refuse trucks where the largest number of stop-start and neutral idle
over-ride conditions are likely to be encountered. Because chassis
manufacturers, even those with small production volumes and close
customer relationships, do not always know whether a refuse truck
chassis will be fitted with a body designed for front loading, rear
loading, or side loading, we are applying an adoption rate of 20
percent stop-start in 2027 to refuse trucks certified as custom
chassis. In the case where a chassis manufacturer certifies a refuse
truck to the primary standards under the HHD Urban subcategory, the MY
2027 adoption rate of stop-start is also 20 percent as shown in Table
V-21. The stringency in both cases assumes a sufficiently capable stop-
start system to not require an excessive use of over-rides.
Manufacturers opting to certify refuse trucks to the primary standards
will have an option to be recognized for enhanced stop-start systems
through the powertrain test.
    It may take some minor development effort to apply neutral idle to
high-torque automatic transmissions designed for the largest vocational
vehicles. Based on stakeholder input, the designs needed to avoid an
uncomfortable re-engagement bump when returning to drive from neutral
may require some engineering refinement as well as some work to enable
two-way communication between engines and transmissions. Nonetheless,
this technology should be available in the near term for many vehicles
and is low cost compared to many other technologies we considered.
Commenters asked for over-rides such as when on a steep hill and we
agree and are adopting this provision.
    For the reasons described above, we see the above idle reduction
technologies being technically feasible on the majority of vocational
vehicles. The RIA Chapter <IP_ADDRESS> and RIA Chapter <IP_ADDRESS>.4 provide
additional discussion on workday idle reduction technologies for
vocational vehicles.
(v) Weight Reduction Packages
    As described in the RIA Chapter <IP_ADDRESS>, weight reduction is a
relatively costly technology, at approximately $3 to $10 per pound for
a 200-lb package. Even so, for vehicles in service classes where dense,
heavy loads are frequently carried, weight reduction can translate
directly to additional payload. The agencies project that modest weight
reduction is feasible for all vocational vehicles. The agencies are
predicating the final standards on adoption of weight reduction
comparable to what can be achieved through use of aluminum wheels (an
easy material switch that does not alter load distribution on the
chassis). This package is estimated at 150 pounds for LHD and MHD
vehicles, and 250 pounds for HHD vehicles, based on six and 10 wheels,
respectively. This value is revised upward since proposal based on
compelling comments from the Aluminum Association recommending that we
set the same level of weight reduction for lightweight aluminum alloys
as for regular aluminum, at 25 pounds per wheel. More details on these
comments may be found in the Response to Comments Chapter 5. In MY
2021, we project an adoption rate of 10 percent, 30 percent in MY 2024,
and 50 percent in MY 2027 for all subcategories in the primary program.
    The agencies project manufacturers will have sufficient options of
other components eligible for material substitution so that this level
of weight reduction will be feasible even where aluminum wheels are not
selected by customers. Based on comments, we have removed aluminum
transmission cases and aluminum clutch housings from the vocational
lookup table.
    We are not predicating the custom chassis standards on any use of
weight reduction. We have learned that manufacturers of concrete
mixers, refuse trucks, and some high end buses have already made
extensive use of lightweighting technologies in the baseline fleet. We
also received persuasive comment cautioning us not to base the school
bus standards on weight reduction due to potential conflicts with
safety standards. In considering this information, we are allowing all
vehicles certified using custom chassis regulatory subcategory
identifiers to make use of weight reduction as a compliance
flexibility. We received compelling comment from UCS that weight
reduction should be considered feasible for transit buses. Upon
consideration of this comment as well as information regarding the
preponderance of city buses with overloaded axles, we are predicating
standard stringency for transit buses on use of aluminum wheels at the
same adoption rate as for the primary program. See the RIA at Chapter
<IP_ADDRESS>.5 for more information about transit bus axles.
(vi) Electrified Accessory Packages
    The agencies are predicating the final vocational vehicle standards
in part on an adoption rate of five percent in MY 2021 of an
electrified accessory package that achieves one percent fuel efficiency
improvement. The discussion in Section V.C.(1)(a)(vi) describes some
pre-defined e-accessory improvements that are available in GEM for all
vocational vehicles. In MY 2024 we increase this adoption rate to ten
percent, and in MY

2027 the projected adoption rate is 15 percent, applicable in all
subcategories excluding custom chassis. Although we believe some
components could be electrified for some custom chassis, we do not have
sufficient information to estimate an incremental cost associated with
electrifying the more complex systems on custom chassis such as buses,
or to project a specific adoption rate for this type of improvement.
(vii) Tire Pressure System Packages
    The agencies are predicating the vocational vehicle standards in
part on widespread adoption of tire pressure monitoring systems. These
are readily accepted by fleets as a cost-effective safety and fuel-
saving measure. Because there may be some minor challenges in applying
this technology to some vehicles where the payload and duty cycle lead
to very high tire temperatures and pressures (as described above), we
are applying a lower adoption rate to Urban and Multi-purpose vehicles
than to Regional vehicles, as shown in Table V-23. We are applying
similarly lower adoption rates for refuse trucks and transit buses. We
are not predicating the emergency vehicle or cement mixer standards on
adoption of TPMS.
    We are predicating the optional school bus, coach bus, transit bus,
and refuse truck standards in part on limited adoption of automatic
tire inflation systems (ATIS), as shown in Table V-23. These are more
costly than TPMS, and require an onboard air supply and sometimes
extensive plumbing of air lines.

                           Table V-23--Vocational Tire Pressure System Adoption Rates
----------------------------------------------------------------------------------------------------------------
                                                       TPMS                                    ATIS
           Technology            -------------------------------------------------------------------------------
                                      MY 2021         MY 2024         MY 2027         MY 2021         MY 2027
----------------------------------------------------------------------------------------------------------------
Regional........................              60              75              90  ..............  ..............
Multi-Purpose...................              50              65              80  ..............  ..............
Urban...........................              40              55              70  ..............  ..............
School..........................              70  ..............              80  ..............              20
Coach...........................              50  ..............              75              10              25
Transit.........................              40  ..............              50              10              20
Refuse..........................              40  ..............              50              10              15
Motor Home......................              60  ..............              90  ..............  ..............
----------------------------------------------------------------------------------------------------------------

(c) GEM Inputs for Derivation of Vocational Vehicle Standards
    To account for engine-level improvements consistent with those
projected to meet Phase 2 vocational engine standards, and which will
be reflected over the GEM vehicle test cycles, the agencies developed a
suite of fuel consumption maps for use with the GEM: One set of maps
that represent engines meeting the MY 2021 vocational diesel engine
standards, a second set of maps representing engines meeting the MY
2024 vocational diesel engine standards, and a third set of maps
representing engines meeting the MY 2027 vocational diesel engine
standards.\441\ By incorporating the engine technology packages
projected to be adopted to meet the Phase 2 vocational CI engine
standards, the agencies employed GEM engine models in deriving the
stringency of the Phase 2 CI-powered vocational vehicle standards.
Similarly, to account for the performance of Phase 2 SI engines in
deriving the stringency of the Phase 2 SI-powered vocational vehicle
standards, the agencies employed our baseline SI GEM engine model. The
extra engine technology on which the Phase 2 SI vocational vehicle
standards are based was applied in post-processing the GEM results, not
modeled with an improved GEM map. See the RIA Chapter 2.9.1 for more
details about the vocational engines used in standard-setting.
---------------------------------------------------------------------------

    \441\ See Section II.D.2 of this Preamble for the derivation of
the engine standards.
---------------------------------------------------------------------------

    The derivation of the vocational vehicle standards incorporates
several methods because some GEM inputs lend themselves to fleet-
average values, some are vehicle specific (either on or off) and some
improvements are not directly modeled in GEM. For each model year of
standards, the agencies derived a scenario vehicle for each subcategory
using the future model year engine map with fleet average input values
for tire rolling resistance and weight reduction. For example, the MY
2021 HHD weight reduction input value was derived as follows: 250
pounds times 10 percent adoption yields 25 pounds. Those scenario
vehicle performance results were combined in a post-process method with
subcategory-specific improvements from idle reduction, axle disconnect,
torque converter lockup, and transmission automation, using directly
modeled GEM improvements comparing results with these technologies on
or off the scenario vehicle. Subsequently, these performance values
were combined with estimated improvement values of technologies not
modeled in GEM, including TPMS, hybrids, and transmission gear
efficiency.
    The set of fleet-average inputs for tire CRR and weight reduction
for MY 2021, as modeled in GEM is shown in Table V-24, along with the
respective adoption rates for idle reduction, axle disconnect, and
torque converter lockup. The agencies derived the level of the MY 2024
standards by using the GEM inputs and adoption rates shown in Table V-
25, below. The agencies derived the level of the MY 2027 standards by
using the GEM inputs and adoption rates shown in Table V-26, below.
Post-processing improvements for technologies not directly modeled,
including TPMS, e-accessories, hybrids, and axle and transmission
improvements are presented as a combined driveline improvement factor
in Table V-27, below. The values in this table for SI-powered
vocational vehicles include improvements due to adoption of SI engine
technology. The methodology for estimating these improvements is
described in the RIA Chapter 2.9.1. The final standards are presented
in Table V-4 through Table V-9.

                                    Table V-24--GEM Inputs Used To Derive Final MY 2021 Vocational Vehicle Standards
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                   Class 2B-5                                                  Class 6-7                            Class 8
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Multi-                              Multi-                              Multi-
                          Urban                             purpose    Regional      Urban      purpose    Regional      Urban      purpose    Regional
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      SI Engine
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                             2018 MY 6.8L, 300 hp engine