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6 Review of Options to Reduce Energy Use of Trailers This chapter addresses the opportunities to reduce the energy consumed by Class 8 tractors pulling, particularly, van trailers. Following some background information, three government programs that deal with tractor-trailer fuel consumption are summarized. Next, the technologies associated with tractor and trailer aerodynamics as well as tires for both components are discussed. The contribution to life-cycle tire costs of pressure monitoring (and maintenance) systems (TPMS) and greenhouse gas (GHG) emissions will also be considered. Finally, the findings and appropriate recommendations are presented. Because the tractor and trailer act as a system, with each part affecting the energy use of the other, options to reduce energy use of the tractor are also briefly discussed. While tractors are built for the weight Classes of 8, 7, and 6, the most populous, versatile and the default industry workhorses are Class 8 tractors. Reduced tare weight is noted as a contributor to reduced energy consumption (or, alternatively, to marginally increased payload) and is not discussed further. A fully loaded Class 8 tractor-trailer combination operating on the interstate at a constant 65 mph typically demands over 200 hp from the engine. This power demand is principally to drive the wheels at freeway speeds to overcome aerodynamic drag and tire rolling resistance. The remaining power demand, in the absence of grade or headwinds, is to overcome drivetrain friction and to power auxiliary devices. Table 6-1 details these demands. Class 8 tractor-trailers account for 60 percent of the fuel used by all on-road heavy-duty trucks (ICCT, 2013). The disproportionate fuel use notwithstanding, Class 8 tractor-trailers are relatively small in number because of the just-mentioned high power demands at freeway speeds (65 mph) and the high annual mileages accumulated by these vehicles (a median of about 100,000). By comparison, Class 3 to Class 6 fully loaded delivery trucks requires less than a third of the power to operate at a constant urban speed of 40 mph, and they each accumulate fewer miles per year (a median of about 40,000) (NRC, 2010, Tables 2-1 and 5-2). Therefore, straight trucks with these predominately urban duty cycles will not be further considered in this chapter. TABLE 6-1 Operational Power Demands from Class 8 Tractors with Sleeper Cab-Van Trailers at 65 mph on a Level Road and Having a Gross Vehicle Weight (GVW) of 80,000 lb Operating Load Power Consumed (hp) Power Consumed (%) Aerodynamic 114 53 Rolling resistance 68 32 Auxiliaries 20 9 Drivetrain 12 6 Total 214 100 SOURCE: NRC, 2010, Table 5-4. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-2 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS In addition to trailers towed by tractors, some trailers are also transported by rail. “Intermodal transport” refers the movement of goods by more than one mode on a single journey (Corbett and Winebrake, 2007; Winebrake et al., 2008). Commonly, intermodal transport combines a truck mode with either ship or rail to improve shipping efficiency, reduce costs, or achieve some other desirable performance attribute. Because rail and ship are significantly less energy-intensive than truck, incentivizing the movement of goods from truck to rail or ship is one way to improve the overall efficiency of the freight transportation system. (NRC, 2010, p. 175) Containers are transported at each end of their route by truck tractors. These final segments are typically much shorter than the total journey of the container. The container is on- and off-loaded to a chassis, which completes the trailer configuration (sometimes standard van trailers are also rail transported). When the notion of adding trailer aerodynamic devices is considered later in this chapter, the potential interference of those devices with container handling must be considered. BACKGROUND Current Tractor-Trailer Energy Balance Efficiency of Class 8 tractor-trailers can also be improved by reducing energy losses in the engine processes. As shown in Figure 6-1, half the fuel energy available to the engine is typically lost to heat. Another 8 percent of the fuel energy is lost to overcoming pressure differentials and friction and to power accessories. The remaining energy available, 42 percent, is the operational power demand from the engine and distributes, as summarized in Table 6-1. Note that not all Class 8 combination trucks operate primarily at high interstate speeds, nor do they all carry high gross weights. Indeed, many operate in shorter regional haul or mixed highway and suburban duties and often carry partial loads. Still others may operate substantially in suburban and urban areas, often with frequent stops. Often these shorter haul duties utilize day cab tractors, typically returning to central dispatch for overnight domicile. These descriptions serve to clarify that there is a continuum of duties in the tractor-trailer universe, and the benefit of technologies that reduce fuel use will vary widely depending on speed, the load being carried, and the mileage accumulated. Aerodynamics and Tire Rolling Resistance of the Tractor-Trailer The power required to propel a vehicle at any moment in time is customarily presented as a “road load equation.” This power equation has four terms to describe tire rolling resistance, aerodynamic drag, acceleration, and grade effects: P RL = mgC rr Vcos(θ) + 0.5C d Aρ a V3 + mV(dV/dt) + mgsin(θ)V where P RL is road load power, mg is vehicle weight, C rr is tire rolling resistance, C d is a drag coefficient based onthe entire vehicle, A is frontal the area, ρ a is the air density, V is the vehicle velocity, m is vehicle mass, t is time, and θ is the road gradient (uphill positive). Neither C d nor C rr need be constant with respect to speed and are not treated as constant in the better simulations. The term C d A should not be separated as it arguably represents a fundamental characteristic of the vehicle for which it has been determined. The power required to overcome aerodynamic drag is proportional to the cube of forward velocity. This illustrates the important influence of vehicle speed on horsepower demand and the fuel consumption needed to overcome aerodynamic drag. The power required to overcome tire rolling resistance is proportional to the forward velocity. These relationships are shown in Figure 6-2. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-3 FIGURE 6-1 Energy balance of a fully loaded Class 8 tractor-trailer on a level road at 65 MPH. SOURCE: NRC (2010), Figure 5-1. Tractor-Trailer Operating Consumptions 80,000 lbs GVW 120 100 Consumption (HP) 80 60 40 20 0 0 10 20 30 40 50 60 70 Speed (MPH) Aero-hp w/Cd=0.625 Tires-hp w/Crr=0.0068 FIGURE 6-2 Aerodynamics and tire power consumption for a late-model tractor-trailer combination with GVW of 80,000 lb. SOURCE: NRC, 2012, Figure 5-1. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-4 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS FIGURE 6-3 Tractor-trailer combination truck illustrating regions of potential fuel consumption reduction; combined C d base of 0.625. SOURCE: NRC, 2010, Figure 5-8. Notice that these two power demands are equal at about 50 mph, while rolling resistance power consumption at 36 mph is about twice that required to overcome aerodynamic drag. This comparison is for a fully loaded circa MY2007 tractor 1 and a trailer that does not incorporate aerodynamic devices. An empty or partially loaded trailer would have less rolling resistance because the rolling resistance force is also proportional to the weight on the tires. Aerodynamics of the Combined Tractor-Trailer There are four regions of the tractor-van trailer combination truck that are amenable to aerodynamic design improvements. These regions include the various tractor details, the tractor-trailer gap, the trailer underbody, and the trailer tail (NRC, 2010, p. 96). These are illustrated in Figure 6-3, along with the estimated fuel consumption reductions that might be realized for trailers with aerodynamic devices and present-generation sleeper tractors. Tractor Aerodynamics od and fender styling changes, plus aerodynamic bumpers and fuel tank fairings and by moving the externally mounted air cleaner canister under the hood. These changes were led by the introduction of 1 Model years vary significantly among medium- and heavy-duty vehicle (MHDV) manufacturers, so for the sake of simplicity and uniformity the calendar year is often used as the rough approximation for model year. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-5 Kenworth’s T600 tractor model in 1985. That game-changing introduction spurred the entire industry to accelerate aerodynamic tractor styling, as customers began to measure fuel consumption reduction effects. The current aerodynamic features for tractors are identified in Figure 6-4 and can be seen in the photos in Figure 6-5, which illustrates the most significant aerodynamic differences and similarities between aerodynamic and nonaerodynamic tractors. Panel (a) shows a MY2013 aerodynamic high-roof sleeper cab tractor, equipped with aerodynamic hood, fenders, bumper and mirrors, side fairings, and an integrated roof fairing with cab extenders that help reduce the turbulent area between the cab and the front of the trailer. Panel (b) depicts a day cab tractor equipped with only a simple roof air deflector and no side fairings, yet common cab, hood, fenders, bumper and mirrors. As the truck industry rarely reports C d values, such figures are not available for the tractors shown. Indeed, tractor-only C d values are of limited value, since the combined drag of the tractor and trailer is most significant to the truck’s fuel consumption. Tractor manufacturers introduce design modifications periodically, and their advertisements often claim aero-related performance improvements (including for engine performance). Indeed, these often are declared by the manufacturers to be major, competitive, purchase-worthy steps forward. It is anticipated that the Department of Energy (DOE) SuperTruck projects 2 will generate significant aerodynamic innovations when they conclude between 2014 and 2016. The Phase I Rule also provides a strong incentive to tractor manufacturers to continuously reduce fuel consumption. Aero Side Roof Cab Mirror Fairing Extender Aero Hood & Fender Aero Bumper Chassis Full Side Fairing Fairing FIGURE 6-4 Sleeper tractor with aerodynamic features identified. SOURCE: NRC, 2010, Figure 5-5. 2 SuperTruck is a major initiative of DOE’s 21st Century Truck Partnership and is supported by three other federal agencies in cooperation with fifteen industrial partners. The latter include all six U.S. heavy-duty truck manufacturers and many heavy duty engine and powertrain system manufacturers in order to accelerate technology development and provide focus for R&D efforts. The four industry-led projects, spanning 2010 through 2016, were established to fund R & D and demonstration of full vehicle systems integrating a number of technologies into Class 8 heavy-duty, long-haul trucks. There are three major goals: (1) Demonstrate a 50% increase in freight efficiency (measured in ton-miles per gallon) on a defined drive cycle with a 20% engine contribution; (2) Demonstrate engine 50% brake thermal efficiency (BTE) at a level road load of 65,000 lbs, 65 mph; and (3) Conduct technology development and scoping for a path to 55% BTE. Source: Ken Howden, DOE, “21st Century Truck Partnership and SuperTruck Initiative,” presentation to the committee, March 29, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-6 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS (b) (a) FIGURE 6-5 (a) Peterbilt aerodynamic high sleeper cab and (b) day cab model 579 tractors. SOURCE: Courtesy Peterbilt Motors Corp., 2013. Van Trailer Aerodynamics Improvements to the aerodynamics of van trailers are influenced by customer demand for reduced fuel consumption, the Environmental Protection Agency’s (EPA’s) SmartWay voluntary program, and GHG regulations of the California Air Resources Board (CARB) (discussed in a later section). The current federal Phase I Regulations on fuel economy and GHG apply only to engines and tractors and do not require trailer manufacturers to reduce the impact of their trailers on tractor fuel consumption. The most common improvement to trailers is the addition of side skirts to improve underbody aerodynamics (see discussion in the section “Current Use of Aerodynamic Devices and Low Rolling Resistance Tires”).These may be added to new trailers or retrofitted to existing trailers. The CARB regulation includes a GHG reduction requirement that is most easily met with skirt retrofits, and this has created a burgeoning aftermarket for them. Other types of devices such as nose cones and rear fairings are used on a small fraction of trailers. EPA testing shows that most side skirts provide a 5 percent fuel saving at 65 mph (3 percent at 55 mph), as do most rear tail fairings (see Table 6-2). Other devices such as trailer front gap devices (see Figure 6-6), wheel covers and fairings, and vortex generators and flow tabs have been developed. Overall, the use of trailer aerodynamic devices has grown significantly in the past few years. See the SmartWay discussion below that references devices verified or qualified in that program. TABLE 6-2 SmartWay-Verified Devices for Heavy-Duty Tractor/Trailers Device Fuel Economy (mpg) Improvement (%) Number Verified Advanced trailer side skirts ≥5 37 Trailer side skirts ≥4 16 Advanced trailer end fairings ≥5 9 Trailer boat tails ≥1 9 Trailer gap reducers ≥1 4 LRR tires (new) ≥3 41 brands LRR retreads ≥3 7 brands Certified tractors Specifies design elements 19 models Certified 53+ ft trailers (new) Specifies aerodynamic configurations 8 manufacturers NOTE: mpg, miles per gallon. SOURCE: www.epa.gov/smartway/forpartners/technology.htm. Accessed August 29, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-7 Tractor-Trailer Gap The airstream leaving the tractor cab encounters the gap between tractor and trailer. 3 The gap is highly turbulent with air motion out of control and pressure further reduced. Yet behind an aerodynamic tractor, many measurements have identified this region as providing only a 0.5 to 3.5 percent opportunity for drag reduction (TIAX, 2009). An average performance of 1.3 percent was achieved with partial gap closures and 2.2 percent with full gap closures. Because the CARB regulation requires any trailer aero- performance improvement to reduce fuel consumption by at least 5 percent, which can be achieved by using skirts under the van trailer body, the typical partial gap closure devices on offer are utilized only infrequently. 4 FIGURE 6-6 Trailer front gap fairing. SOURCE: Courtesy of Freight Wing, Inc. Available at http://www.freightwing.com/gap_fairing.php. Accessed November 14, 2013. Tire Rolling Resistance Nearly all heavy-truck tire manufacturers produce low rolling resistance (LRR) tires for all wheel positions on tractor trailers, and many of these have been performance verified by SmartWay. SmartWay requires meeting specific rolling resistance targets based on test data in order to be verified. Achieving the target values results in a 15 percent reduction in rolling resistance, measured against a 2010 baseline tire. Best-in-class tires provide a 30 percent reduction in rolling resistance, indicating that still greater reductions in rolling resistance beyond the SmartWay targets are possible (76 Fed. Reg. 57207). Improvements in rolling resistance have been achieved with new tread compounds, stabilization of the tread block, and stiffer shoulders to reduce tread deformation. (Note that a 15 percent reduction in C rr for the entire truck translates into a reduction of about 3 percent in fuel consumption.) Manufacturers have also introduced wide base single tires (a), many of which feature lower rolling resistance than most dual tire sets and most often produce best in class Crr. The WBST must be mounted on a special wheel and axle end, which increases cost, but has the additional benefit of reducing wheel weight and thus increasing payload capacity. Tread life and retreadability also play into a carrier’s analysis of how to achieve the lowest costs over a tire’s life cycle. Following is a treatise on the factors influencing successful WBST use, offered by an experienced truck industry executive (though not a tire manufacturer): 3 Freight Wing, Inc. “On Aerodynamics: The Effect of Aerodynamics on Tractor Trailers.” Available at http://www.freightwing.com/on-aerodynamics.php. Accessed December 18, 2013. 4 Sean Graham, Freight Wing Incorporated, personal communication with Chuck Salter, committee member, August 26, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-8 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS These experiences are primarily those for over the road, tractor-trailer fleets. Wide Base Single Tires (WBST) make up less than 5% of the commercial truck tire market, but their use is increasing due to fleets’ desires to reduce fuel consumption and greenhouse gas emissions. Since 2000 when first introduced by Michelin, many fleets have tried and adopted them while others have tried and abandoned them for several reasons. Satisfied fleets feel the savings in fuel (between 2 and 5%) greatly offsets any disadvantage in tread wear and tire life. These fleets often utilize automatic tire inflation systems to keep the tires running when trailers encounter road hazards that puncture the casing so that they can get home for repairs. Fleets that abandoned them usually did so because they did not provide necessary maintenance and experienced high numbers of emergency breakdowns. Some fleets experienced extremely long breakdown periods (e.g., double the 2 hours for standard tires), often due to unavailability of wide base spare tires especially in certain areas of the country. WBSTs are very sensitive to both under and over inflation. The Tire & Wheel (S.2) Study Group of the Technology & Maintenance Council found fleets experiencing both shoulders wearing away usually were over-inflating these tires. Accordingly several tire manufacturers now recommend 100 psi as the optimal pressure to avoid this condition. Tire Pressure Systems (TPS) are clearly a robust solution to maintaining proper tire pressure for WBSTs, as well as steer and dual tires. See Subsection 6.4.1 below for an extended discussion on the value of TPS. WBSTs are also more sensitive to free rolling wear which is aggravated by lightly loaded trailers. Negative camber in the axle can cause the shoulder to wear prematurely which can be a big issue for fleets hauling heavier loads. Irregular wear negatively impacts tread mileage. In addition WBSTs usually come with slightly less tread depth than standard dual tires. Some fleets report getting 50-60% of the tread mileage they experience with duals. Yet other fleets achieve e tread mileage nearly equal to dual tires, through inflation maintenance and proper alignment. Improvements in compounding and tread design find WBST tread life now approaching the same rate as dual tires. Early retreadability of WBSTs was unsuccessful due to their higher unit loads causing faster casing fatigue. Now, most fleets usually get 1 retread from a wide base casing. This is certainly a short fall for fleets that routinely get 2 retreads on standard dual tires. But again, the savings in fuel economy can make up for this short fall. Some of the problems attributed to the reduction in retreads fall on retreaders, some of which are still climbing their learning curve. 5 Tire manufacturers have variously reported the following for WBST tread life: • With wide-base C rr 15 percent below duals (the most popular wide base), it is 67 percent or more of tread life of dual tires. • WBST tread life is nearly equal to the tread life of duals manufactured to the same Crr. It is noted from the foregoing that while the use of WBST LRR tires results in better fuel economy, the shorter tread life of these tires may lead to an increase in the number of newly manufactured tires and retreads, thereby generating additional life-cycle GHG emissions. The balance between these contrary effects is not known. 5 Peggy J. Fisher, President, TireStamp, Inc., “Low Profile Metric Wide Base Radial Tire Issues,” personal communication to Chuck Salter, committee member, November 7, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-9 GOVERNMENT PROGRAMS THAT INFLUENCE TRACTOR-TRAILER FUEL CONSUMPTION SmartWay SmartWay was formed in 2004 as a collaboration of the EPA and the goods movement industry. The objective of SmartWay is improving efficiency and reducing fuel consumption and pollution from the movement of freight across the supply chain. Currently its focus is on-road trucking, which carries the majority of the nation’s freight. The completely voluntary SmartWay Partnership grew more than 10-fold between 2006 and 2012 to 3,000 partners. 6 Partners agree to provide data on their operations, which are input into standardized tools to produce a measurement of environmental efficiency, such as grams pollutant per ton-mile. These benchmark results are compared to similar categories of freight movement—for example, dry vans—and ranked in quintiles. Fleet operators and shippers use the results to improve their efficiency, identify green options, and achieve recognition. SmartWay also includes a Technology Program that certifies the performance of technologies, equipment, and strategies that save fuel and reduce emissions. This process increases the certainty for potential users of equipment and strategies that fuel savings will occur and a reasonable return on investment can be achieved. The technology program verifies the fuel savings of new tractors, new trailers, aerodynamic devices retrofitted to trailers, and LRR tires. New tractors are verified by design category based on their use of an integrated high roof sleeper cab fairing, cab side extenders, fuel tank fairings, aerodynamic bumpers and mirrors, LRR tires, or a device that provides 8 hr of idle-free power and cabin conditioning. No testing is required. New dry van (nonrefrigerated) trailers 53 feet or longer (“53+ ft”) may also be verified. Verification is based on use of a combination of SmartWay-certified devices and tires that reduce trailer drag and rolling resistance and provide at least a 6.5 percent reduction in fuel use relative to a baseline trailer. Typically this includes use of an advanced trailer skirt or, less frequently, an advanced trailer end fairing (“advanced” refers to a device verified to provide at least a 5 percent reduction in fuel use). Other combinations of verified devices are possible. Trailers must also use verified LRR tires. Aerodynamic devices designed to be retrofitted onto trailers must be tested to demonstrate their fuel reduction efficacy. The test involves comparing the fuel use of two identical trucks, one equipped with the drag reducing device(s) and driven on a dry, closed-loop test track in low wind conditions at no more than 65 miles per hour and the other not so equipped . The procedure is specified as modified Society of Automotive Engineers (SAE) standard J1321. The results place the device into one of five verification categories: gap reducers, end fairings (1 percent or greater reduction in fuel use, each), side skirts (4 percent or greater), advanced skirts or rear fairings (5 percent or greater, each). This test may also be used for other types of aerodynamic devices provided EPA establishes a new SmartWay verification category for the technology. 7 To add some perspective to this test procedure’s maximum speed, it is instructive to review the Freight Performance Measure study by the Federal Highway Administration of the five busiest interstate highways, which together account for nearly 25 percent of interstate freight vehicle miles traveled. Average truck speed deficits from posted limits are attributable to numerous causes, infrastructure design and capacity being the most common cause, plus terrain, weather, accidents, work zones, and time of travel (including operational strategy). That analysis showed an annual average for the four highest speed highways (of the five) in the range of 54 to 58 mph, road by road. The worst interstate was I5 at 50 mph, 6 Sam Walzer and Cheryl Bynum, EPA, “US National Approach to Reducing Freight Emissions,” personal communication to Tom Cackette and Chuck Salter, committee members, July 24, 2013. 7 Detailed requirements for obtaining SmartWay verification for tractors and trailers may be found at http://epa.gov/smartway/technology/designated-tractors-trailers.htm. Accessed August 29, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-10 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS surprising few. Implied, is that certain of the remaining interstates may embody somewhat higher averages, to be determined by a second study. This suggests that test procedures evaluating the fuel savings of aerodynamic devices should include the variety of speeds experienced on real roads (FHWA, 2006). LRR tires may be verified using the SAE J1269 or ISO 28580 test procedures, which involve measuring the steady-state rotational force required to turn the tire against a drum under specified conditions. To be SmartWay verified, the tire’s rolling resistance coefficient must be less than EPA’s target values, which vary depending on where the tire is positioned on the tractor/trailer. In general, LRR tires reduce fuel use by about 3 percent, with roughly half the reduction coming from the trailer. In June 2012, EPA also issued an interim protocol and procedures for measuring rolling resistance of retread truck tires. 8 SmartWay Verified Technologies Only three of the eight trailer manufacturers with SmartWay-verified 53+ ft trailers highlight the use of side skirts or the SmartWay program through use of pictures and/or discussion on their websites. Two make no mention at all, and the rest offer skirts through an option list. Only one mentions the regulatory requirements of California. Most major commercial truck tire manufacturers discuss on their websites tire models that reduce fuel use and mention SmartWay-verified models in their tire selector or in brochures. Classes 7 and 8 tractor manufacturers all highlight aerodynamics and fuel efficiency of their trucks, but they continue to produce some Class 8 models that offer the “classic look,” which does not utilize hood shapes and fuel tank covers that reduce aerodynamic drag. These are typically designed to haul flatbed trailers and tankers; one manufacturer reports that the classic design accounts for less than 5 percent of new tractor sales. SmartWay also verifies idling reduction devices (which may be exempt from federal excise tax) and retrofit devices aimed at reducing smog-forming criteria emissions. Improvements to SmartWay EPA is undertaking studies to correlate the on-road performance of devices with the results of manufacturer verification testing. For example, an EPA contractor is conducting on-road fuel consumption testing pursuant to SAE J1321 of verified tires and aerodynamic devices to establish correlations with laboratory and track verification test results. One objective is refining current procedures used for verification. Such attention to test procedure improvement is necessary and timely. During the committee discussions and data collection with tractor, trailer, and aerodynamic device manufacturing personnel, inadequacy of the required J1321 procedure was frequently cited. 9, 10 Significant issues include the following: • Regulation demands more precision than a voluntary SmartWay program. Fuel consumption reduction verification in the range 1 to 7 percent requires better than the current plus or minus (±) 1 percent reported in J1321. 8 Further information available at http: http://www.epa.gov/smartway/forpartners/technology.htm. Accessed February 13, 2014. 9 Jeff Bennett, Utility Trailer Manufacturing Company, personal communication to Chuck Salter, committee member, August 29, 2013. 10 Sean Graham, Freight Wing, Inc, personal communication to Chuck Salter, committee member, August 26, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-11 • Supposedly identical tests run several months apart showed a 2 percentage point variation in fuel consumption reduction (first 4 percent then 6 percent). • Results from an aero-device manufacturer’s test could not be replicated within 2 percentage points by a trailer manufacturer. • Results between test facilities were sometimes not precise within 2 to 3 percent percentage points. • A single trailer sometimes performed very differently when towed with different SmartWay- verified sleeper tractors. Improvement of the precision of SAE J1321 aerodynamics test procedure appears particularly important. Dissemination of these results to fleets and operators will increase confidence in the efficacy of fuel-saving devices. Scale-model wind tunnel testing for trailers is also being conducted to establish correlation to on- road performance. Scale-model wind tunnel testing could reduce the cost of verification for trailer aerodynamic devices. SAE has developed recommended practice SAE J1252 for this testing. A wind tunnel procedure is the only accurate method of determining wind-average drag, by accounting for the effects of side winds. A test procedure that has no systematic process to account for yaw calls into question the value of devices that perform at a higher level in the presence of yawing wind. It will be key for EPA to establish a good correlation between wind tunnel tests and its modified J1321 on-road tests to help reduce the costs of development and verification for aero devices. It is significant to note that at least three of DOE’s four SuperTruck project teams are utilizing either scale-model or full-size wind tunnels to provide quality analysis for the aero component of those projects.11 The EPA is also exploring the possibility of using computational fluid dynamics (CFD) to determine trailer aerodynamic drag for use in verification. CFD continues to be applied to full truck aero developments. Here again, three of four SuperTruck project teams report using these flow visualizing and quantifying tools to reduce analysis time and avoid prototype builds. EPA should consider processes to permit the results of these time- and cost-saving tools to satisfy performance verification requirements. Lab testing of new and retread tires is being conducted to establish correlation to road testing and to potentially improve the current lab procedures. This may lead to improvements to the test procedures for verifying the efficacy of SmartWay-verified devices, trailers, and tires. Finally, EPA is testing SmartWay idle reduction systems in a full-scale environmental chamber to better understand the energy load demand on the truck cab and explore a performance-based protocol for aero devices. 12 EPA is considering inclusion of refrigerated 53+ ft van trailers and twin trailers (twin 28 ft pups) in SmartWay. It is also evaluating adding an “Elite” category for SmartWay trailers that has a higher fuel savings target, such as 10 percent. This could be met by use of multiple aerodynamic devices such as advanced side skirts and an advanced rear fairing (each providing a 5 percent reduction).4 11 U.S. Department of Energy Vehicle Technologies Office, Annual Merit Review and Peer Evaluation Meeting. May 13-17, 2013. Available at Accessed November 5, 2013. 12 Sam Walzer and Cheryl Bynum, U.S. Environmental Protection Agency, “SmartWay Technology Program: Influencing Efficient Freight Movement into the Future,” personal communication to Tom Cackette and Chuck Salter, NRC Committee on Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles, Phase Two, July 24, 2013. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-23 • Although the ISO28580 rolling resistance test procedure calls for the correlation of measurement results, the industry lacks a master equipment correlation lab that would help assure consistent C rr values are achieved across the industry. • WBSTs are designated in the United States by the metric sizes 445/50R22.5 and 455/55R22.5. These sizes need to be specified so as to differentiate them from early “super singles,” which performed poorly. Super single issues are discussed in NRC (2010, p. 113). • At least 50 percent of long-haul tires are retreads. SmartWay retread performance levels were specified by EPA in June 2012. Yet retread C rr performance hurdles (i.e., the maximum value allowed by EPA SmartWay specifications) are higher by 9 to 17 percent than new tire hurdles. And manufacturing and audit controls are believed more lax than for original equipment tires. This represents another opportunity for reducing fuel consumption. Some barriers to WBST adoption were also identified. Those believed most significant are the following: • Inability to run flat. Automatic tire inflation systems can significantly reduce in this potential hazard. See the next section, “Tire Pressure Systems.” (Note that operating on a flat tire is not allowed by FMCSR 393.75.) • Life-cycle cost remains unsure if the various components such as tread life or downtime due to flats, as well as the comparability of the C rr s themselves, are not correctly estimated. • Tread life, which—as noted elsewhere—may be as much as a third shorter than that of dual tires, • The number of allowable retreads is usually one, compared to two and sometimes three for duals. Overall, about half of SmartWay-verified LRR tire usage is for new equipment and 42 percent for replacement tires. Greater use of LRR tires on new tractors could occur as a result of the Phase I Rule. It is uncertain if greater use of LRR tires on new trailers and for replacement tires will occur in the absence of requirements or incentives. Tire Pressure Systems There are two primary types of tire pressure systems: tire pressure monitoring systems (TPMS), which use sensors in various configurations and locations to sense and communicate tire pressure, and automatic tire inflation systems (ATIS), which inflate tires when pressure is low and, in and some cases, can deflate tires to correct for pressure rises when the temperature increases. One tire manufacturer remarked that tire pressure systems may be nearly as significant for GHG reduction as lower C rr . One trailer manufacturer reported that 60 percent of its van trailers had been equipped with these systems over the most recent 12 months of production. Likewise, one tire manufacturer reported 40 percent of its trailer tires were equipped with TPS sensors. These industry reports are corroborated by a U.S. Department Transportation (DOT) study (2008) on the effectiveness of TPMS. These are some of its findings: • Improper tire inflation leads to accelerated tire wear (which subsequently leads to compromised braking, poor handling, and reduced stability); increased fuel consumption; greater propensity for catastrophic tire failures (blowouts); more dangerous roadside debris; and an increased number of road calls to repair deflated tires. • Approximately 7 percent of all tires are underinflated by 20 psi or more. Only 44 percent of all tires are within 5 psi of their target pressure. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-24 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS  Tire-related costs are the single largest maintenance cost item for commercial vehicle fleet operators.  Improper tire inflation reduces fuel economy by about 0.6 percent. Another DOT study (2007) included these important observations:  Tire pressure monitoring and inflation systems greatly simplify the task of checking and maintaining tire pressure.  There is significant diversity in the design and technological approach of the marketplace’s offering of tire inflation and monitoring systems.  Commercial vehicle tire inflation and condition directly link to stopping distance and handling and thus to overall safety. Properly maintained and performing tires aid drivers in preventing and mitigating crash situations. There are 18 or more manufacturers of various types of commercial vehicle tire pressure monitors in North America. Monitor systems are generally characterized by the location of their sensor mounting: on the valve stem (currently the most prevalent in company offerings), on the wheel, or in the tire. Inflation systems are characterized by the nature of the air supply and variable or constant inflation, with the latter the most prevalent in company offerings. Variable inflation pressure is typically utilized to facilitate increased traction, particularly in off-road situations or certain reduced-speed applications. At least a dozen companies offer these products. Both handheld and in-cab readouts are offered. The North American Council for Freight Efficiency (NACFE) published a report on these systems in August 2013, in which it concluded there are three benefits to carriers for the introduction of such systems, including the decrease in roadside breakdowns due to blowouts caused by underinflation, longer life for the tires, and improved fuel efficiency. These benefits depend on the effectiveness of a fleet’s manual tire pressure maintenance system before a device is installed, but the investment in such systems for trailers was recouped in about 8 months. Finally, NACFE estimates that 40 percent of new trailers are being manufactured with TPS, with ATIS outnumbering TPMS by about 3 to 1. There is a huge body of experience with TPMS in the U.S. light-duty vehicle category. Beginning on October 5, 2005 (and phased in through September 1, 2007), such systems (TPMS) have been required on all four-wheel vehicles up to 10,000 lb GVWR (DOT, 2007). Following a meeting in the spring of 2011 of ATA’s Technology and Maintenance Council, an article appeared in TireBusiness.com entitled “Time for feds to act on truck TPMS.”23 It noted that fleets were continuing to adopt TPMS and ATIS on both tractors and trailers, in acknowledgement that they increase the life of tires and improve fuel economy (test fleets reported a 1.4 percent increase). These improvements came in addition to the safety enhancements reported by the aforementioned DOT study (2007). The industry article encouraged the FMCSA to soon issue a recommendation for the use of TPMS on commercial vehicles. That would give fleets direction as to which type of products they should or must use to better monitor and maintain their tires. The author concluded that by integrating tire monitoring and inflation systems with telematics24 communication systems, fleets will greatly improve their tire maintenance, fuel economy and safety and will reduce their tire costs-per-mile and in-route breakdowns. 23 TireBusiness.com, Crain Communication, Inc., “Time for feds to act on truck TPMS, Detroit, Mich., March 28, 2011 24 Denotes the use of devices that incorporate both telecommunications and informatics. See, for example, www.telematics.com. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-25 A recent response from NHTSA is its solicitation of input on truck tire maintenance practices to help determine the impact of TPS on commercial vehicle fuel economy. This information solicitation is to support its study on feasible fuel-economy standards for medium and heavy-duty trucks for MY2019 and beyond. 25 FINDINGS AND RECOMMENDATIONS Trailers Finding: When a trailer is not owned by the tractor owner/operator (who pays for fuel), there is no incentive for the trailer owner to purchase fuel-saving devices. Finding: In a survey of trailer manufacturers responsible for two-thirds of industry sales, it was found that only 40 percent of new van trailers come equipped with fuel saving aerodynamic devices such as side skirts, which suggests that fuel saving is not a dominant consideration in purchasing a new van trailer. Finding: Only a few van trailer manufacturers promote use of aerodynamic device-equipped trailers on their websites; others will install devices if requested by the customer, which chooses from an option list. Finding: The benefits and favorable return on investment that result from more efficient van trailers have been demonstrated by testing and fleet feedback. Use of trailer aerodynamic devices on van trailers, in particular side skirts, provides a full return on investment through fuel savings in about 1 year, on average. Yet the majority of both new and in-use van trailers currently do not use these fuel saving devices. Finding: A California regulation requires operators of van trailers to use aerodynamic devices to reduce the energy required to pull them. Observations made in California and Arizona showed a greater proportion of trailers with aerodynamic devices than did those observations made in Oregon, Texas, Michigan, Pennsylvania and Maryland. Side skirts were overwhelmingly the predominant aerodynamic devices strategy. Other strategies (underbody fairings and rear fairings) were observed in relatively few instances. Finding: Trailer manufacturers report that compliance with California’s regulation is of greater interest than fuel savings when decisions are made on new van trailer purchases. This suggests it is doubtful that the U.S. fleet’s use of fuel efficient trailers will become universal in the absence of a regulation or other strong incentive. Recommendation 6.1: NHTSA, in coordination with EPA, should adopt a regulation requiring that all new, 53 ft and longer dry van and refrigerated van trailers meet performance standards that will reduce their fuel consumption and CO 2 emissions. The lead time to implement this regulation should be evaluated independently from lead time requirements applicable to the next set of standards for new engines and tractors, because less time is needed to perform compliance testing and install aerodynamic devices on new trailers. The agencies should also collect real world data on fleet use of aerodynamic trailers to help inform the regulation. Finding: The current SmartWay program and CARB regulation address only the most commonly used trailer, the 53 ft or longer van trailer, which, among those manufacturers surveyed by the committee, 25 TireBusiness.com. “NHTSA To Study Mileage Impact of Truck TPMS” December 14, 2012. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-26 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS accounts for about 60 percent of the trailers that could benefit from the use of aerodynamic devices. Use of aerodynamic devices on other types of trailers, such as container/chassis and shorter vans including dual trailers (“pups”) could provide additional fuel savings of 4 to 9 percent per tractor-trailer, according to industry estimates. Fuel savings from the use of side skirts have also been demonstrated on flatbed trailers. The cost effectiveness of using aerodynamic devices on these additional categories of trailers depends on their annual mileage and average speed, among other considerations such as access to the trailer underbody, and needs further assessment and quantification. Recommendation 6.2: NHTSA, in coordination with EPA, should determine whether it would be practical and cost effective to include with the regulation of van trailers the regulation of other types of trailers such as pups, flatbeds and container carriers, as doing so could substantially increase overall fuel savings. Finding: Both trailer and aero-device manufacturers report that based on replicate tests and testing across different facilities, fuel consumption results determined by the SAE J1321 test procedure lack the necessary precision for accurately assessing the small incremental improvements provided by aerodynamic devices. Depending on the device evaluated, the procedure-specified precision range can be as much as 100 percent of the result. Finding: The relative fidelity of test results from the coastdown procedure as opposed to results from a powered on-track test is not known. Fidelity is believed the critical parameter in test procedure selection for trailer regulation. Finding: Aerodynamic practitioners recognize that both wind tunnel testing and computational fluid dynamics (CFD) simulation can provide a good basis for development of aerodynamic surfaces and devices. Both wind tunnel and CFD methods can reduce the cost of development, may avoid the building of multiple full-size prototypes, and can shorten development time for the final product. Finding: The committee’s discussions with trailer manufacturers indicate that not all end-users are confident of the fuel savings that will be realized from using aerodynamic devices on trailers. Improvement of test precision and repeatability may help address this concern. Recommendation 6.3: NHTSA should evaluate the relative fidelities of the coastdown procedure and candidate powered procedures to define an optimum prescribed full-vehicle test procedure and process; and should validate the improved procedure against real world vehicle testing. Further, the Agencies should assess if adding yaw loads to the validation process provides significantly increased value to the Cd result. In addition, the Agencies should disseminate to end users updated test data and fuel savings of efficient trailers, aerodynamic devices, and tires, especially to those not participating in the SmartWay program. This should increase end-user confidence in fuel savings and device reliability. Tractors Finding: Among those manufacturers surveyed by the committee, nearly 60 percent of tractors sold are fully equipped sleepers whose fuel consumption already benefits from SmartWay specification. Because federal regulations that mandate improvements in tractor efficiency begin in 2014, the fraction of efficient tractors sold will likely quickly increase. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-27 Tractors and Trailers Finding: Tire Pressure Monitoring Systems (TPMS) and Automatic Tire Inflation Systems (ATIS) (collectively Tire Pressure Systems) are being increasingly accepted by fleets for their operational benefits (fewer flats, reduced fuel consumption and longer tire life) and considerable safety benefits (uncompromised vehicle stability and short stopping distances). Finding: The commercial vehicle industry has no standards for any of the following: TPS designation, minimum performance for various system types, driver displays, and testing procedures for system validations. Recommendation 6.4: The lack of standardization on TPS for commercial vehicles might be appropriately remedied by professional or industry organizations such as the Society of Automotive Engineers, or the Technology and Maintenance Council or by the collaboration of such organizations. In support of that activity, it would be beneficial for NHTSA to prepare a white paper to clarify the minimum TPS performance needed from a safety perspective. Tires Finding: Many new tractors and most new trailers are equipped with low rolling resistance tires that meet the SmartWay performance standard, and the share of vehicles so equipped is likely to increase owing to regulatory requirements. However, 70 percent of new tires sold in 2012 for use on tractors and trailers were for replacement of existing tires, and only 42 percent of these were SmartWay verified. There is no assurance that replacement tires will one day be as energy efficient as the original equipment tires they replace. Recommendation 6.5: NHTSA, in coordination with EPA, should further evaluate and quantify the rolling resistance of new tires, especially those sold as replacements. If additional, cost effective fuel savings can be achieved, NHTSA should adopt a regulation establishing a low rolling resistance performance standard for all new tires designed for tractor and trailer use. Finding: C rr measurement in tires is will have to be precise given the relatively modest fuel savings achievable with low rolling resistance tires. Further, while the ISO28580 test procedure is given good grades by most in the industry, there does not exist a robust machine cross-correlation for commercial vehicle tires in the United States. Carriers cannot depend on the comparability of C rr measurements from the approximately 60 tire suppliers verified by SmartWay. Recommendation 6.6: NHTSA, supported by EPA, should expeditiously establish and validate the equipment and process of a tire industry machine alignment laboratory and mandate the use of that laboratory by each tire manufacturer seeking C rr validation for any tires being offered as candidates in the GEM computation process, just as the C rr s of light-duty vehicle tires were validated. REFERENCES Argonne National Laboratory, Center for Transportation Research. 1999. Effects of Fuel Ethanol Use on Fuel-cycle Energy and GHG Emissions. January. Bachman, L., A. Erb, and C. Bynum. 2005. Effect of single wide tires and trailer aerodynamics on fuel consumption and NO x emissions of Class 8 line-haul tractor-trailers. SAE Paper 2005-01-3551. Warrendale, Pa.: SAE International. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-28 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS Berman, D.K. 2013. Daddy, what was a truck driver? Wall Street Journal, July 23. Button, K. 2010. Transport Economics, 3rd ed., Cheltenham, U.K.: Elgar. Clancy, H. 2013. How sensors promise to reinvent truck driving, Greenbiz.com, August 23. Conway, Peter. 2013. The next autonomous car is a truck. Strategy & Business 71. May 28. Corbett, J.J., and J.J. Winebrake. 2007. Sustainable movement of goods: Energy and environmental implications of trucks, trains, ships, and planes, Environmental Management (November): 8-12. Cummins, Inc. 2009. Framework for the Regulation of GHGs from Commercial Vehicles. Department of Transportation (DOT). 2007. Tire Pressure Monitoring and Maintenance Systems Performance Report, FMCSA-PSV-07-001. U.S. Department of Transportation: Washington, D.C. January. Department of Transportation (DOT). 2008. Commercial Vehicle Safety Technologies: Applications For Tire Pressure Monitoring and Management. Paper Number 09-0134,. U.S. Department of Transportation: Washington, D.C. Energy Information Administration (EIA). 2013. Annual Energy Outlook 2013: with Projections to 2030. Washington, D.C.: Energy Information Administration. EIA. 2012. Biofuels Issues and Trends. October Environmental Protection Agency EPA (EPA). 2010. Memorandum from Amy Kopin to the Docket titled “Truck and Trailer Roof Height Match Analysis.” August 9. EPA. 2011. GHG Emissions Model (GEM) User Guide. EPA-420-B-11-019. Washington, D.C.: U.S. Environmental Protection Agency. EPA and NHTSA. 2011a. Federal Register, Vol. 76, No.179, pp. 57106 to 57513. Sept. 15. EPA and NHTSA. 2011b. Final Rulemaking to Establish GHG Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles: Regulatory Impact Analysis. EPA-420-R-11-901. U.S. Environmental Protection Agency: Washington, D.C. August. Federal Highway Administration (FHWA). 2006. Freight Performance Measure: Travel Time in Freight Significant Corridors. Washington, D.C.: U.S. Department of Transportation. Federal Transit Authority. 2012. FTA fuel cell bus program: Research accomplishments through 2011. Available at http://www.fta.dot.gov/documents/FTA_Report_No._0014.pdf. March Gaines, L. 2006 Estimation of fuel use by idling commercial trucks, Paper 06-2567. Transportation Research Record: Journal of the Transportation Research Board Washington, D.C.: NRC. Hyard, A. 2013. Non-technological innovations for sustainable transport, Technical Forecasting & Social Change 80: 1375-1386. International Council on Clean Transportation 2013. Trailer technologies for increased heavy-duty vehicle efficiency—Technical, market, and policy considerations, White Paper, June. International Organization for Standardization (ISO). 2009. Passenger car, truck and bus tyres -- Methods of measuring rolling resistance -- Single point test and correlation of measurement results. ISO 28580:2009. Geneva: International Organization for Standardization. Merton, R.K. 1936. The unanticipated consequences of purposive social action. American Sociological Review 1:894-904. National Highway Traffic Safety Administration (NHTSA). 2010. Factors and considerations for establishing a fuel efficiency regulatory program for commercial medium- and heavy-duty vehicles. DOT HS 811 XXX, http://www.nhtsa.gov/staticfiles/rulemaking/pdf/cafe/NHTSA_Study_Trucks.pdf. NHTSA. 2012. Federal Register, Vol. 77, No. 244, p. 75257 to 75258. December 19. National Renewable Energy Laboratory. 2011. Celluosic ethanol technology on track to being competitive with other transportation fuels. NREL Highlights. February. National Research Council (NRC). 2001. Effectiveness and Impact of Corporate Average Fuel consumption (CAFE) Standards. Washington, D.C.: National Academy Press. NRC. 2009. Liquid Transportation Fuels from Coal and Biomass: Technological Status, Costs, and Environmental Impacts. Washington, D.C.: The National Academies Press. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-29 NRC. 2010. Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy- Duty Vehicles. Washington, D.C.: The National Academies Press. NRC. 2012. Review of the 21st Century Truck Partnership, Second Report. Washington, D.C.: The National Academies Press. North American Council for Freight Efficiency (NACFE) and Cascade Sierra Solutions. 2013. Barriers to the Increased Adoption of Fuel Efficiency Technologies in the North American On-Road Freight Sector. Fort Wayne, Ind.: NACFE. July. NACFE. 2013. Tire Pressure Systems— Confidence Report. Fort Wayne, Indi.: NACFE. August. New York Times. 2012. A big, and risky, energy bet. December 17. Oak Ridge National Laboratory (ORNL). 2009. Effect of Wide-Based Single Tires on Class-8 Combination Fuel Efficiency. Oscar Franzese, Helmut Knee, and Lee Slezak, October 28. Rubber Manufacturers Association (RMA). 2013. 2012 Tire shipments unchanged. Dan Zielinski, Washington, D.C., April 3. Society of Automotive Engineers. Undated. “Fuel Consumption In-Service Test Procedure Type III.” SAE International: Warrendale, PA. TIAX. 2009. Assessment of Fuel Consumption Technologies for Medium- and Heavy-Duty Vehicles. Report prepared for the National Academy of Sciences by TIAX LLC, Cupertino, Calif., July 31. White House. 2010. Presidential Memorandum Regarding Fuel Efficiency Standards. Washington, D.C.: Executive Office of the President. May 21. White House. 2013. The President’s Climate Action Plan. Washington, D.C.: Executive Office of the President. June. Winebrake, J.J., J.J. Corbett, A. Falzarano, J.S. Hawker, K. Korfmacher, S. Ketha, and S. Zilora. 2008. Assessing energy, environmental, and economic tradeoffs in intermodal freight transportation. Journal of the Air and Waste Management Association 58(8): 1004-1013. Yun, John M. 1997. Measuring the Unintended Effects and Costs of Fuel Consumption Regulation. Emory University. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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6-30 REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS ANNEX 6A QUESTIONS GIVEN TO VAN TRAILER MANUFACTURERS IN TABLE 6-5 Briefly describe your product type(s), sales volumes and typical selling price (OE and retrofit) for each (Perhaps you want to report the highest 1 or 2 performing devices, in each SmartWay category in which you produce): Identify sales volumes driven by 1. Customers’ Expected ROI, 2. Compliance to California Regulation, 3. Unknown: For described products, report SmartWay aerodynamic performance (and test procedure used for each: J1321 track, wind tunnel, coast down, other): Customer Acceptance: Please comment on what you believe are the biggest barriers to acceptance of each product type. E.g. customers lacking credible performance information; installed cost (customer uncertainty of information for ROI calculation; poor ROI), cost of performance certification; interference with normal driver functions; existing government regulations; other (specify) (list in approximate descending order). Include customer feedback. Describe any customer feedback you have received on maintenance or reliability issues. Are they resolved? What safety concerns or experiences have been reported by customers? Do you anticipate further performance improvements for any of the described product types in the next 5 + years? (Please be as specific as you can.) Are you collaborating with Tractor OEMs in product development? Which corporate entity do you think should be responsible for trailer performance certification, in the event of a greenhouse gas regulation which includes trailers? Tractor, Trailer, or Device manufacturer. Please explain your thinking. Are your products applicable to trailer types other than 53’ vans? What marketing incentives are absent that currently restrict those developments? Will you share aerodynamic performance results with your products on trailer types other than 53’ vans? PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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REVIEW OF OPTIONS TO REDUCE ENERGY USE OF TRAILERS 6-31 ANNEX 6B This annex reports the raw data from the observations of van trailers observed by 12 experts during August 2013 (Annex Table 6B-1). The contributors made these observations working at 10 locations, individually or in teams. The day and time of the observations was at the discretion of these individuals and did not follow a pre-set sampling plan so the results of this informal survey cannot be generalized. The accuracy of these observations was not verified. The locations were chosen to include, five locations in or near California—the major cross-country routes into California (e.g., I-80, I-15) and another route leading into California from Arizona (I-10)—and, five locations in disparate parts of the continental United States. The purpose was to explore the hypothesis that van trailers operating in, or destined for, California, which is the only state currently requiring the use of aerodynamic devices, would have a higher observed incidence of aerodynamic trailer fittings than those in other parts of the country. ANNEX TABLE 6B-1 Observations Made on the Use of Aerodynamic Devices on 53+ Ft Dry or Refrigerated Vans Pulled by Sleeper Cab Tractors No. of trailers in Side Underbody Rear Trailer w/ Locationa Sample Skirts Fairings Fairing Device b CA, I-5, Sacramento, NB, SB 565 199 11 0 210 CA, I-10, 90 mi. E of LA, WB 1068 371 42 10 414 CA, I-15, 87 mi. E of LA, SB 944 392 55 8 450 CA, I-80, 93 mi. E of Sacramento, 497 206 15 2 216 WB AZ, I-10, 10 mi W of Phoenix, EB, 300 119 10 6 130 WB OR, I-84, 5 mi. E of Portland, EB, 100 23 1 1 24 WB TX, I-35, 30 mi. N of San Antonio, 215 45 4 3 49 NB, SB MI, I-94, 26 mi. west of Ann Arbor, 289 64 2 0 66 EB, WB PA, I-81, 29 mi, S of Harrisburg, 662 170 11 0 181 NB, SB MD, I-95, 25 mi. N of Washington 300 68 6 0 74 DC, NB SB NOTE: See note in text regarding the design of the observations. AZ = Arizona; CA = California; DC = District of Columbia; MD = Maryland; MI = Michigan; PA = Pennsylvania; and OR = Oregon. a WB, SB, and so on indicate the direction on the freeway surveyed. Some surveys were in only one direction. b Trailers using one or more devices. The sum of columns 3, 4 and 5 does not agree with the final column due to a small number of trucks using two devices. PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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Appendixes PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION

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