Office of Operations Freight Management and Operations

Freight and Air Quality Handbook

3.0 Strategies for Freight Transportation-Related Emission Reduction/Air Quality Improvement Projects

There are many strategies available to state and local transportation planners and air quality practitioners to reduce emissions from the freight sector. These range from technology applications to operational, policy, and regulatory initiatives. This section describes the different strategies and explains how they work. It also outlines their emissions benefits, cost considerations, possible interactions with other strategies, and co-benefits that may result (such as decreased noise). These strategies can be implemented as standalone projects to improve air quality, or they can be incorporated into transportation projects as environmental mitigation measures. The strategies are divided into two categories:

  • Technology strategies, which include engine treatments, repowering, alternative fuels, and energy efficiency improvements; and
  • Operational and transportation system management strategies, which include anti-idling strategies, congestion management techniques, and operational changes that freight generators and private businesses can employ to reduce emissions.

These strategies fall into a wide range of cost, benefit, and timeframe considerations.

3.1 Technology Strategies

Technology strategies to reduce freight emissions take many forms, including retrofitting existing engines with more modern emission control equipment, replacing older engines with cleaner running ones, the use of alternative fuels, and the use of more energy-efficient engines and equipment. Table 3.1 summarizes the most common technology applications for reducing diesel emissions. Several typical applications of each broad strategy type are outlined, along with key issues and considerations for each. Readers who require more information about a particular strategy or family of strategies can consult the detailed descriptions that follow.

Table 3.1 Summary of Technology Strategies to Reduce Freight Emissions

Summary of Technology Strategies to Reduce Freight Emissions
Strategy Type Purpose Typical Applications Key Issues
Exhaust Aftertreatments Remove pollutants from the exhaust stream
  • Diesel Particulate Filters (removes PM, CO, and sometimes NOx)
  • Require ULSD, so applications primarily limited to on-road trucks
  • Exhaust gases must be held at specified temps for some applications (passive)
Exhaust Aftertreatments Remove pollutants from the exhaust stream
  • Diesel Oxidation Catalysts (removes PM and CO)
  • Do not require ULSD, making it cost-effective treatment for off-road equipment
  • Overall emissions reduction limited, compared to other strategies
Exhaust Aftertreatments Remove pollutants from the exhaust stream
  • Flow-Through Filters (removes PM, CO)
  • Not as effective as DPFs
  • Can be used by any fuel type, making it useful for older trucks and off-road equipment (including locomotives, marine vessels)
Exhaust Aftertreatments Remove pollutants from the exhaust stream
  • Selective Catalytic Reduction (removes NOx)
  • Require tuning, making them better suited for engines with predictable duty cycles (e.g., marine vessels)
  • Not well-suited for trucks due to varying engine loads
Repowering Replace older engines with cleaner burning equipment
  • New engine/pre-2007 engine (reduces all pollutants)
  • New engines have latest emissions control technology
  • Pre-2007 engines are superior to most older engines, but not as advanced as brand new ones
Repowering Replace older engines with cleaner burning equipment
  • New vehicle replacement (reduces all pollutants)
  • Can be more cost-effective to replace old vehicles altogether
  • Sponsors must ensure old engines are scrapped and do not reenter service
Alternative Fuels Adopt cleaner-burning fuels
  • Liquefied petroleum gas (reduces NOx, PM, GHG)
  • Inappropriate for marine and rail applications due to low-energy content
  • Fuel distribution network already exists
Alternative Fuels Adopt cleaner-burning fuels
  • Natural gas (reduces PM)
  • Requires special fueling facilities
  • Similar performance to diesel
Alternative Fuels Adopt cleaner-burning fuels
  • Biodiesel (reduces PM, CO)
  • 20 percent biodiesel blend can be used without engine modifications
  • May slightly increase NOx emissions
Alternative Fuels Adopt cleaner-burning fuels
  • Fuel-borne catalyst (reduces PM)
  • EPA cautious about their use as may increase emissions of some particles
Alternative Fuels Adopt cleaner-burning fuels
  • Low-sulfur diesel (reduces PM), emulsified diesel (reduces PM, NOx)
  • No engine modifications required, but more expensive fuel
  • Emulsified fuel contains less energy per gallon than conventional diesel
Alternative Fuels Adopt cleaner-burning fuels
  • Fuel cells
  • Not practical at this time
Energy Efficiency Save fuel/reduce emissions through superior design
  • Hybrid-electric vehicles
  • Available for medium-duty tractor trailers
  • Most suited for trucks operating primarily in urban areas
Energy Efficiency Save fuel/reduce emissions through superior design
  • Weight-saving modifications (reduce all pollutants)
  • Often low-cost
    Enhances productivity by increasing payload capacity
Energy Efficiency Save fuel/reduce emissions through superior design
  • Improved aerodynamics, reduced rolling resistance (reduce all pollutants)
  • Fuel savings may offset capital outlay, making this a cost-neutral strategy
Energy Efficiency Save fuel/reduce emissions through superior design
  • Marine vessel efficiency improvements
  • Generally not controlled by ports
Energy Efficiency Save fuel/reduce emissions through superior design
  • 'Green' locomotives (reduce all pollutants)
  • Genset or similar rail equipment can be expensive
  • These investments be combined with larger capital improvements

3.1.1 Aftertreatment ("Tailpipe")/Engine Controls

This category includes emission control devices that can be integrated into both new engines and retrofits. This handbook will focus on retrofits, since new engine standards are largely addressed by Federal regulations for engine manufacturers. There are several types of retrofits available for freight diesel engines:

  • Diesel Particulate Filters (DPF) – These devices remove particulate matter from diesel exhaust. DPFs used in freight vehicle applications typically dispose of accumulated particles by burning them off in a process known as "filter regeneration." Sulfur in diesel fuel can interfere with filter regeneration, which is why the use of ULSD is necessary to achieve maximum emission reductions with this technology. In combination, a DPF installed on an engine using ULSD can reduce PM and CO emissions by 60 to 90 percent (http://www.epa.gov/oms/schoolbus/retrofit.htm). Figure 3.1 shows how the technology works. Diesel exhaust enters the flow channels in the filter (Step 1), but is blocked by walls at the end of the channels (Step 2). This forces the exhaust gases to move through the porous walls of the filter. Particulate matter is captured on the walls and burned off during filter regeneration. DPFs are best suited to truck applications because they require low-sulfur fuel. However, they have been successfully used in locomotives (the BNSF and UP railroads have both retrofitted some of their locomotives with DPFs). The high sulfur content of bunker fuel makes DPF technology impractical for marine cargo applications.

    Diesel particulate filters are divided into two categories, depending on how filter regeneration is accomplished:

    • Passive DPF uses a catalytic material which enables trapped particulate matter to be burned off at a lower temperature. Exhaust gases must be at a specified temperature for a certain period of time in order for this technology to work; otherwise, the filter will become plugged with soot, interfering with filtration and eventually causing engine damage. It is therefore important to verify the duty cycle and operating characteristics of equipment proposed for retrofits with this technology.
    • Active DPF systems do not use exhaust gas heat to burn off trapped PM. Instead, they regenerate by passing electrical current through the filter, adding fuel to achieve the necessary combustion temperature, or adding a catalyst that reacts with the PM. Active DPF can be used in engines with lower exhaust gas temperatures.
  • DPF with NOx Catalyst – Some DPF technologies have been coupled with NOx catalysts to control NOx emissions. A NOx catalyst is installed downstream from the DPF; since the particulate matter already is removed from the exhaust gases, the catalyst can work without getting clogged up by the soot.
  • Diesel Oxidation Catalyst (DOC) – Diesel oxidation catalysts use a chemical process to break down the pollutants found in diesel exhaust, converting them into less harmful compounds. These devices can reduce PM emissions by 20 percent and CO pollutants by up to 40 percent. Unlike DPFs, DOCs do not require the use of low-sulfur fuel. DOC technology only works on the soluble organic fraction of diesel particulate matter emissions, which is why the overall emissions reduction is limited. DOCs are suitable for truck and rail applications as well as some marine applications, but the technology is not yet fully developed for the largest marine engines.
  • Flow-Through Filter (FTF) – Flow-through filters work by forcing exhaust gases to flow through a filter material (such as wire mesh) that introduces turbulence to the exhaust flow. This medium is treated with a catalyst that reduces emissions of PM and CO. Because the exhaust is interrupted as it passes through the filter, it spends more time in contact with the catalyst, thereby reducing emissions. FTFs are not as effective as DPFs at removing pollutants, but they also are less likely to become clogged up and can be used with any type of diesel fuel. This makes them ideal for engines or operating environments that may be unsuitable for DPF applications, such as trucks using off-road diesel fuel (e.g., logging trucks), locomotives, and cargo ships.
  • Selective Catalytic Reduction (SCR) – SCR is a technology for controlling NOx emissions that uses a catalyst to convert NOx to nitrogen and water. Installed downstream of a DPF, the SCR system injects diesel exhaust fluid (Diesel exhaust fluid is a solution of water and urea (an organic compound also known as carbamide)) into the hot exhaust gases, which then travel through a catalyst where they are converted to nitrogen and water and emitted through the tailpipe. Although these systems are most frequently found in industrial applications such as utility boilers, they have successfully been applied to marine diesel engines, locomotives, and even automobiles. The chief obstacle to adopting this technology for a wider range of vehicles is the need to tune the SCR system to the operating cycle of the engine. Engines with predictable duty cycles (such as large cargo ships) are well suited to SCR retrofits (There have been successful demonstrations of stationary SCR systems at rail yards that capture exhaust gases with a fume hood positioned above the railroad tracks and transfer it to an emissions treatment system). Trucks' operating cycles vary widely depending on many factors like driver habits, stop-and-go traffic, and hilly terrain, making it harder to use SCR systems.

Figure 3.1 Diesel Particulate Filter

Diagram of a diesel particulate filter showing how exhaust gases flow through it.

3.1.2 Repowering

Repowering refers to replacing an old engine with a newer, cleaner engine or converting to electric power (as in certain types of cargo-handling equipment, such as port gantries). Government agencies often offer tax credits or other incentives to encourage businesses to repower equipment. In general, there are four options for repowering:

  • New Engine – The old engine is replaced with a brand new one that meets all of the latest emissions control regulations;
  • Older (pre-2007) Engine – The old engine is replaced with an engine manufactured before 2007 and retrofitted with an emissions control device such as those discussed above;
  • Alternate Fuel/Electricity – This option involves converting the equipment to run off electricity or an alternate fuel, such as propane. This is a common practice for cargo-handling equipment such as cranes and forklifts; and
  • New Vehicle Replacement – In some cases, it can be more economical to simply replace a piece of equipment with an entirely new model that employs the latest emissions control technology. In those instances, agencies can offer incentives to get businesses to replace older equipment, thereby removing more polluting vehicles from service.

No matter which strategy is employed, it is important to ensure that the old equipment is scrapped rather than sold and put back into service. This will ensure that the emissions benefit is fully realized.

3.1.3 Alternative Fuels

There are several alternative fuel technologies available that provide cleaner-burning options for freight vehicles and equipment. The focus here is on common alternative fuels using proven technologies that already are available; potential advanced technologies that are not yet practical (such as fuel cells) are discussed briefly to make readers aware of their current status.

  • Natural Gas – Compressed natural gas (CNG) is a mixture of hydrocarbons (primarily methane, a greenhouse gas) extracted from gas wells or produced in conjunction with crude oil. Vehicles powered by CNG perform similarly to those powered by diesel fuel, but CNG vehicles emit 70 to 90 percent less particulate matter than conventional diesels, since burning natural gas produces virtually no particulate matter. CNG may offer limited GHG reduction benefits, although one study of heavy-duty applications found that on a life-cycle basis GHG emissions were approximately equal to those from diesel fuel (Clark, W., 2007: "Market Penetration Issues for Biodiesel." National Renewable Energy Laboratory, http://www.sae.org/events/sfl/presentations/2007clark.pdf). CNG fleets require special refueling and maintenance facilities due to the specific requirements for handling and storing CNG. CNG fueling infrastructure can be found all over the country, but is somewhat sparse in some Rocky Mountain states, the Great Plains, and the South (see Figure 3.2). California and certain parts of New England have the most CNG stations. CNG has an added advantage in that the majority of it is produced in the United States, reducing the nation's dependence on foreign oil. CNG-powered equipment costs significantly more than equivalent diesel-powered vehicles. The San Pedro Bay Ports in Southern California are now running a demonstration project with CNG-powered trucks that transport containers from ships to consolidation yards in the area. The project is part of the San Pedro Bay Ports Clean Air Action Plan, which is detailed in Section 5.1.3. A variation is liquefied natural gas (LNG), which is a better choice for rail applications because of its greater density, which reduces the frequency of refueling.

Figure 3.2 Natural Gas Fueling Stations by State (2009)

Map of the United States showing the number of natural gas refueling stations in each state.

Source: U.S. Department of Energy Alternative Fuels and Advanced Vehicles Data Center.

  • Liquefied Petroleum Gas (LPG) – Commonly known as propane, LPG can be used to replace gasoline in light-duty vehicles and diesel in heavy-duty vehicles. Several original equipment manufacturer (OEM) LPG engines are available for heavy-duty vehicle use, including delivery trucks, school and shuttle buses, and recycling trucks. In addition, a well-developed distribution network of LPG fueling stations already exists. However, LPG has a lower energy content than traditional fossil fuels, making it inappropriate for marine and rail freight vehicles because of the increased refueling frequency.
  • Low-Sulfur Fuels for Marine Engines while in Proximity to Shore – As discussed in Section 2.2, most large ocean-going vessels utilize bunker fuel, which is inexpensive but has high levels of sulfur. In response, many coastal jurisdictions are now mandating the use of low-sulfur diesel fuel by cargo vessels when they are operating close to shore. California is a pioneer in this area; in July 2008, the State began requiring large vessels to use low-sulfur fuel whenever they are within 24 miles of the coast. The new rules require ships to burn fuel with 0.5 percent or less sulfur in coastal waters beginning in 2009; in 2012, they must use fuel with 0.1 percent or less sulfur content. By contrast, bunker fuel typically has a sulfur content of 3.5 percent. Complying with these rules requires that ships have the capability to be "dual-fueled"; that is, they must be designed or retrofitted with a separate fueling system allowing the use of distillate fuel in the auxiliary engines. Research has shown that many large vessels such as containerships already have separate fuel tanks for their auxiliary engines. These vessels have the potential for dual-fuel operations, but currently operate on residual fuel when on-shore due to its lower cost – fuel costs are a major component of ocean shipping. Vessel manufacturers have been responding by incorporating more low-sulfur tanks in new ships (Port of Los Angeles and Starcrest Consulting Group LLC, Evaluation of Low Sulfur Marine Fuel Availability, July 2005).
  • Emulsified Diesel Fuel – Emulsified diesel fuel is a mixture of diesel fuel with water and emulsifying additives. This reduces PM and NOx emissions, but emulsified fuel also contains less energy due to the addition of water, resulting in power losses and decreased fuel economy. The presence of water also can be problematic; if a vehicle sits unused for too long, the water will separate from the fuel, which can harm the engine. Emulsified diesel also costs about 20 cents more per gallon than regular diesel. EPA data show that the use of this fuel can reduce PM emissions by 20 to 50 percent and NOx by 5 to 30 percent (United States Environmental Protection Agency, Office of Transportation and Air Quality, Clean Fuel Options for Heavy-Duty Trucks and Buses, June 2003).
  • Ultra-Low Sulfur Diesel Fuel – As mentioned in Section 2.2, the EPA has mandated the use of ULSD in new on-road trucks since the 2007 model year, and this fuel has been available at retail stations since mid-2006. ULSD (defined as diesel fuel with 15 parts per million or less sulfur content) enables the use of more advanced emissions control technologies such as the diesel particulate filters described above. Locomotives, marine engines, and off-road trucks are not required to use ULSD at this time, so there is an opportunity to further reduce emissions by adopting low-sulfur diesel fuel in these other modes (See, for example, the new California regulations requiring low sulfur fuels for oceangoing vessels operating near the coastline discussed in Section 2.3.2).
  • Biofuels – This is a broad category of alternative fuels that includes gasoline substitutes such as corn or cellulosic ethanol. The most relevant for freight transport is biodiesel, which is a renewable fuel that can be produced from vegetable oils and animal fats. Biodiesel is safe and biodegradable. It can reduce PM, CO, and hydrocarbon (HC) emissions, but may also slightly increase NOx emissions. A blend of 20 percent biodiesel and 80 percent conventional diesel (known as B20) can be used in diesel engines without requiring modification. This blend reduces PM emissions by about 10 percent, but increases NOx emissions by two percent. Pure biodiesel (B100) reduces PM emissions by about 40 percent, but often requires engine modifications to work and is typically not suitable for cold climates (Ibid).
  • Fuel-Borne Catalysts (FBC) – Also known as fuel additives, FBCs are metallic chemicals added to diesel fuel to improve combustion and thereby reduce PM emissions. These additives can reduce oxidation temperatures for PM, so that a DPF would not have to reach as high a temperature to enable soot in the exhaust to be burned off. However, it should be noted that these additives, when used in dosages above a certain level, can increase emissions of very fine metal oxide particles. For this reason, the EPA has been cautious about the use of FBCs. To minimize the amount of metals discharged into the atmosphere while maximizing emissions reductions, FBCs can be combined with retrofits such as a DPF (Environmental Defense, "Cleaner Diesel Handbook: Bring Cleaner Fuel and Diesel Retrofits into Your Neighborhood," April 2005).
  • Fuel Cells – Fuel cells are an emerging technology that may have useful applications for transportation in the future. Unlike hybrid-electric vehicles, which store energy from an external source in an on-board battery, fuel cell vehicles (FCV) create their own electricity. This is accomplished through a chemical reaction using hydrogen fuel and oxygen from the air. The hydrogen can be supplied either as pure hydrogen stored in a tank or from hydrogen-rich fuels such as methanol, natural gas, or even gasoline. The latter technique requires a "reformer" to extract pure hydrogen from the fuel for use in the fuel cell; this process emits some carbon dioxide, but not nearly as much as a conventional engine. Vehicles fueled by pure hydrogen emit no pollutants; the only byproducts of power generation are water and heat. There are a number of obstacles to the widespread adoption of this technology for the transport sector, including cost, distribution, and storage of hydrogen fuel, and competition with other technologies such as hybrids. Although limited quantities of FCVs, such as the Honda FCX Clarity, are available to the public, they will not be mass-produced for a number of years, and freight fuel-cell vehicles may take longer to be commercialized.

3.1.4 Energy Efficiency

More efficient engines and equipment generally reduce emissions of all pollutants, including GHG. This includes a variety of options such as hybrid-electric vehicles, improved vehicle aerodynamics, more efficient tires, and reduced vehicle weight. Energy efficiency strategies have the advantage of reducing fuel costs, sometimes making them cost-neutral. EPA's SmartWay transportation program (discussed in more detail in Section 4.4), which packages a suite of efficiency improvements specifically for truckers, is premised on the notion that the package pays for itself. Most of the truck upgrades identified below qualify for special low-interest financing through the SmartWay transportation program.

  • Hybrid-Electric Vehicles – Hybrid-electric technology, already becoming widespread in passenger vehicles, is now available for medium-duty tractor-trailers. There are now diesel hybrid-electric tractors available targeted towards general freight haulers and food/beverage distributors. These tractors use an electric motor with an automated transmission/clutch combined with a traditional internal combustion diesel engine and transmission, and utilize regenerative braking to recapture power otherwise lost during deceleration and braking (Regenerative braking captures the kinetic energy of the vehicle (which would otherwise be wasted as heat through conventional braking) and stores it in the vehicle's battery to provide motive power. It is distinct from the dynamic braking used by trains). Regenerative braking is more effective in large commercial vehicles because their greater mass requires more power to stop, meaning there is more potential energy to capture and reuse. This technology can cut fuel consumption by 25 to 50 percent depending on the application. Although hybrid-electric vehicles can cost up to $40,000 more than regular trucks, a Federal tax credit, the Alternative Motor Vehicle Credit, is available to offset this cost. It contains provisions for Qualifying Heavy Hybrid vehicles, which are defined as new vehicles with a gross vehicle weight over 8,500 pounds that meet the definition of a qualifying hybrid vehicle; the Internal Revenue Service maintains a list of such vehicles (http://www.irs.gov/businesses/article/0,,id=175456,00.html). Hybrid vehicles are most effective in stop-and-go traffic, suggesting that hybrid vehicles are best suited for urban applications such as delivery trucks. Figure 3.3 shows how a typical hybrid-electric truck system works. The electric motor supplies additional power from a battery pack to supplement the diesel engine and while recharging the batteries through regenerative braking.

Figure 3.3 Typical Hybrid-Electric Propulsion System

Diagram of a hybrid-electric engine showing its layout.

Source: Electric Transit Vehicle Institute.

  • Improved Vehicle Aerodynamics – At highway speeds, wind resistance (aerodynamic drag) accounts for the preponderance of truck energy losses. Similarly, line-haul freight trains lose a significant amount of energy to drag because of their aerodynamically unfavorable profile, unshielded space between cars, and lack of covers on empty cars. Improving vehicle aerodynamics is another way to cut fuel consumption and emissions. Aftermarket fairings attached to the front and/or belly of truck trailers can improve fuel efficiency by up to six percent (Figure 3.4). There also are modifications to the tractor that can improve fuel economy, such as upgraded front bumpers, air dams, and side mirrors. Roof fairings, cab extenders, and side fairings installed on a tractor can achieve fuel savings of up to 600 gallons per year and emissions reductions of over five metric tons of GHG. For instance, in Figure 3.5 the air dam visible above the truck cab improves air flow and increases fuel efficiency. Similarly, covering empty rail cars, modifying how intermodal cars are loaded, and minimizing open areas between cars can help improve train aerodynamics. It also is relatively inexpensive to implement these strategies, either by ordering them as options on new trucks or rail cars or by retrofitting older equipment, so the costs are recouped quickly through improved fuel efficiency (U.S. Environmental Protection Agency SmartWay Transport Partnership, "A Glance at Clean Freight Strategies: Improved Aerodynamics," February 2004).

Figure 3.4 Example of Freight Vehicle Aerodynamic Improvements

Picture of a truck showing side fairings underneath the trailer and an air dam above the cab.

Source: Environmental Protection Agency.

  • More Efficient Tires – Tire rolling resistance accounts for about 13 percent of truck energy use. Many truck fleets have begun to switch to more fuel-efficient single wide tires, which replace the traditional dually style tires found on most tractor-trailers. These tires improve fuel efficiency by reducing weight and rolling resistance (although impacts to infrastructure are not yet quantified). The EPA has found that the use of single wide-base tires can improve fuel economy by two to five percent over conventional dual tire setups. On a combination long-haul truck, this equates to a fuel savings of up to 400 gallons per year, and a reduction in CO emissions of four metric tons annually (U.S. Environmental Protection Agency SmartWay Transport Partnership, "A Glance at Clean Freight Strategies: Single Wide-Based Tires," February 2004). In addition, wheels for these tires cost less than dual wheels, while the tires themselves are cost-competitive with equivalent dual tires. This makes single wide tires an attractive option for new trucks.
  • Reduced Wheel-to-Rail Friction – Railroads periodically apply grease to their tracks to reduce fuel consumption and protect infrastructure from excessive wear. Conventional lubrication systems apply large and uneven amounts of lubricant to the rail, resulting in wasted material and poor transfer of grease to the passing train wheels. Newly developed computer controlled systems provide a better application of lubricant and limit the amount of grease applied to reduce excessive applications that lengthen required braking distances. Wheel and rail wear is reduced as well as fuel consumption.
  • Weight Reduction – Reducing the weight of a freight vehicle directly affects the energy required to move it and, therefore, has an impact on emissions. Owners can install weight-saving devices on truck tractors such as aluminum alloy wheels and aluminum axle hubs that replace heavier steel components. There are even greater opportunities to save weight in the trailer, where aluminum parts can be used in the roof and upright posts as well as floor joists. Overall, these modifications can reduce the empty truck weight (known as "tare weight") by up to 3,000 pounds, saving between 200 and 500 gallons of fuel annually and reducing greenhouse gas emissions by two to five metric tons per year. These weight restrictions also allow increased payload which may result in no change in gross vehicle weight and fuel savings per mile, but may reduce the miles travel and increase productivity of the vehicle. Aluminum rail cars already are available and in use, and are up to one-third lighter than comparable steel cars. Aluminum also offers exceptional resistance to corrosion from certain cargoes (like high-sulfur coal) and is more valuable for recycling purposes when the rail car is scrapped. Modifications that reduce weight have the added benefit of allowing the vehicle to carry a larger payload, thereby improving productivity. Lighter-weight trucks and trailers do command a price premium since the lightweight components are more expensive, making them more common in weight-sensitive applications like heavy goods and refrigerated foods (U.S. Environmental Protection Agency SmartWay Transport Partnership, "A Glance at Clean Freight Strategies: Weight Reduction," February 2004). The higher carrying capacity of aluminum rail cars may recoup their greater initial cost within two years.
  • Marine Vessel Efficiency Improvements – There also are a number of improvements that can be made to cargo ships to make them more fuel efficient. Although port planners and other officials typically have little control over things like ship design, some of the available technologies are summarized here for readers wishing to explore these options:
    • Energy-efficient paint for vessel hulls. Ship owners must regularly paint their hulls to avoid fouling by barnacles and other marine life. There are a variety of hull paints that reduce drag and fuel consumption. The Emma Maersk, one of the largest containerships in the world, uses a silicone-based hull paint that improves efficiency by creating a very slick surface that reduces drag and helps to prevent fouling. It should be noted that many marine paints contain toxicants that are released over time, especially during underwater hull cleaning, thereby contributing to water pollution problems. However, there are paint choices (such as the silicone paint) that contain no biocides.
    • Exhaust heat recovery systems. Another technology application available for cargo ships is exhaust heat recovery. These systems pass hot exhaust gases through a steam generator, which powers electrical generators to generate electricity for shipboard use. On the Emma Maersk, such a system produces electrical power equivalent to about 12 percent of engine output while also using the steam to provide heat.
    • Improved hull design. Certain hull designs offer better hydrodynamics than others. For example, reducing vessel displacement by increasing the hull width by only 0.25 meters allows for a reduction of 3,000 tons of ballast, reducing propulsion energy requirements by 8.5 percent (Wartsila, 2009). Use of interceptor or trim planes (vertical plates fitted to the ship’s transom) can improve fuel consumption by 1 to 4 percent, or up to 10 percent if the interceptor or trim plane is used in conjunction with a ducktail (an extension of the rear of the ship that reduces water resistance).
  • Enhanced Locomotive Engine Technologies – There are a number of technologies either existing or under development that promote better fuel efficiency in railroad locomotives, including:
    • Common rail fuel injection systems allow for a more controlled fuel injection rate across all engine speeds by storing fuel at high pressures along a common rail connected to each cylinder. This yields more efficient combustion while providing smoother, quieter running engines, reducing GHG emissions and fuel consumption by at least 10 percent (International Union of Railways, 2002). The largest locomotive with a fuel injection engine currently available has a maximum horsepower of 4,000, appropriate for use in yard and line-haul operations.
    • Genset yard locomotives use multiple smaller (approximately 700 horsepower) diesel engines to provide only the power that is needed and have electronic engine controls to better match locomotive activities to operating conditions. Older locomotives can be retrofitted with genset engines, which are newer and more efficient than larger conventional yard engines, and are certified to EPA Tier III emission standards. This technology can save between 15 and 24 gallons of diesel fuel per locomotive, per day, with accompanying emissions reductions.
    • Hybrid propulsion systems employ a small, efficient diesel engine to charge a set of batteries which provides power to the locomotive, similar to a hybrid system on a passenger car or truck. The engine operates only when the batteries need to be recharged. As a result, the diesel engine can stay within its optimal load range, reducing emissions and fuel consumption. These systems are most effective for switch locomotives in stop-and-go railyard operations, although line-haul versions also have been developed.

The chief limitations of these approaches are their very high capital cost and slow introduction due to the long life cycle of the rail fleet. Some states (like California and Texas) have adopted programs to subsidize the implementation of these technologies. Such programs can help accelerate the adoption of these strategies, providing public benefits before the railroads would do so on their own.

3.2 Operational Strategies and Transportation System Management

There are a variety of operational and system management strategies that policy-makers can employ to reduce freight vehicle emissions. These usually take the form of local regulations and ordinances (such as anti-idling programs), congestion mitigation efforts geared towards speeding the flow of freight (such as improved port access), or operational changes to reduce emissions (such as speed reduction). Table 3.2 summarizes some of the most common approaches and the potential issues, advantages, and co-benefits of each.

Table 3.2 Summary of Operational and Transportation System Management Strategies

Summary of Operational and Transportation System Management Strategies

Strategy Type

Purpose

Typical Applications

Key Issues

Anti-idling

Reduce/eliminate unnecessary idling
  • Truck stop electrification, auxiliary power units (reduces all pollutants)
  • Difficult to electrify all potential truck parking locations (rest areas, parking lots)
  • Auxiliary power units are significant initial cost to truck owner
  • Fuel savings offset costs
Anti-idling

Reduce/eliminate unnecessary idling

  • Anti-idling regulations (reduces all pollutants)
  • May be difficult to enforce
    Can be written specifically for freight vehicles
Anti-idling

Reduce/eliminate unnecessary idling

  • Locomotive idling limit device
  • Most effective in warm climates
Anti-idling

Reduce/eliminate unnecessary idling

  • Shore power (reduces all pollutants)
  • Requires large capital outlay (vessel retrofits and land-side hookups)
  • Currently no universal standard

Congestion Mitigation

Relieve bottlenecks with capacity improvements or better system management
  • Port access improvements, truck-only lanes (reduces all pollutants)
  • Capacity expansion is typically expensive and has other environmental impacts
  • Few examples of truck-only lanes in the U.S.
Congestion Mitigation

Relieve bottlenecks with capacity improvements or better system management

  • Signal coordination (reduces all pollutants)
  • Low cost, but limited benefits
  • Some signal systems can detect trucks in traffic mix and adjust timing accordingly
Congestion Mitigation

Relieve bottlenecks with capacity improvements or better system management

  • Rail infrastructure improvements, grade separation (reduces all pollutants)
  • High capital costs
  • Grade separation also improves safety
Congestion Mitigation

Relieve bottlenecks with capacity improvements or better system management

  • Short-sea shipping (reduces all pollutants)
  • Time considerations, terminal and drayage costs, and requirements to purchase comparatively expensive U.S. built vessels (Jones Act) make competition with land modes difficult

Operational Changes

Modify business practices to minimize emissions
  • Speed reduction programs, driver training (reduces all pollutants)
  • Voluntary programs may have limited effectiveness
  • Trucks can be ordered with speed limiting devices
  • Fuel and maintenance savings may offset productivity loss
Operational Changes

Modify business practices to minimize emissions

  • Reduced pickup/dropoff idling for trucks (reduces all pollutants)
  • Often implemented as improved port operational strategies
Operational Changes

Modify business practices to minimize emissions

  • Weigh station bypass (reduces all pollutants)
  • Can improve monitoring and compliance
Operational Changes

Modify business practices to minimize emissions

  • Reduced empty mileage, circuitous routing (reduces all pollutants)
  • Not all origin-destination pairs have "balanced loads," making backhauls difficult to identify
    More difficult to reduce empty rail backhauls
    Reducing circuitous rail routing requires rail capacity expansion

3.2.1 Anti-Idling

Anti-idling strategies refer to efforts to reduce emissions by cutting down on the time freight vehicles spend idling (sitting in one place with the engine running). These strategies exist for all modes, including trucks, locomotives, and marine cargo vessels, and can be implemented through regulations, technology applications, or a combination of the two. Several strategies are outlined below.

  • Shore Power ("Cold Ironing") – Cargo ships usually switch to their auxiliary engines to provide power for ship operations while they are in port. Although some auxiliary engines use cleaner distillate fuel than the main engines, they still contribute to localized air pollution around port complexes since the ships may be idling for days at a time. To combat this problem, many ports are constructing shore power (also known as cold ironing) systems that provide clean electrical power to cargo vessels while they are in port. The U.S. Navy has been using cold ironing for decades, not because it cuts emissions, but rather because it reduces equipment wear and tear and saves fuel (which are ancillary benefits of implementing a shore power strategy). California, in general and the Ports of Los Angeles and Long Beach in particular, are driving the development of this technology in the United States. Cold ironing is a key part of the San Pedro Bay Ports Clean Air Action Plan (described below in Section 5.1.3.) The plan calls for all major cargo terminals at the ports to be equipped with shore power by 2016. In addition, the California Air Resources Board (CARB) is requiring all container, passenger, and refrigerated cargo ships to shut off their auxiliary engines while in port. Containerships lend themselves well to cold ironing, since they rely on land side cranes to load and unload cargo, rather than shipboard equipment that must be powered from the ship. Although shore power is a promising way to reduce cargo vessel emissions, capital costs and lack of standards are limiting its widespread adoption.
    • Significant capital costs. Cold ironing requires a large up-front capital investment both for ships and landside hookups. Retrofitting a containership typically costs between $200,000 and $500,000. However, some vessels are now being constructed with built-in shore power capability. Ports also can offer incentives to shipping lines to encourage them to adopt the technology; the Port of Long Beach recently signed an agreement with Matson Shipping Company whereby the company will retrofit five of its ships with shore power systems in return for tax incentives and discounted tariffs.
    • No universal standard. At this time, there is no internationally accepted universal standard for shore power systems. So, a cargo ship that is equipped for cold ironing at one port may not be able to hook up to a system at another port.
  • Idling Limit Devices on Rail Locomotives – These devices automatically shut off a rail locomotive's engine if it sits idle for a certain period of time, usually 15 minutes. This prevents unnecessary emissions from locomotives that are not in use. As with shore power, the San Pedro Bay ports are leaders in this area. By the end of 2008, all switch/helper locomotives operated by the Pacific Harbor Line (which provides switching services to the ports) were required to be equipped with 15-minute idle limit devices, followed by Class I switchers (in 2011) and line-haul locomotives (in 2014) (Ports of Los Angeles and Long Beach, "San Pedro Bay Ports Clean Air Action Plan Source Specific Standards"). CARB has promulgated similar regulations for locomotives that operate primarily in the State of California. Governmental agencies sometimes offer grants or other assistance to encourage railroads to install these devices. For example, the Texas Commission on Environmental Quality (TCEQ) offers grants of up to $5,000 per ton of NOx emissions reduced in certain eligible Texas counties through the use of idle-reduction technology, including idle-limiting devices (Texas Commission on Environmental Quality, "Emissions Reduction Incentive Grant: Supplemental Activity Application Forms – Locomotive" ). These devices achieve their maximum benefit in warm climates, since locomotives typically must be kept running in cold weather to keep the engine from freezing up. However, locomotives can be fitted with systems that monitor key operating parameters (such as engine coolant temperature) in cold weather, and automatically restart the engine as needed.
  • Truck Stop Electrification – Truck stop electrification (TSE) is basically akin to shore power for trucks. Since Federal Motor Carrier Safety Administration and state agencies limit the number of consecutive hours drivers may operate commercial motor vehicles and/or be on duty, drivers often rest at truck stops or rest areas (Federal regulations require truckers to take 10 hours of rest for every 11 hours on the road). Truckers have historically left their vehicles idling during these rest stops for comfort purposes (air conditioning and heat), but idling a truck engine burns almost one gallon of fuel per hour. TSE systems allow truck drivers to instead use electric power for in-cab heating, air conditioning, and other functions. A number of private companies offer TSE technology for fleet owners, independent truck owner-operators, and travel plazas. The systems can be as simple as an extension cord hookup running from a parking space power station into the truck cab. Other systems use a window hookup to provide climate control, power outlets, Internet access, and other amenities. Some trucks are now being built with TSE hookups; others can be retrofitted to accept the appropriate connections. One limitation of this strategy is that there is limited parking at truck stops so many truckers rest at decentralized locations such as rest areas or parking lots, which cannot be efficiently electrified. As of October 2008, less than three percent of the nation’s 5,000 truck stops were electrified (U.S. Department of Energy, Energy Efficiency, and Renewable Energy Information Center).
  • Auxiliary Power Units (APU) – Auxiliary power units are devices that are typically installed on trucks to power accessories and climate control systems while the truck is parked, without idling the main engine. They can be battery-powered, but most APU are small diesel generators. Since the APU is considerably smaller than the truck's engine, it has much lower emissions. APU also save fuel costs and reduce unnecessary engine wear. This technology requires a significant up-front cost on the part of the truck owner (the average is about $6,000 per truck); as a result, it is most likely to be adopted on newer trucks with sleeper cabs. Use of the technology will, therefore, likely expand as the nation's truck fleet turns over.
  • Regulations Prohibiting Excessive Idling – As of 2006, 14 states plus the District of Columbia, as well as many counties and municipalities, had anti-idling regulations (U.S. Environmental Protection Agency. Compilation of State, County, and Local Anti-Idling Regulations. April 2006). Usually, regulations make it illegal to idle a vehicle beyond a certain length of time, but there are normally exceptions for emergency vehicles, inclement weather, or other factors. These regulations are not always limited to commercial vehicles and also may apply to passenger vehicles. Typically regulations are written specifically for vehicles over a certain weight rating.

3.2.2 Congestion Mitigation

Traffic congestion increases transportation sector emissions because vehicles idling in traffic emit more than those traveling at a steady speed. Efforts to alleviate congestion, therefore, can have a positive impact on emissions, including those from commercial vehicles. This section will focus on efforts specifically targeted towards reducing congestion associated with freight vehicles, but many of these improvements also benefit the traveling public.

  • Arterial Signal Coordination on Routes with High Truck Traffic – Adjusting signal timing to optimize traffic flow on routes with a high percentage of trucks is one way to help minimize freight emissions. A truck traveling at 55 mph that must stop at an intersection and then reaccelerate loses 60 to 80 seconds, as do passenger cars traveling behind the truck Eyler, D. "Traffic Responsive Signal Coordination." Presentation given to the TRB Traffic Signal Systems Committee, July 2003). Time spent idling at a traffic signal increases emissions, and reaccelerating increases them even more because the engine must work harder. Therefore, on certain arterial routes that experience heavy truck traffic, it can be beneficial to ensure efficient signal coordination to better facilitate traffic flow. There are signal systems available that can detect the presence of trucks in the traffic mix and adjust signal timing accordingly.
  • Port Access Improvements – Improving capacity at key access routes to seaports (either road or rail) can reduce emissions by minimizing wait times and queuing at the gates. Although these projects are rarely justified solely by their air quality benefits, the emissions reductions from potential access improvements can be quantified as additional benefits that can help move a project forward. The SR 519 Intermodal Access Project in Seattle (detailed in Section 5.2.2) was found to have numerous air quality benefits associated with reduced idling times for trucks and trains accessing the port.
  • Grade Separations for Road and Rail – Grade separation refers to physically separating two or more transport corridors to eliminate conflicts between traffic traveling in different directions. It most often refers to the separation of railroad tracks that cross highways, but also can be applied to rail/rail crossings. Highway/rail grade separations can limit emissions from cars and trucks that must stop and wait for trains to pass. They can, therefore, reduce vehicle emissions that are attributable to freight movements while mitigating passenger vehicle congestion at the same time. A rail/rail grade separation (such as the proposed Colton Crossing project in California, discussed in Section 5.2) directly reduces locomotive emissions since trains no longer have to stop for other trains going through the intersection.
  • Rail Infrastructure Improvements – Making improvements to rail line capacity and infrastructure can reduce freight rail emissions on corridors with heavy train traffic. Upgrading a single track corridor to double track, for instance, eliminates the need for one train to stop at a siding to allow another train to pass. Similarly, improving a rail tunnel to allow double-stacked container cars increases the volume of freight that can be moved by one train, thereby allowing the railroad to reduce the number of trains it operates or, conversely, increase the amount of freight hauled without increasing the number of trains. This is especially important since intermodal rail traffic has been growing much faster than traditional carload traffic over the past several decades. The Heartland Corridor Clearance project is one example of rail capacity improvements that have an ancillary air quality benefit. The project involves track and tunnel modifications that will allow double-stacked container trains to travel between Hampton Roads, Virginia and Columbus, Ohio on a Norfolk Southern rail corridor. Once complete in mid-2010, the upgrades will improve air quality by allowing greater cargo volume on the same number of trains while eliminating the current circuitous route that double-stacked trains must take to get between these points. The project is being funded through a public/private partnership (PPP) between Norfolk Southern, the U.S. DOT, the Virginia Department of Rail and Public Transportation, and the Ohio Rail Development Commission (PPP arrangements are increasingly common in rail infrastructure projects because most of the "easy" rail capacity improvements have already been built, leaving only the expensive mega-projects that railroads have difficulty funding through their own cash flow).
  • Truck-Only Lanes – A few states have experimented with freeway lanes wholly or partially devoted to trucks. By separating trucks from other traffic, truck-only lanes can improve traffic flow (which reduces emissions) and enhance safety. In the United States, this technique is used most often on short highway segments in dense urban areas that have a lot of truck traffic, or that link a port to the regional/national highway system. Though this technique is not widespread in the United States, there are a few examples of truck-only lanes. California was an early adopter of the strategy, and there are now two truck-only lanes (on I-5 in Los Angeles and Kern counties) in operation with more under consideration. Trucks are required to travel in the truck-only lanes, which are marked with black and white signs; automobiles are encouraged to travel in the other lanes, but are permitted to use the truck lanes. The Tchoupitoulas Corridor improvements at the Port of New Orleans included truck-only lanes to provide efficient access to the port while removing heavy truck traffic from surrounding neighborhoods; the lanes are specifically built to handle the stresses created by heavy truck traffic. In addition, although not a true example of truck-only lanes, a 34-mile segment of the New Jersey Turnpike provides a "dual-dual alignment," in which interior express lanes are reserved for auto-only use and exterior lanes for use by all traffic. A study conducted by the Southern California Association of Governments found that truck only lanes are most feasible under the following conditions:
    • Trucks make up 30 percent or more of the traffic mix;
    • Peak-hour traffic volumes are greater than 1,800 vehicles per lane-hour; and
    • Off-peak traffic volumes are more than 1,200 vehicles per lane-hour (Southern California Association of Governments and KAKU Associates, SR 60 Truck Lane Feasibility Study: Final Report, November 2000).
  • Short-Sea Shipping – Short-sea shipping is the movement of goods by water on routes that do not cross an ocean. It is being used in some areas as a strategy to reduce highway congestion by shifting some freight to marine modes via coastal shipping. The United States Maritime Administration (MARAD) recently launched a Marine Highways program to promote increased use of domestic waterborne transportation, including short-sea shipping. The Energy Independence and Security Act of 2007 directed the U.S. Department of Transportation to create a program to expand the use of Marine Highways by designating certain corridors as extensions of the surface transportation system and supporting projects that relieve congestion and improve air quality (http://www.marad.dot.gov/ships_shipping_landing_page/mhi_home/mhi_home.htm). Short-sea shipping already is used extensively in coastal regions, primarily for bulk commodities like aggregates and fertilizer that are not time-sensitive. One study on the West Coast found that there already was considerable short-sea carrying capacity on vessels making port rotations, but that high terminal and drayage costs would limit the adoption of this mode for coastal shipments (International Mobility Trade Corridor and Cambridge Systematics, Inc. Cross Border Shortsea Shipping Study, May 2004). Capital costs to start up short-sea shipping services also can be a barrier, due in part to Federal requirements (Jones Act) to buy U.S. built vessels for domestic shipping – which can double or triple the cost of acquiring vessels, as compared to foreign-built vessels (U.S. Department of Transportation, 2006, Four Corridor Case Studies of Short-Sea Shipping Services: Short-Sea Shipping Business Case Analysis, prepared by Global Insight for U.S. DOT Office of the Secretary, August 15, 2006). Variations of this strategy include efforts to shift freight to container-on-barge and truck-on-barge modes. Although short-sea shipping has the potential to alleviate pollution and congestion, it can be difficult for it to compete with trucks, particularly for more valuable, time-sensitive commodities.

3.2.3 Operational Changes

Freight generators (such as ports and freight-dependent business) and transportation agencies also can change their operating practices in ways that reduce emissions. These strategies can be implemented through regulation, use of new technology, or partnerships with the private sector.

  • Freight Vehicle Speed Reduction Programs – In order to minimize transit times, freight vehicles typically travel as fast as economically practicable within legal limits. However, vehicles exceeding their most fuel-efficient speed also emit more pollutants per mile traveled. Some jurisdictions have responded by implementing programs to reduce the speed of freight vehicles. These efforts are usually targeted at two modes:
    • Marine vessels – Some ports are now requiring vessels to reduce their speed when they come within a certain distance of shore. As in many areas of emissions reduction, California is a leader in the implementation of this strategy. The Ports of Los Angeles and Long Beach have a voluntary speed reduction program in which vessels approaching the port are encouraged to reduce their speed to 12 knots within 20 nautical miles of Point Fermin. Although most ships still operated above 12 knots after the program went into effect, data collected by the Port showed a significant reduction in average ship speeds (from 16 knots to about 13) (Garrett, T.L. "Voluntary Commercial Cargo Ship Speed Reduction Emission Reduction Program." Presentation to the CARB Marine Technical Resources Group, December 6, 2001). The California Air Resources Board currently is exploring ways to implement a statewide initiative, either voluntary or regulatory.
    • Trucks – Truck speed reduction can be accomplished in a number of ways, including driver training and electronic engine controls. Studies have found that tractor-trailers operating at 55 mph consume up to 20 percent less fuel than trucks driving at 65 mph (U.S. Environmental Protection Agency SmartWay Transport Partnership, "A Glance at Clean Freight Strategies: Reducing Highway Speed," February 2004). This not only reduces emissions, it also saves on fuel and maintenance costs, which can outweigh productivity losses incurred by operating trucks at slower speeds. New truck engines are usually already electronically controlled and trucks can be custom ordered with maximum speed settings built in; existing engines also can be retrofitted with governors (electronic devices that limit maximum speed). Many fleet managers opt to combine this technology with driver training to encourage lower speeds (Recent increases in the price of diesel fuel combined with growing corporate environmental awareness has encouraged more trucking firms to adopt these strategies in recent years).
  • Driver Training – There are numerous driving techniques (in addition to lower speeds) that truckers can employ to reduce emissions and save fuel. Effective trip planning (including alternate routing in the case of construction or emergencies), avoiding rapid acceleration and deceleration, and up shifting as soon as practicable are all ways that drivers can improve fuel economy while reducing freight vehicle emissions. Many trucking firms employ incentive programs that pay drivers bonuses for conserving fuel; engine monitoring systems can be employed to track performance and make recordkeeping easier.
  • Reduced Pickup and Drop-Off Idling for Trucks – Minimizing time spent idling during pickups and deliveries is another way to reduce emissions, particularly for delivery trucks operating in urban areas where they are likely to make several stops each day. Many freight-generating businesses have adopted no-idle policies at loading facilities in partnership with the EPA through the SmartWay Transport program (SmartWay is a cooperative program run by EPA that advises companies in the freight sector on how to reduce their emissions and fuel consumption). Some seaports, including Los Angeles and Long Beach, have implemented gate appointment systems whereby truckers are given a specific time window to pick up a container from the terminal. This strategy reduces unnecessary truck idling at the port gates. Gate appointment systems can be particularly effective since most of the drayage trucks used to move containers short distances (for example, from the port to an intermodal rail yard) are older and more polluting.
  • Off-Peak Cargo Moves – Another option is to encourage off-peak cargo moves, to reduce congestion and idling both at the port gates and on nearby roadways. The PierPASS/OffPeak program at the Ports of Los Angeles/Long Beach implements such a program by imposing peak-hour fees on cargo handled at the ports (the fees are then used to staff the port during off-peak hours), and providing refunds for loads handled at off-peak hours. However, the effectiveness of off-peak incentives can be limited by customer business hours; many businesses are only open to accept deliveries during the daytime.
  • Improved Port Operational Strategies – There also are port operational strategies that can be employed inside the terminal gates to reduce truck VMT and emissions. Some container terminals now require trucks to be fitted with radio frequency identification (RFID) tags so that the position of the truck can be monitored within the terminal, enabling terminal operators to better direct truckers to the appropriate place to pick up their cargo. Another strategy is to maintain a chassis pool for truckers who are dropping off or picking up containers for more than one shipping line. Most terminals own their own fleet of container chassis, so when a trucker needs to pick up his next load from another terminal he usually must find another chassis owned by the second shipping line. A shared pool of chassis eliminates this problem. The Port of Virginia, for example, contracts with a third party to maintain a chassis pool.
  • Weigh Station Bypass – Most states weigh trucks operating on major highways to ensure that they are not violating weight restrictions. While this is a necessary function to help prevent excessive pavement and bridge deterioration, it also results in emissions from idling trucks in the weigh station queue. There are two techniques that state DOTs and public safety agencies can adopt to eliminate this problem:
    • Virtual Weigh Station/Smart Roadside. Virtual weigh stations, or high-speed weigh-in-motion screening, are remote, unstaffed weigh stations. Typically, weigh-in-motion devices measure and record truck axle weight and gross vehicle weight as the vehicle moves over a sensor installed in the pavement, while a camera is used to identify the vehicle. This information is used to make a screening decision on whether the vehicle should be intercepted (by an enforcement officer) for weighing or inspection. Such systems prevent unnecessary idling at weigh stations and provide continuous data rather than the sample data collected at static weigh stations. They also can minimize scale avoidance, since drivers may not know where the VWS is set up.
    • Electronic credentialing services allow trucks equipped with special transponders to bypass weigh stations, port-of-entry facilities, and agricultural inspection stations. For instance, PrePass, one of the most widely available such systems (currently in 29 states), monitors vehicle credentialing and safety and can be used in conjunction with weigh-in-motion devices to ensure compliance with weight requirements.
  • Reduced Empty Mileage – Empty mileage refers to unloaded truck or rail car movement. This is doubly important to freight carriers, since an empty vehicle incurs costs without earning revenue. Trucking firms and owner-operators can combat this problem in a number of ways, such as hauling loads in a triangular pattern, coordinating with other companies to find backhaul opportunities, purchasing better routing software, and using load-matching sites on the Internet. Implementing flexible shipping and receiving schedules (e.g., 24/7 shipping and receiving) can minimize idling and loading times by avoiding peak hours, but this must be closely coordinated with customers. Rail backhaul is much more difficult because of the inflexible nature of rail routing, but can be accomplished with close coordination between two or more shippers and the railroads serving them.
  • Reduction of Circuitous Train Routing – Freight trains have very limited routing options because of the fixed nature of their routes and the high capital costs of building new rail corridors. As a result, trains must often take circuitous routes to get between two points, particularly when operating over tracks owned by another railroad through a lease arrangement. The Heartland Corridor Clearance project (described previously) is an example of a capacity project that eliminates a circuitous train route.
  • Construction or Expansion of Truck/Rail Intermodal Facilities – Truck/rail intermodal transportation combines traditional trucking with line-haul rail service, maximizing the advantages of both modes (lower cost for rail, speed/route flexibility for trucks). In recent years, escalating fuel costs have created more demand for intermodal services, which in turn necessitates the construction or expansion of intermodal facilities to handle the transfer of goods between truck and rail. The Class I railroads have built several new intermodal yards around the country, often with support from local and/or state governments that recognize the economic development and job creation benefits associated with them. For example, BNSF is building a new intermodal facility in Gardner, Kansas, about 25 miles southwest of Kansas City. The yard is the third in a series of 'logistics parks' operated by BNSF in which warehouses and distribution centers are developed adjacent to an intermodal rail yard so that companies can better take advantage of efficient freight rail service. Johnson County and the City of Gardner are making strategic road improvements around the facility, while the Kansas Department of Transportation is improving a key interchange on I-35 that will serve the intermodal terminal. Although much of the activity at the facility will simply be relocated from Kansas City, the new terminal will use electric-powered container handling equipment instead of the diesel-powered vehicles in use at the existing Kansas City yard. In addition, reduced congestion at the new facility is expected to create air quality benefits for the region. If located properly, intermodal yards offer the chance to move goods closer to their final destination via rail or ship (which consume less energy on a ton-mile basis) and then use trucks for the final short-haul trips.
  • Truck Fleet Operational Strategies – There are a number of strategies that truck fleet owners and manager can employ to reduce transportation expenses which often also reduce fuel consumption and, therefore, emissions. Better alignment of supplier ship points to distribution centers, moving more cargo per trailer, reducing or eliminating unnecessary packaging, and just-in-time logistics all help to minimize distance traveled and/or fuel use. By combining shipments, firms can employ the least-cost transportation option (for example, less-than-truckload shipping is more expensive than truckload, which in turn is more expensive than intermodal). This can be accomplished by combining multiple purchase orders, synchronizing order days, and establishing consistent lead times across company departments shipping from the same location. Knowing the weight and dimensions of items to be shipped helps maximize trailer productivity.

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