Truck manufacturers first began to develop more fuel-efficient vehicles in the 1970s
because of the energy crisis. Since that time, significant gains in efficiency have been made through improvements in aerodynamics, tire rolling resistance and engine performance. Manufacturers have enhanced tractor aerodynamics, for example, by streamlining the front profile and sloping the hood, utilizing aerodynamic bumpers and mirrors, and adding roof and side fairings. These changes have reduced the average drag coefficient (a measure of wind resistance) from 0.80 to 0.65 – a 20 percent improvement compared to more traditional tractor styling.[1] Other advances such as trailer aerodynamics, tire and engine improvements, use of alternative fuels and electric vehicles, innovative cargo management systems and higher productivity vehicles can also improve fuel efficiency and/or reduce emissions.
Further efficiency improvements were mandated for medium- and heavy-duty vehicles manufactured in 2014 and beyond. The U.S. Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) issued a joint rulemaking in 2011 that specified emissions and fuel consumption standards for truck-tractors, heavy-duty pickups and van and certain vocational vehicles.[2] Model year 2017 trucks meeting the final standards were estimated to reduce greenhouse gas (GHG) emissions and fuel consumption by as much as 20 percent compared to a model year 2010 truck.
A second phase of this program was enacted in 2016 that required additional reductions in GHG emissions and fuel consumption.[3] Trucks meeting these standards, which phase-in through model year 2027, will reduce GHG emissions and fuel consumption by an additional 25 percent.
After the adoption of the Phase 2 regulations, manufacturers have worked with EPA to update test procedures to ensure compatibility with the requirements. In 2021, EPA finalized changes to the test procedures as well as other amendments.[4]
Phase 3 regulations, enacted in 2024, stipulated more stringent GHG emissions standards than those set forth in Phase 2. The Phase 3 regulations revised the previous standards for model year 2027 vehicles and established more stringent annual emission reduction requirements through model year 2032. The standards were based on increasing sales of zero-emission vehicles. The new standards require model year 2032 trucks to reduce GHG emissions by up to 60 percent compared to the Phase 2 requirements for model year 2027 trucks.[5]
In 2025, EPA announced their formal reconsideration of the Phase 3 standards. Concerns including the economic burden imposed in regulatory and compliance costs were cited as rationale for reassessing the updated regulations.[6]
Truck tractors have become increasingly more aerodynamic with manufacturers analyzing design aspects ranging from windshield angles to sun visor shapes to improve efficiency. Several devices are currently available for improving tractor aerodynamics including roof fairings, gap reducers, aerodynamic bumpers and mirrors and fuel tank side fairings (see Figure 2.1).
Figure 2.1. Currently Available Aerodynamic Devices
Many of these devices are available as options on new tractor purchases or can be retrofitted on existing tractors. Research indicates a gap reducer may decrease fuel consumption by 2 to 3 percent at a cost of $700 to $1,000.[7] The National Research Council of Canada found that fender mirrors contribute approximately 1 to 2 percent of drag, while main mirrors were responsible for up to 3 percent of drag suggesting that reducing mirror size, changing their location, or replacing mirrors with low-drag camera-based rearview systems can provide measurable energy savings.[8]
While significant fuel efficiency improvements can be made through increasing tractor aerodynamics, changes made to the trailer can yield additional gains. EPA’s SmartWay Partnership, for example, has researched the impact of several trailer modifications, including side fairings (also known as “skirts”), which are attached to the lower edge of each trailer side between the axles and trailer tails (also known as “boat tails” or “base flaps”) which are attached to the rear door of the trailer (refer to Figure 2.1).
Trailer side fairings typically range in cost from $700 to $1,100 and have been estimated to improve fuel economy by 3 to 7 percent.[9] Side fairings are more commonly used in higher speed, long-haul operations since they can be less effective and have greater potential for damage in lower speed, urban environments. Trailer tails are another option, ranging in cost from $1,000 to $1,600 while having the potential to improve fuel economy by 3 to 5 percent. [10] The EPA found that a combination of multiple trailer fairings (including a combination of front, side, rear, and/or under trailer) which have been SmartWay verified were able to produce fuel savings of 9 percent or greater.[11]
Another important factor in truck fuel efficiency is tires. Tire rolling resistance accounts for approximately 30 percent of the energy required to move a line-haul truck on level roads and at highway speeds.[12] There are two types of low rolling resistance (LRR) options that reduce rolling resistance while providing fuel and emissions reduction benefits – tires and retreads.[13]
Low Rolling Resistance Tires. LLR tires are designed to minimize the friction
between the roadway and tire. Specific features may include slightly thinner sidewalls, shallower tread depths and low rolling resistance tread compounds. An ATRI survey found LRR dual tires to be one of the most common fuel saving technologies – used by more than 75 percent of survey respondents.[14] EPA has demonstrated that certain LRR tires and retread technologies can reduce both costs and emissions for long-haul class 8 tractor-trailers by 3 percent or more.[15] The approximate per tire cost is typically slightly higher than conventional tires.[16] Due to the potential for faster tread wear-out, purchasers need to evaluate the cost-benefits of increased tire costs versus lower fuel costs.
Retread Technologies. Retread technologies fall into two categories: mold and precure. Both categories can be used on two of the three axle positions: trailer and drive.[17] Mold cure retreading involves applying non-vulcanized rubber tread directly to the top of the buffed tire before being placed into a mold which is then heated so that the rubber within the mold adheres to the tire completely.[18] The precure style of retreading involves using rubber, which has already been vulcanized, with a new tread design. A thin layer of cushioned gum is placed on the area of a newly buffed tire to act as a bond to attach a new layer of precured tread which is ultimately placed directly within a curing chamber to complete the adhering.[19]
Single-Wide Tires. Single-wide tires (also known as “wide-base” or “super-singles”) can offer fuel economy benefits ranging from 3 to 18 percent over LRR dual tires.[20] However, in recent years LRR have considerably improved, thereby decreasing the fuel efficiency gap between single-wide tires and LRR dual tires. For example, instances of LRR dual tires outperforming single-wide tires have been documented. Single-wide tires use a single rim with only two sidewalls to replace the conventional dual tire configuration which utilizes two complete tires (i.e. two rims and four sidewalls). Single-wide tires therefore offer the added benefit of weight savings. One study found a five-axle tractor-trailer combination that was equipped with single-wide tires and aluminum rims (which are lighter than standard steel rims) can reduce weight by 800 to 1,400 pounds.[21] Switching to single-wide tires and reducing vehicle weight by 1,000 pounds could ostensibly lead to an additional 1,000 pounds of product with the same fuel efficiency. Furthermore, reducing vehicle weight by 1,000 pounds resulted in fuel savings of about 0.8 percent.[22] This research also found that one reason fleets chose not to test wide-base tires was the high upfront cost of purchasing the tire and wheel.
Tire Pressure Systems. Under-inflated tires can significantly increase rolling resistance, thus increasing fuel consumption. One study revealed that around 20 percent of trucks are operating with one or more tires under-inflated by at least 20 PSI, underscoring the need for tire pressure systems.[23] The Federal Motor Carrier Safety Administration evaluated the effectiveness of tire pressure monitoring systems (TPMS) and automatic tire inflation systems (ATIS).[24] The two motor carriers involved in the field test reported a fuel economy increase of 1.4 percent using the systems. The payback period for TPMS, which have a cost of approximately $1,800 per tractor-trailer, was found to range from less than 14 months to less than 6 months for a high-mileage fleet.[25] Another report found reliability to be the number one criterion among fleets when selecting tire pressure systems since downtime negates the efficiency improvement.[26] The market penetration of ATIS in new trailers has proliferated in recent years, with more than 70 percent of model year 2018 trailers equipped with ATIS.[27]
Diesel engines are significantly more fuel efficient than gasoline engines and most large, heavy-duty truck engines are designed to run on diesel fuel. As a result of engine improvements and cleaner fuels, diesel engines today produce 99 percent fewer emissions of nitrogen oxides and particulate matter when compared to earlier versions of these engines.[28]
There are currently several different technologies available that can be used to increase engine efficiency and/or reduce emissions, including (but not limited to):[29]
- Turbocharging– An exhaust-driven turbine drives a compressor to increase the air density going into the engine.
- Electrification of engine accessories– Traditional belt- or gear-driven accessories can be converted to electric power.
- Reduction of engine friction– Engine friction reduction has been pursued continuously by manufacturers through careful design and selection of advanced materials.
- Improvement of diesel exhaust particulate matter (PM) control using a diesel particulate filter (DPF) with a catalyst coating– The use of a DPF can degrade the fuel efficiency of the engine owing to exhaust flow restriction and pressure buildup in the system or the need for additional fuel to maintain the operation of the DPF. The use of catalyst coatings can help promote oxidation and reduce the need for additional fuel.
- Improvement of diesel exhaust catalytic system efficiencies using selective catalytic reduction (SCR)– Control of nitrogen oxide (NOx) has been accomplished with cooled exhaust gas recirculation (EGR) and an SCR catalyst.
- Improved driveline efficiency– New automated mechanical and automatic transmissions have been shown to improve fuel economy resulting in lower emissions.
Federal regulations have played a key role in the advancement of engine technologies. More stringent engine emissions standards for heavy-duty trucks have been phased-in several times including in 2004 (pulled ahead to 2002 for most manufacturers), 2007, 2010, 2014, 2017, 2021, and 2024. While these mandates progressively decreased allowable emissions from truck engines, average fuel economy for combination trucks peaked in the late 1990s and has only recently surpassed these levels.[30]
The Phase 1 and 2 GHG emissions and fuel consumption standards for medium- and heavy-duty vehicles have contributed to improved fuel economy and represent the federal government’s efforts to mandate reductions in GHG emissions and fuel consumption from trucks.[31]
Alternative fuels are another option for reducing emissions and the consumption of petroleum products by making fuels from sources other than petroleum. With medium and heavy-duty fleets comprised largely of diesel engines, renewable diesel and biodiesel blends are viable drop-in alternative fuel options. Natural gas, in compressed (CNG) and liquefied (LNG) forms, are other options although a spark ignition, rather than compression ignition, engine is required. The typical driving range of a vehicle is a key factor in determining the most appropriate alternative fuel. For example, CNG may be a suitable option for port drayage, city refuse haulers and local delivery trucks since these trucks tend to operate in closer proximity to their refueling stations.
Renewables
Renewable Diesel. Renewable diesel is a biofuel made from vegetable oil and fats that is chemically identical to petroleum diesel.[32] Renewable diesel meets the Advancing Standards Transforming Markets (ASTM) specification for petroleum diesel; thus, it can be used as a drop-in fuel and diesel engine can operate 100 percent on renewable diesel. It should be noted that renewable diesel is often confused with biodiesel, which is a distinct, chemically different fuel that must be mixed in limited proportions with petroleum diesel.
Consumption of renewable diesel surpassed biodiesel in 2022, with renewable diesel consumption increasing by more than 700 percent from 2018 to 2024.[33] ATRI research compared life-cycle CO2 emissions from trucks running on renewable diesel to battery electric trucks, with petroleum diesel trucks serving as the baseline. The analysis found that trucks using renewable diesel produce fewer life-cycle CO2 emissions (67% reduction compared to petroleum diesel) than battery electric trucks (30% reduction compared to petroleum diesel).[34]
Biodiesel. Biodiesel is generally manufactured from vegetable oil or fats, with the majority produced from soybeans, and is available in its pure form (B100) as well as blended with petroleum-based diesel, typically at 2 percent (B2) to 20 percent (B20) ratios. Use of this renewable fuel in its blended form can reduce diesel consumption and most tailpipe emissions without the need to modify the engine. While most major engine manufacturers support using biodiesel blends up to B20, some do not recommend blends above B5 in certain on-highway vehicles.[35] Additionally, cold weather performance, fuel filter clogging, fuel quality, NOx emissions, and microbial growth are issues which must be considered when using biodiesel or biodiesel blends.[36]
Biodiesel typically costs more at the pump and on an energy equivalent basis than diesel. In January 2025, B20 cost $0.15 less than diesel with B99-100 costing $0.78 more per DGE. [37] Similarly, renewable diesel generally costs more to produce than petroleum diesel fuel.[38] While the future production levels and price of biodiesel and renewable diesel are uncertain, requirements mandating minimum volumes of these transportation fuels under the federal Renewable Fuel Standard combined with incentives continue to advance their use among motor fuel consumers.
Overall, the primary barriers to increased adoption of alternative fuels by the trucking industry are fuel availability, and in some cases, higher vehicle acquisition costs. If on-site natural gas fueling infrastructure is necessary (which can range from $1 to $4 million), the initial expense can be prohibitive.[39] Additional costs can be especially restrictive to smaller fleets and owner-operators that have limited access to the financial capital necessary to purchase more expensive equipment or fuel. As of April 2025, nearly half of the nation’s public and private LNG stations were located in three states, California, New York, and Texas.[40] Additionally, more than 60 percent of the nation’s public and private fueling stations selling either CNG or biodiesel were found in nine states.[41] For truck fleets that have irregular routes, this limited fueling infrastructure is a major constraint to the advancement of alternative fuels.
CNG and LNG. Discoveries of large natural gas reserves across the U.S. have led to relatively low natural gas prices. However, natural gas prices reached their highest level in 20 years in February 2022 spurred by 179 percent 30-day volatility. This increase was driven by a myriad of factors, including frozen production wells and pipeline outages.[42] By January 2025, the average retail cost of a gallon of diesel fuel was $3.55 compared to an LNG diesel gallon equivalent (DGE) of $4.86 and a CNG DGE of $3.37.[43]
While natural gas can be an attractive option, the business case for fleet operators varies and depends on several key factors to make the business case positive, including full utilization of fueling stations, utilizing both medium- and heavy-duty trucks, and taking advantage of all incentives (Low Carbon Fuel Standard and Renewable Identification Numbers. [44]
Research has found that natural gas trucks deliver a 5 to 18 percent reduction in lifetime GHG emissions compared to diesel trucks.[45] On a per gallon basis, ATRI research found that replacing petroleum diesel with LNG reduced life-cycle CO2 emissions by 27.8 percent.[46]
It should be noted that most natural gas is a fossil fuel rather than a renewable fuel. However, some natural gas can be produced from renewable sources, such as landfill gas or waste products. Landfill gas achieves an estimated life-cycle GHG emission reduction as high as 93 percent when it replaces diesel fuel while waste gas can achieve credit for avoided life-cycle emissions, in some cases. While these sources provide an opportunity for even greater reductions in GHG emissions, they are less abundant and can be more difficult to capture efficiently. In addition, natural gas trucks are typically less fuel efficient. The spark ignition engine used to power these trucks is roughly 15 less efficient than a diesel counterpart.[47]
In contrast to the price of CNG, the additional incremental cost of a natural gas truck has been estimated to range from $17,500 for a Class 5 walk-in van to $90,000 for a Class 8 sleeper cab when compared to their diesel counterparts.[48] Few subsidies are available to offset this incremental cost, leaving buyers dependent upon future fuel cost savings to offset the higher purchase price. Although there are limited data, Class 8 CNG tractors have demonstrated operation and maintenance costs around $0.10/mile.[49] For Class 8 diesel tractors, O&M costs show a small spread, typically in the $0.12–$0.19/mile range.
Refueling locations, fuel venting and handling, and facility adaptation are additional issues that must be considered. Another factor is the uncertainty of energy markets. With pronounced volatility in natural gas prices in 2022 and market forecasts predicting rising natural gas prices, the future price of natural gas is another factor to evaluate.[50] Clearly, natural gas increasing in price will extend the payback period for CNG and LNG trucks.
Despite these challenges, several large motor carriers have purchased natural gas-fueled vehicles in recent years.[51] In 2022, ATRI estimated 175,000 natural gas vehicles in operation in the U.S., with the majority being commercial vehicles in the transit, refuse, and medium- and heavy-duty truck sectors.[52] In 2024, overall fleet demand for natural gas fuel grew; however, the growth appears to be primarily caused by an increased demand from fleets that already have natural gas trucks, rather than by fleets adopting them for the first time.[53] Fleets that travel “point-to-point” or round-trip routes in operations such as waste collection and local delivery have been using natural gas for years.
Hydrogen Internal Combustion Engines. Hydrogen-powered internal combustion engines (ICE) can offer a significant reduction in GHG emissions compared to traditional diesel ICEs. According to the Southwest Research Institute, converting petroleum fuel trucks to hydrogen ICE could eliminate nearly all tailpipe CO2 emissions.[54] Life-cycle emissions of hydrogen, however, vary depending upon how it is produced.[55] Hydrogen ICE engines use spark-ignition technology which require less costly emission control systems.[56] Production and infrastructure for transportation users is currently limited which contributes to higher costs for hydrogen. Although some projections estimate that hydrogen ICE trucks will be 50 percent more expensive to own and operate than diesel trucks by 2030, this estimate is largely based on the projected high cost of hydrogen fuel.[57] Separate research found that, compared to battery-electric vehicles and fuel-cell electric vehicles, hydrogen ICE trucks were the most cost efficient alternative powertrain option for long-haul freight applications under various electricity and hydrogen pricing scenarios.[58]
In addition to the conventional powertrains found on trucks with internal combustion engines, alternative powertrains have emerged. These alternatives include hybrid electric vehicles (HEVs), battery-electric vehicles (BEVs) and fuel-cell electric vehicles (FCEVs) which are discussed in more detail below.
Battery Electric Vehicles. Battery electric vehicles (BEVs) rely on onboard battery storage to provide the electricity used to power one or more electric motors. BEVs need to be plugged into an electric charger to refuel, thus either depot charging or a network of charging stations is needed. ATRI estimates a total cost of more than $35 billion to install charging stations across the nation’s truck parking locations.[59] In addition, adequate onboard battery storage capacity is needed to match the vehicle’s mileage needs between refueling.
Currently, Class 8 BEVs have reported maximum ranges of 125 to 275 miles, which is significantly less than their diesel truck counterparts.[60] Researchers analyzed the feasibility of BEVs in long-haul scenarios, assuming adequate charging infrastructure. They found that charging times alone extended trip durations by 16 to 32 percent when compared to diesel trucks.[61] Even with sufficient charging infrastructure, the current BEV range limitations pose significant operational challenges, especially in long-haul trucking.
There are several resources available which discuss various aspects of this emerging technology, including EPA’s SmartWay program which offers several resources ranging from total cost of ownership calculators to technology readiness evaluations.[62] In addition, vehicle availability is evolving with more models and applications becoming available.[63] How BEVs integrate into the commercial vehicle fleet is still to be determined. One analysis assumes BEVs will be best for shorter-range applications or when dwell time is not a concern and fuel cell powertrains will be used for longer ranges or operating scenarios that require higher uptime.[64]
Fuel Cell Electric Vehicles. Fuel cell electric vehicles (FCEVs) operate like BEVs; however, their energy is generated onboard the vehicle via electricity produced by a fuel cell. Fuel cells produce electricity through a chemical reaction, generally involving hydrogen. The electricity generated by the fuel cell is transferred to an electric battery which powers one or more electrical motors. Only water vapor is emitted from the tailpipe.[65] Hydrogen’s energy yield is 122 kilojoules per gram, which equates to 2.75 times more energy than fossil fuels.[66] The overall market outlook for hydrogen powered FCEVs is bullish, with the 2024 market value of approximately $140 million expected to grow to $5.8 billion by 2034.[67]
FCEVs face similar challenges as natural gas vehicles and BEVs: fueling infrastructure and a high initial purchase cost.[68] Truck manufacturers are targeting a range of roughly 500 miles, although an 1,800 miles single fill trip has been demonstrated.[69] While hydrogen is currently being used by trucks in gaseous form, research is currently being conducted on using it in liquid form. As a liquid, hydrogen is twice as dense as its gaseous state and can take a vehicle nearly twice the distance as gaseous hydrogen.
How hydrogen is produced factors into the fuel’s overall life-cycle emissions. Hydrogen produced from coal or methane – black, brown, or gray hydrogen – is considered less climate-friendly.[70] Hydrogen produced using carbon capture or clean electricity – blue or green hydrogen – is considered more climate-friendly however these technologies further add to the cost of the fuel.
Hybrid Electric Vehicles. Hybrid electric vehicles are used primarily in package and beverage delivery fleets. These vehicles provide increased fuel efficiency and air quality benefits. The cost of a hybrid heavy-duty truck can be as much as $60,000 more than a comparable diesel truck.[71] Since these vehicles tend to be used in urban operations, overall mileage and fuel usage may be lower and require a longer payback period to offset the higher initial cost.
FedEx has been using hybrid electric trucks for urban deliveries for several years. In 2012, the company reported improving the fuel efficiency of its vehicle fleet by nearly 20 percent over a five-year period, in part, through the operation of 364 hybrid electric vehicles.[72] UPS has also deployed nearly 400 hybrid electric vehicles that have improved fuel economy by 35 percent compared to the trucks that were replaced.[73] As of 2022, UPS uses more than 1,000 electric and hybrid electric vehicles. [74]
More efficient utilization of trailer space, whether through reduced empty trailer miles or strategic trailer loading, can further improve a fleet’s productivity. According to ATRI research, approximately 16 percent of for-hire fleet miles in 2023 were non-revenue or “empty” miles.[75]
For a typical long-haul truck traveling 100,000 miles per year, this averages approximately 16,000 non-revenue producing miles annually while consuming nearly 2,400 gallons of fuel. Assuming a diesel fuel price of $3.55 per gallon, non-revenue fuel costs would be more than $8,400 annually.[76] In 2017, empty miles were estimated to account for roughly 74.2 million metric tons of GHG emissions in the United States. [77] As shown, matching freight demand to available capacity can be an important practice for saving fuel, lowering operating costs, and benefiting the environment through reduced emissions.
The American Council for an Energy Efficiency Economy (ACEEE) asserts that the average load factor, a measure of a truck’s utilization when loaded, is 57 percent. Improvements in trailer capacity can reduce unnecessary emissions and improve operational efficiency.[78]
The Centre for Data and Analysis in Transportation studied the use of electronic vehicle management systems (EVMS) to improve trailer capacity utilization in Canada. Such systems are intended to match available freight capacity with demand for freight services from shippers.[79] The research found a 16 percent increase in the capacity utilization of trucks using EVMS.
In the U.S., the Federal Highway Administration’s (FHWA) Cross-Town Improvement Project (C-TIP) developed methods to reduce the number of empty trailers moving between terminals in Kansas City by better coordinating cross-town truck traffic. C-TIP utilized several technologies to accomplish this, including real-time traffic monitoring, dynamic route guidance, chassis utilization tracking and wireless drayage updating. A pilot test of the wireless drayage updating system demonstrated a 13 percent reduction in empty trailer trips, saving a modest 121 gallons of fuel for the participating carriers over a 2-month period.[80] According to FHWA, the cost of this type of service is expected to be low. A similar pilot test conducted in Chicago over four months in 2011 resulted in a 52 percent reduction in empty trailer movements.[81] Combined, these systems have the potential not only to help carriers increase productivity through better asset management, but to reduce congestion levels in the surrounding areas.
Motor carriers also rely on a variety of private systems to match freight demand to truck availability. One fleet found improvements in data accuracy allowed them to further build out loads.[82] Further, the emergence of load boards, which use the internet and/or cell phones to match freight loads to truck availability, is another practice that is reducing empty miles.
A 2021 report from ACEEE documented innovative information and communication technologies (ICT) that reduced empty miles. One artificial intelligence-powered freight matching software achieved an estimated 45 percent reduction in emissions by reducing empty miles. Another algorithmic freight bundling ICT minimized empty miles by approximately 22 percent.[83]
Transponders, including radio frequency identification devices (RFID) tags, can be used alongside cell phones to optimize cargo management. Transponders monitor and track the location of trailers, intermodal containers, and cargo in real-time. These devices also allow the identification of trucks to bypass weight stations, tolls plaza and security check points.
Companies that operate their own fleet of trucks to support their primary business (i.e., private fleets) may be able to maximize their utilization of trailer space with compact packaging and innovative loading techniques. For example, Walmart found that the use of a two-step safety stool increased trailer fills by nearly 3 percent.[84] In addition, a new load designer system in their grocery operations identifies unused space and more accurately designates pallet positions for optimal loading/off-loading.
Other examples of strategic loading include mixing items with high and low weights to balance space and weight limitations. Some carriers have been able to increase the number of pallets loaded onto a trailer using a technique called “pin-wheeling” (i.e. turning every other pallet by 90 degrees). Research found this technique resulted in an additional two pallets in a standard trailer.[85] As shown by these examples, cargo management systems encompass a broad range of technologies and practices and continue to emerge as an important component of the sustainable practices being used by the trucking industry.
Another way of improving fuel efficiency and reducing emissions is using higher productivity vehicles (HPVs). HPVs operate at heavier weights and/or longer lengths than traditional vehicle configurations. Several studies have found HPVs to be more efficient at moving freight.
Among the three countries participating in the United States-Mexico-Canda Agreement (USMCA), the United States has the lowest gross vehicle weight (GVW) limit.[86] In the U.S., trucks are generally limited to an overall GVW limit of 80,000 pounds and typically use a single trailer that is 53 feet in length or less or two trailers of 28 feet or less.[87] As shown in Figure 2.2, several states allow HPVs to operate on portions of the national highway system (NHS) without special permitting (but under certain restrictions). These states have been granted “grandfather rights” by the U.S. Congress which allow the operation of vehicles at weights and lengths greater than the current federal limits.
Figure 2.2. Permitted Longer Combination Vehicles on the National Highway System: 2017 [88]
Examples of HPVs in use today include a six-axle tractor-semitrailer, a Rocky Mountain double, a triple trailer combination and a turnpike double as shown in Figure 2.3.
Figure 2.3. Common Higher Productivity Vehicle Configurations
Over several decades, states, motor carriers, shippers and other stakeholders have proposed changes to the federal truck size and weight limits and several states have sought exemptions from the federal limit to expand the HPV network. In late 2009, Congress approved a bill (H.R. 2112) that created a pilot program in Maine and Vermont allowing 108,000 to 120,000-pound six-axle trucks to operate on Interstate highways in Vermont and 100,000-pound six-axle trucks on Interstate highways in Maine. The benefits of the program were illustrated by Champlain Oil Company, which saved 43,400 gallons of diesel fuel and traveled 320,000 fewer miles during the one-year program.[89] While the pilot program expired in December 2010, legislation that exempted the Maine and Vermont Interstate highways from federal vehicle weight limits for a 20-year period was signed into law in November 2011.[90]
In the ATRI report Energy and Emissions Impacts of Operating Higher Productivity Vehicles, Update 2008, researchers quantified the energy and emissions impacts that can result from operating trucks at various weights and configurations. [91] Six common vehicle configurations were modeled through this research over a typical route to estimate fuel consumption and emissions. Increases in fuel efficiency were observed for nearly every HPV configuration evaluated. As an example, vehicles operating at 120,000 pounds GVW had fuel efficiency increases that ranged from 15 to 31 percent while increases of 33 percent were observed for vehicles operating at 140,000 pounds GVW.
In Canada, the Ontario Ministry of Transportation, after initiating a pilot program to evaluate longer combination vehicle (LCV) operations, now allows a limited number of LCVs on designated Ontario highways.[92] The program reports that each LCV uses approximately one-third less fuel than the two tractor-trailers it replaced. It also estimates that, in a typical year, LCVs eliminated 9 million tons of greenhouse gases.
A Canadian Trucking Alliance report documents the potential benefits of HPV operations in the provinces of Quebec, Alberta, Manitoba and Saskatchewan.[93] The focus of this research was the turnpike double (a Class 7 or 8 tractor pulling two semitrailers) and researchers collected actual fuel consumption data from carriers. The findings were consistent with previous research that found HPVs can yield fuel consumption savings of 30 percent or more.
Furthermore, in a study commissioned by Alberta Infrastructure, researchers found that HPVs were significantly more efficient than conventional tractor-trailer combinations.[94] The use of HPVs (at a GVW of 62,500 kg and a length of 37 m or approximately 137,800 lbs. and 121 ft.) within the Alberta province has saved shippers approximately C$40 million annually and reduced traffic levels by nearly 44 percent.[95] Across the study network, the annual diesel fuel consumed by trucks has been reduced by 32 percent through the use of HPVs, which equates to an annual fuel savings of approximately 4 million gallons.[96]
Another country that studies HPVs is Australia. The Transport Certification of Australia currently implements two HPV monitoring schemes: Telematics Monitoring Application (TMA) and Intelligent Access Program (IAP). Both schemes are administered by the Victoria Department of Transport to permit access of eligible HPVs on approved roads.[97] Data is collected from smart on-board mass systems and standardized to enable new productivity and safety initiatives using a National Telematics Framework.[98] As of Q1 2021 all HPVs will be required to have a Smart OBM system fitted and be enrolled in either IAP or TMA.
In the United States, FHWA examined potential changes to the federal truck size and weight limits through its 2000 Comprehensive Truck Size and Weight Study.[99] The study outlines several scenarios where potential changes in truck size and weight could be made; the outcome of the four HPV scenarios were decreases in total truck vehicle miles traveled (VMT) ranging from 10.6 to 23.2 percent and decreases in energy costs of 6.2 to 13.8 percent.
Changes in federal law are the key to the increased deployment of HPVs. The surface transportation authorization bill, Moving Ahead for Progress in the 21st Century (MAP 21 – 2012), included provisions for a two-year study on the impacts of increased truck sizes and weights. [100] The study, which was released in April 2016, analyzed five focus areas: 1) modal shift, 2) safety, 3) pavement, 4) bridges, and 5) compliance. While the study identified potential impacts if changes were made to trucks sizes and weights, it did not make any policy recommendations.
Since some states currently allow twin 33-foot trailers, several motor carriers have already evaluated their performance. Based on data supplied by FedEx, ABF System, Con-way, Estes Express, Old Dominion Freight Line, UPS and YRC Worldwide, the industry could absorb up to 18 percent of future freight growth without any change in gross vehicle weight or additional miles traveled if the standard for twin trailers was increased to 33-feet.[101]
[1] U.S. EPA, “Improved Aerodynamics: A Glance at Clean Freight Strategies” (accessed on May 28, 2025), SmartWay Transport Partnership, https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P100XM9X.txt.
[2] EPA, “EPA and NHTSA Adopt First-ever Program to Reduce Greenhouse Gas Emissions and Improve Fuel Efficiency of Medium- and Heavy-duty Vehicles” (2011), https://www.epa.gov/regulations-emissions-vehicles-and-engines/final-rule-phase-1-greenhouse-gas-emissions-standards-and.
[3] U.S. EPA, “Final Rule for Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles – Phase 2” (October 2016), https://www.epa.gov/regulations-emissions-vehicles-and-engines/final-rule-phase-2-greenhouse-gas-emissions-standards.
[4] U.S. EPA, “Improvements for Heavy-Duty Engine and Vehicle Test Procedures, and Other Technical Amendments” (accessed on May 28, 2025), https://www.govinfo.gov/content/pkg/FR-2021-06-29/pdf/2021-05306.pdf.
[5] U.S. EPA, “Final Rule: Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles – Phase 3” (March 2024), https://www.epa.gov/regulations-emissions-vehicles-and-engines/final-rule-greenhouse-gas-emissions-standards-heavy-duty.
[6] U.S. EPA, “EPA Announces Action to Implement POTUS’s Termination of Biden-Harris Electric Vehicle Mandate” (March 2025), https://www.epa.gov/newsreleases/epa-announces-action-implement-potuss-termination-biden-harris-electric-vehicle.
[7] Committee to Assess Fuel Economy Technologies for Medium- and Heavy-Duty Vehicles, National Research Council, “Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles” (2010), Transportation Research Board pp 133-138, https://nap.nationalacademies.org/catalog/12845/technologies-and-approaches-to-reducing-the-fuel-consumption-of-medium-and-heavy-duty-vehicles; NACFE, “Confidence Report: Trailer Aerodynamics” (August 12, 2020), https://nacfe.org/research/technology/trailer-aerodynamics/.
[8] Brian McAuliffe, Faegheh Ghorbanishohrat, and Hali Barber, “Preliminary Investigation Towards Next Generation Truck Design for Aerodynamic Efficiency” (July 4, 2022), National Research Council Canada, https://nrc-publications.canada.ca/eng/view/object/?id=610b10b1-805a-4047-a908-174b18a0ea07; North American Council for Freight Efficiency “Confidence Report on Trailer Aerodynamic Device Solutions” (2016).
[9] North American Council for Freight Efficiency, “Confidence Report on Trailer Aerodynamic Device Solutions” (2020), https://nacfe.org/research/technology/trailer-aerodynamics/.
[10] Ibid.
[11] U.S. EPA, “SmartWay-verified Aerodynamic Technologies” (accessed on May 22, 2025), SmartWay, https://www.epa.gov/sites/default/files/2016-03/documents/420f15006.pdf.
[12] National Research Council, “Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two” (2014), Transportation Research Board, , http://www.nap.edu/catalog.php?record_id=18736.
[13] U.S. EPA, “Learn About Low Rolling Resistance (LRR) New and Retread Tire Technologies” (accessed on May 22, 2025), https://www.epa.gov/verified-diesel-tech/learn-about-low-rolling-resistance-lrr-new-and-retread-tire-technologies.
[14] Brandon Schoettle, Michael Sivak, and Mike Tunnell, A Survey of Fuel Economy and Fuel Usage by Heavy-Duty Fleets, ATRI (October 2016), https://truckingresearch.org/2016/10/17/a-survey-of-fuel-economy-and-fuel-usage-by-heavy-duty-truck-fleets/.
[15] Ibid.
[16] North American Council for Freight Efficiency, “Confidence Report: Low Rolling Resistance Tires” (2020), https://nacfe.org/wp-content/uploads/2018/01/TE.org_LRRD_full_report-.pdf.
[17] Ibid.
[18] Service Tire Truck Centers, “Mold Cure vs. Pre Cure: What’s the Difference Between the Two Tire Retreading Styles?” (August 18, 2018), https://www.sttc.com/mold-cure-vs-pre-cure-tire-retreading-styles/.
[19] Ibid.
[20] Ibid.
[21] Ibid.
[22] Ibid.
[23] North American Council for Freight Efficiency, “Confidence Report: Tire Pressure Systems” (2020), https://nacfe.org/wp-content/uploads/2020/05/Tire-Pressure-Systems-Confidence-Report-Executive-Summary2020.pdf.
[24] FMCSA, “Advanced Sensors and Applications: Commercial Motor Vehicle Tire Pressure Monitoring and Maintenance” (February 2014). https://rosap.ntl.bts.gov/view/dot/178
[25] TruckX, “How Much Does it Cost to Replace a TPMS Sensor” (accessed on May 28, 2025), https://truckx.com/faqs/fleet-management/how-much-does-it-cost-to-replace-a-tpms-sensor/.
[26] Ibid.
[27] Ibid.
[28] U.S EPA, “Accomplishments and Successes of Reducing Air Pollution from Transportation in the United States” (accessed on May 28, 2025), https://www.epa.gov/transportation-air-pollution-and-climate-change/accomplishments-and-successes-reducing-air.
[29] National Research Council, Transportation Research Board, “Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two” (2014), http://www.nap.edu/catalog.php?record_id=18736.
[30] FHWA, “1997 Highway Statistics Series Table VM-1” (accessed on May 28, 2025), https://www.fhwa.dot.gov/ohim/hs97/roads.htm; FHWA, “2020 Highway Statistics Series Table VM-1” (accessed on May 28, 2025).
[31] EPA, “EPA and NHTSA Adopt First-ever Program to Reduce Greenhouse Gas Emissions and Improve Fuel Efficiency of Medium- and Heavy-duty Vehicles” (2011), https://www.epa.gov/regulations-emissions-vehicles-and-engines/final-rule-phase-1-greenhouse-gas-emissions-standards-and; U.S. EPA, “Final Rule for Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles – Phase 2” (October 2016), https://www.epa.gov/regulations-emissions-vehicles-and-engines/final-rule-phase-2-greenhouse-gas-emissions-standards; U.S. EPA, “Final Rule: Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles – Phase 3” (March 2024), https://www.epa.gov/regulations-emissions-vehicles-and-engines/final-rule-greenhouse-gas-emissions-standards-heavy-duty.
[32] U.S. DOE, “Hydrogenation-Derived Renewable Diesel” (accessed on May 22, 2025), Alternative Fuels Data Center, http://www.afdc.energy.gov/fuels/emerging_green.html.
[33] U.S. EIA, “May 2025 Monthly Energy Review” (June 23, 2025), https://www.eia.gov/totalenergy/data/monthly/pdf/mer.pdf.
[34] Jeffrey Short, Renewable Diesel – A Catalyst for Decarbonization (April 2024), ATRI, https://truckingresearch.org/2024/04/renewable-diesel-a-catalyst-for-decarbonization/.
[35] Clean Fuels Alliance America, “OEM Positions on Biodiesel and Renewable Diesel” (January 2025), https://cleanfuels.org/wp-content/uploads/OEM-Support-Summary_Jan-2025.pdf.
[36] National Renewable Energy Laboratory, “Biodiesel Handling and Use Guide” (2009), https://www.nrel.gov/docs/fy09osti/43672.pdf.
[37] U.S. DOE, “National Average Retail Fuel Prices on an Energy-Equivalent Basis, January 2025” (January 2025), https://afdc.energy.gov/fuels/prices.html.
[38] A. Milbrandt, C. Kinchin, and R. McCormick, “The Feasibility of Producing and Using Biomass-Based Diesel and Jet Fuels in the United States” (December 2013), National Renewable Energy Laboratory, https://docs.nrel.gov/docs/fy14osti/58015.pdf.
[39] U.S. DOE, “Natural Gas Fueling Infrastructure Development” (accessed on May 22, 2025), Alternative Fuels Data Center, http://www.afdc.energy.gov/fuels/natural_gas_infrastructure.html.
[40] U.S. DOE, “Alternative Fueling Station Total Counts by State and Fuel Type” (accessed on May 22, 2025), Alternative Fuels Data Center, http://www.afdc.energy.gov/afdc/fuels/stations_counts.html.
[41] U.S. DOE (2025), “Alternative Fueling Station Counts by State” (accessed on May 22, 2025), https://afdc.energy.gov/stations/states?count=total&include_temporarily_unavailable=false&date=.
[42] U.S. EIA, “U.S. Natural Gas Price Saw Record Volatility in the First Quarter of 2022” (2022), https://www.eia.gov/todayinenergy/detail.php?id=53579.
[43] U.S. DOE, “National Average Retail Fuel Prices on an Energy-Equivalent Basis, January 2025” (January 2025), https://afdc.energy.gov/fuels/prices.html.
[44] North American Council for Freight Efficiency, “Natural Gas’ Role in Decarbonizing Trucking” (March 25, 2024), https://nacfe.org/wp-content/uploads/2024/03/Nat-Gas-2024-Confidence-Report.pdf.
[45] Adrian O’Connell, Nikita Pavlenko, Georg Bieker, and Stephanie Searle, “A Comparison of the Life-Cycle Greenhouse Gas Emissions of European Heavy-Duty Vehicles and Fuels” (2023), The International Council of Clean Transportation, https://theicct.org/wp-content/uploads/2023/02/Lifecycle-assessment-EU-HDVs_final2.pdf.
[46] Jeffrey Short and Danielle Crownover, Understanding the CO2 Impacts of Zero-Emission Trucks: A Comparative Life-Cycle Analysis of Battery Electric, Hydrogen Fuel Cell and Traditional Diesel Trucks (May 2022), ATRI, https://truckingresearch.org/2022/05/understanding-the-co2-impacts-of-zero-emission-trucks/.
[47] National Research Council, “Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two” (2014), Transportation Research Board, https://nap.nationalacademies.org/catalog/18736/reducing-the-fuel-consumption-and-greenhouse-gas-emissions-of-medium-and-heavy-duty-vehicles-phase-two.
[48] California Air Resources Board, Draft Advanced Clean Fleets Total Cost of Ownership Discussion Document (September 9, 2021), https://ww2.arb.ca.gov/sites/default/files/2021-08/210909costdoc_ADA.pdf.
[49] Chad Hunter et al., “Spatial and Temporal Analysis of the Total Cost of Ownership for Class 8 Tractors and Class 4 Parcel Delivery Trucks” (September 2021), https://www.nrel.gov/docs/fy21osti/71796.pdf.
[50] U.S. EIA, “Short Term Energy Outlook: Natural Gas” (April 2025), https://www.eia.gov/outlooks/steo/report/natgas.php.
[51] Gladstein, Neandross & Associates (GNA), “State of Sustainable Fleets 2021 Market and Trends Brief”, (May 2021), http://www.StateofSustainableFleets.com.
[52] Jeffrey Short and Danielle Crownover, Understanding the CO2 Impacts of Zero-Emission Trucks: A Comparative Life-Cycle Analysis of Battery Electric, Hydrogen Fuel Cell and Traditional Diesel Trucks (May 2022), ATRI, https://truckingresearch.org/2022/05/understanding-the-co2-impacts-of-zero-emission-trucks/.
[53] TRC Companies, INC. (TRC) “State of Sustainable Fleets 2024 Market Brief” (May 2024), https://cdn.stateofsustainablefleets.com/2024/state-of-sustainable-fleets-2024-market-brief.pdf.
[54] Southwest Research Institute, “Hydrogen Internal Combustion Engine 2 (H2-ICE2) Consortium” (accessed on May 22, 2025), https://www.swri.org/markets/automotive-transportation/automotive/hydrogen-powered-vehicles/hydrogen-internal-combustion-engine-2-h2-ice2-consortium.
[55] Massachusetts Institute of Technology, “Explainer: Hydrogen” (May 23, 2024), https://climate.mit.edu/explainers/hydrogen.
[56] U.S. DOE, “Overview of Hydrogen Internal Combustion Engine (H2ICE) Technologies” (accessed on May 22, 2025), Hydrogen and Fuel Cell Technologies Office, https://www.energy.gov/sites/default/files/2023-03/h2iqhour-02222023.pdf.
[57] Hussein Basma et al., “Total Cost of Ownership of Alternative Powertrain Technologies for Class 8 Long-Haul Trucks in the United States” (2023), https://theicct.org/wp-content/uploads/2023/04/tco-alt-powertrain-long-haul-trucks-us-apr23.pdf.
[58] Alessandro Magnino et al., “Total Cost of Ownership Analysis for Hydrogen and Battery Powertrains: A Comparative Study in Finnish Heavy-Duty Transport” (September 2, 2024), Journal of Energy Storage Part A Vol. 99. , https://doi.org/10.1016/j.est.2024.113215.
[59] Jeffery Short, Alexandra Shirk, and Alexa Pupillo, Charging Infrastructure Challenges for the U.S. Electric Vehicle Fleet (December 2022), ATRI, https://truckingresearch.org/2022/12/new-atri-research-evaluates-charging-infrastructure-challenges-for-the-u-s-electric-vehicle-fleet/.
[60] California Hybrid and Zero-Emission Truck and Bus Voucher Incentive Project (HVIP), Tractor Category: Discover Full Specs, (May 2025), https://californiahvip.org/vehicle-category/heavy-duty/.
[61] Xi Cheng and Jane Lin, “Is Electric Truck a Viable Alternative to Diesel Truck in Long-Haul Operation?” (April 2024), Transportation Research Part D: Transport and Environment 129, https://doi.org/10.1016/j.trd.2024.104119.
[62] U.S. EPA, “SmartWay Heavy-Duty Truck Electrification Resources” (accessed on May 22, 2025), https://www.epa.gov/smartway/smartway-heavy-duty-truck-electrification-resources.
[63] Calstart, “Zero-Emission Technology Inventory” (accessed on May 22, 2025), https://globaldrivetozero.org/tools/zero-emission-technology-inventory/.
[64] Chad Hunter et al., “Spatial and Temporal Analysis of the Total Cost of Ownership for Class 8 Tractors and Class 4 Parcel Delivery Trucks” (2021), National Renewable Energy Laboratory NREL/TP-5400-71796, https://docs.nrel.gov/docs/fy21osti/71796.pdf.
[65] Nathan Bomey, “Why the next truck you see may be a quiet, zero-emission hydrogen fuel cell rig” (October 26, 2020), USA Today, https://www.usatoday.com/story/money/2020/10/26/hydrogen-trucks-nikola-gm-toyota-hyundai-zero-emissions/5981340002/.
[66] Adeel Ahmed et al., “Hydrogen fuel and transport system: A sustainable and environmental future” (November 16, 2015), International journal of hydrogen energy 41.3: 1369-1380, https://doi.org/10.1016/j.ijhydene.2015.11.084.
[67] Global Market Insights, “North American Hydrogen Trucks Market Size” (February 2025), https://www.gminsights.com/industry-analysis/north-america-hydrogen-trucks-market.
[68] Michael Wayland, “By ‘land, sea and air,’ GM plans to expand fuel-cell business beyond EVs” (June 21, 2021), CNBC, https://www.cnbc.com/2021/06/21/by-land-sea-and-air-gm-to-expand-fuel-cell-business-beyond-evs.html.
[69] Transport Topics, “Manufacturers Strive to Strengthen Hydrogen Fuel Cell Tech” (May 2, 2025), https://www.ttnews.com/articles/oems-hydrogen-fuel-cells; U.S. DOE, “Hydrogen-Powered Heavy-Duty Truck Establishes New Threshold by Traveling 1,800 Miles on a Single Fill” (December 17, 2024), https://www.energy.gov/eere/fuelcells/articles/hydrogen-powered-heavy-duty-truck-establishes-new-threshold-traveling-0.
[70] Massachusetts Institute of Technology, “Explainer: Hydrogen” (May 23, 2024), https://climate.mit.edu/explainers/hydrogen.
[71] California Air Resources Board, “Fiscal Year 2014-15 Funding Plan for the Air Quality Improvement Program and Low Carbon Transportation Greenhouse Gas Reduction Fund Investment” (May 23, 2014), www.californiahvip.org.
[72] FedEx Newsroom, “FedEx Long-Term Commitment to Sustainability Gets a Boost: Emission Reduction Goal Increased Fifty Percent” (2012), https://newsroom.fedex.com/newsroom/fedex-long-term-commitment-to-sustainability-gets-a-boost-emissions-reduction-goal-increased-fifty-percent/.
[73] UPS, “Electrifying Our Future” (July 2022), https://about.ups.com/us/en/our-impact/sustainability/sustainable-services/electric-vehicles—about-ups.html.
[74] Ibid.
[75] Alex Leslie and Dan Murray, An Analysis of the Operational Costs of Trucking: 2024 Update (June 2024), ATRI, https://truckingresearch.org/2024/06/new-atri-research-industry-costs-increased-more-than-6-percent-during-freight-recession/.
[76] U.S. DOE, “National Average Retail Fuel Prices on an Energy-Equivalent Basis, January 2025” (January 2025), https://afdc.energy.gov/fuels/prices.html.
[77] Alyssa Sporrer, “5 Trucking Sustainability Trends for 2021” (November 13, 2020), Freight Waves, https://www.freightwaves.com/news/5-trucking-sustainability-trends-for-2021.
[78] American Council for an Energy Efficient Economy, “Maximizing Truck Load Factor” (November 2021), https://www.aceee.org/sites/default/files/pdfs/Load%20Factor%20Smart%20Freight%2011-18-21.pdf.
[79] Philippe Barla et al., “Information Technology and Efficiency in Trucking” (February 1, 2010), Centre for Data and Analysis in Transportation, https://www.jstor.org/stable/40389563.
[80] Schiller, R. “C-TIP Evaluation: Results and Lessons Learned” (January 1, 2012), Talking Freight Presentation.
[81] Ibid.
[82] Walmart “Global Responsibility Report” (2012) , http://cdn.corporate.walmart.com/db/e1/b551a9db42fd99ea24141f76065f/2014-global-responsibility-report.pdf.
[83] Ibid.
[84] Ibid.
[85] Santalucia, A. et al. “Beyond SmartWay: New Opportunities for Fuel Savings and Emission Reductions in the Trucking Sector” (2011), ICF International.
[86] FHWA, “Compilation of Existing State Truck Size and Weight Limit Laws” (May 2015), https://ops.fhwa.dot.gov/freight/policy/rpt_congress/truck_sw_laws/index.htm.
[87] The Federal government began regulating truck size and weight limits in 1956 with the construction of the Interstate Highway System. Congress established a maximum gross vehicle weight limit of 73,280 pounds along with maximum weights of 18,000 pounds on single axles and 32,000 pounds on tandem axles for vehicles operating on the Interstate system. The Federal-Aid Highway Act Amendments of 1974 increased the maximum GVW to 80,000 pounds and to 20,000 pounds on single axles and 34,000 pounds on tandem axles. This increase was due in part to the rising fuel costs at the time. The Surface Transportation Assistance Act of 1982 expanded the federal authority, essentially overriding several more restrictive “barrier” states located along the Mississippi that had not adopted the previous size and weight limit increase. The most recent legislation related to truck size and weight limits was in the Intermodal Surface Transportation Efficiency Act of 1991, which froze the limits to those established in 1974.
[88] Bureau of Transportation Statistics and Federal Highway Administration, “Permitted Longer Combination Vehicles on the National Highway System: 2017” (accessed on May 28, 2025), https://www.bts.gov/permitted-longer-combination-vehicles-national-highway-system-2017.
[89] Heavy Duty Trucking, “Bill Would Make Larger Truck Pilot Program Permanent” (January 25, 2011), https://www.truckinginfo.com/105763/bill-would-make-larger-truck-pilot-program-permanent.
[90] H.R 2112 was signed into law on November 18, 2011 and contained the following:
“Sec. 125. Section 127(a)(11) of title 23, United States Code, is amended to read as follows:
(11)(A) With respect to all portions of the Interstate Highway System in the State of Maine, laws (including regulations) of that State concerning vehicle weight limitations applicable to other State highways shall be applicable in lieu of the requirements under this subsection through December 31, 2031. (B) With respect to all portions of the Interstate Highway System in the State of Vermont, laws (including regulations) of that State concerning vehicle weight limitations applicable to other State highways shall be applicable in lieu of the requirements under this subsection through December 31, 2031.
[91] Mike Tunnell, Energy and Emissions Impacts of Operating Higher Productivity Vehicles, Update 2008 (2008), ATRI, https://truckingresearch.org/2008/03/26/energy-and-emissions-impacts-of-operating-higher-productivity-vehicles/.
[93] Ontario Ministry of Transportation, “Long Combination Vehicle (LCV) Program” (accessed on May 28, 2025),, http://www.mto.gov.on.ca/english/trucks/long-combination-vehicles.shtml.
[93] Canadian Trucking Alliance, “Evaluating Reductions in Greenhouse Gas Emissions Through the Use of Turnpike Double Truck Combinations and Defining Best Practices for Energy Efficiency” (2006).
[94] John Woodrooffe and Lloyd Ash, “Economic Efficiency of Long Combination Transport Vehicles in Alberta” (2001), http://www.transportation.alberta.ca/Content/docType61/production/LCVEconomicEfficiencyReport.pdf.
[95] Compared to traffic levels if those vehicle movements had occurred in non-HPV trucks.
[96] Ibid.
[97] TCA, “High Productivity Freight Vehicle Monitoring” (accessed on May 28, 2025), https://tca.gov.au/scheme/high-productivity-freight-vehicle-monitoring/.
[98] TCA, “Smart OBM Systems are here” (accessed on May 22, 2025), https://tca.gov.au/smart-obm-systems/.
[99] U.S. DOT, “Comprehensive Truck Size and Weight Study” (2000), https://www.nrc.gov/docs/ml1208/ml120810039.pdf.
[100] FMCSA, “MAP21 Moving Ahead for Progress in the 21st Century Act” (December 10, 2024) , https://www.fmcsa.dot.gov/mission/policy/map-21-moving-ahead-progress-21st-century-act.
[101] Avery Vise, “FedEx presses Congress for 33-ft. twin trailers” (February 27, 2014), Fleet Owner Magazine, http://fleetowner.com/fleet-management/fedex-presses-congress-33-ft-twin-trailers.
