There are many available technologies that can be applied to reduce the fuel consumption of trucks, but there are other ways of saving fuel that do not require any changes to vehicle or engine technologies. The overall fuel consumption of a truck fleet can be influenced significantly by the ways in which the vehicles are operated and maintained. Factors such as how close to full payload the trucks operate, whether they run on the most efficient routes, and even driver training can play a role in determining overall fleet fuel consumption. In addition, regulations can directly affect fuel consumption by constraining or promoting technology implementation and efficient operations. The infrastructure on which trucks operate also affects fuel consumption, through factors such as speed fluctuation and congestion. Electronic features can be added to the truck to modify the performance of the engine or vehicle in ways that can save fuel. All of these possibilities fall under the category of “efficient operations.” The U.S. Department of Energy (DOE) and the U.S. Department of Transportation (DOT) proposed efficient operations as a new area for work under the 21st Century Truck Partnership (21CTP) in 2011. At that time no programs or work had been initiated in the 21CTP in this new area. The 21CTP’s proposal for work on efficient operations was initially laid out in a February 2011 draft white paper, “Reducing Fuel Consumption in U.S. Trucking—A DOE-DOT Joint Study and Whitepaper” (DOE-DOT, 2011). In this draft, the two agencies explored opportunities to improve the efficiency of trucking operations. The paper focused on two areas:
- Opportunities for joint research and development (R&D) effort between the DOE and the DOT and
- Opportunities for modifying regulations (primarily DOT regulations) in ways that could permit more efficient operations.
The draft white paper became available just as the National Research Council (NRC) Phase 2 report (NRC, 2012) was being prepared. The Phase 2 committee devoted Chapter 9 of that report to a review of the draft white paper, as well as suggestions for improvement. Chapter 9 of the NRC Phase 2 report provided information on numerous approaches to making operations more efficient:
- Vehicle maintenance;
- Optimization of packaging for goods to be shipped, to increase the number of units per truckload;
- Load management optimization;1
- Route optimization;
- Supply chain optimization to limit the amount of shipping required;
- Infrastructure improvements;
- Application of Intelligent Transportation Systems (ITS);
- Expanding driver training to include fuel efficiency;
- Applying driver management controls features; and
- Reconsideration of regulatory constraints.
The NRC Phase 2 report recommended a number of changes to the draft white paper, to broaden its scope and include more areas of potential cooperation among the agencies. For example, research on ITS usually does not take freight efficiency into account, although this can be a significant benefit of ITS applications. The Phase 2 report recommended consideration of high-productivity vehicles, with higher weight limits and/or larger cubic capacity. The MAP-21 project on truck size and weight is now exploring some of these options. Finally, the Phase 2 report recommended that specific productivity goals be set in the final version of the white paper.
1 Load management refers to efforts by trucking companies to ensure that trucks run as close to full payload as possible over the shortest distance needed to make deliveries.
In February 2013, the Partnership issued an updated roadmap and technical white papers (21CTP, 2013). Goals were stated for the areas of interest for the Partnership. Many of the approaches to making operations more efficient identified in the Phase 2 report and listed above were included in the white paper. Areas not addressed in the white paper include vehicle maintenance, optimization of packaging, load management optimization, route optimization, and infrastructure improvements. The goals from the February 2013 white paper for efficient operations are repeated below, along with the understood progress toward each goal.
Goal: Minimizing Impact of Driver Behavior for Optimal Acceleration
Develop and demonstrate technologies that minimize the impact of driver behavior for optimal acceleration efficiency by automatically controlling vehicle accelerations at a level for which the engine operates in its most efficient operational state for the current environment. Driver feedback information devices can also be implemented as a retrofit option for existing vehicles.
This goal has been met. Various vehicle acceleration control products are available today in the U.S. heavy-duty industry. One such product from Cummins is SmartTorque2 and Vehicle Acceleration Management (VAM). SmartTorque2 automatically senses vehicle weight, grade, and operating gear and then selects the optimum torque for the best fuel consumption and performance in every gear. VAM is a unique electronic feature that is enabled on Cummins ISX15 ST2 engines in the SmartAdvantage Powertrain. It controls the acceleration rate from the launch of the vehicle, maintaining more consistent acceleration for a more efficient transition through the gears. Cummins claims that VAM results in smoother acceleration and reduced driveline wear, while improving fuel consumption (Cummins, Inc., 2013).
Industry has introduced products that go beyond acceleration control to improve fuel consumption. These are referred to as predictive adaptive cruise control. Simply stated, these products use knowledge of the vertical terrain via loaded or learned maps and the Global Positioning System (GPS) to control the engine and transmission to optimize the use of vehicle kinetic energy. This approach is effective at improving fuel consumption in rolling or hilly terrains. Such products include Volvo’s I-See, currently available in Europe, and Daimler’s new Intelligent Powertrain Management (IPM). Daimler Trucks North America announced on December 5, 2014, that IPM will be standard on all of Detroit Diesel Corporations’s DT12 automated manual transmissions paired with any heavy-duty Detroit Diesel engine, beginning in March 2015.2
Predictive adaptive cruise control technology is being used in all the SuperTruck projects as well. Additional features are being developed under SuperTruck, such as intelligent control of auxiliaries.
ITS technologies that reduce traffic congestion and improve traffic flow, as well as technologies such as adaptive cruise control, have good potential to reduce fleet fuel consumption.
Goal: Tools to Estimate Fuel Savings of Advanced Technologies
Develop simple tools for the trucking industry that will provide estimates of the fuel savings potential of advanced efficiency technologies and technology combinations depending on specific usage information of a particular fleet (measured drive cycle data). The tools will provide cost and benefit analyses for the selection of technologies on a case-by-case basis when representative drive cycles for an individual fleet or owner-operator are available (and recommendations to the fleet for obtaining the drive cycles can be provided).
The committee is not aware of any activity toward this goal under the Partnership. The committee is aware that all the major OEMs have very sophisticated tools that can take duty-cycle data and payload data and use it to optimize a vehicle specification for a given customer. These tools are widely used to optimize vehicle specifications for customers. As a result of this situation, it may not make sense for government agencies to invest in the development of additional tools.
Goal: ITS/Connected Vehicle Technologies to Reduce Fuel Consumption
Conduct a study to identify proposed ITS/connected vehicle technologies that offer significant fuel savings and quantify the reduction in fuel consumption for technologies that offer the greatest benefits. Select one technology, evaluate the benefits for fuel consumption as a function of market penetration and identify the infrastructure needs and costs for deployment of the technology to a level at which the benefits of vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) networking are realized.
2 Detroit Diesel Corporation is a subsidiary of Daimler Trucks North America.
The National Renewable Energy Laboratory (NREL) and Peloton have conducted controlled testing to evaluate the fuel economy improvement potential provided by heavy truck “platooning” (DOE Project VSS001; Walkowicz et al., 2014). SAE J1321 Type II fuel economy tests were performed under controlled track conditions. Two platooned SmartWay tractors were used: 2011 Peterbilt 386 line haul sleepers with Cummins ISX 450 engines. The two trailers were 53-ft van bodies with side skirts. The testing was conducted at 55, 65, and 70 miles per hour (mph), with vehicle gaps from 20 to 75 ft and gross vehicle weights (GVWs) of 65,000 and 80,000 lb. Fuel savings were seen with both the lead and following tractor-trailers (truck). The best “team” fuel saving was 6.4 percent at 65,000 lb, 55 mph, and 30 ft following distance. The lead truck saw increasing benefit with closer following distances at all speeds. The savings ranged from 1.7 to 5.3 percent at 65,000 lb. The trailing vehicle saw savings of 2.8 to 9.7 percent at 65,000 lb. Savings on the trailing truck were reduced at the closer following distances due to a higher percentage of engine fan-on time. The authors comment that in order to maximize the savings for the trailing truck, the following distance should be adjusted based on coolant temperature to minimize the engine fan-on duty cycle.
It can be concluded that line-haul fuel savings are possible through platooning. Such close following distances for heavy trucks raise safety concerns so that additional study and testing are required to address this concern. V2V communication should greatly improve the safety aspects of platooning.
Look-Ahead Driver Feedback and Power Train Management
The objective of this project is to develop and demonstrate on real vehicles a driver assistance technology to reduce commercial fleet average fuel consumption by at least 2 percent (DOE Project VSS087; Verma, 2014). In this project, information from various sources, including radar, V2I, V2V, GPS, the vehicle data bus and a three-dimensional digital map are fed to an “intelligent driver assistance system.” The system, through recognition of the environment and driver behavior, will estimate optimal fuel consumption behavior. A combination of power train control and advisory feedback provided to the driver via a human-to-machine interface (HMI) will maximize fuel savings with minimal distraction. The HMI algorithm and hardware have been developed and built. The data acquisition system is integrated and the entire system has been installed and validated on a prototype vehicle. The project has partnered with Con-Way to install and evaluate the system on two pilot vehicles. Preparation of the pilot vehicles is in progress.
Connected Vehicle Program
The Connected Vehicle program at DOT (ITS Joint Program Office) has several aspects that touch on 21CTP interests. A prime example is the Crash Avoidance Metrics Partnership (CAMP), the “connected vehicles and infrastructure” pilot project recently concluded in Ann Arbor. This 2012-2014 field project followed 16 heavy trucks and 3 buses fitted with safety warning equipment to avoid crashes. No fuel efficiency or derivative data were collected in Phase I of that pilot project. However, future embodiments of the research will be conducted under the University of Michigan’s Mobility Transformation Center, and the scope will be broadened to include DOE input on desired measures of performance. It appears that the scope of the Connected Vehicle Program could be broadened to include commercial vehicle fuel consumption.
Goal: A Real-World Test Corridor to Improve Vehicle Operations
Establish a real-world test corridor for commercial vehicles focused on improving commercial vehicle operations, including fuel efficiency. The test corridor could have infrastructure content such as DSRC (dedicated short range communication) and Wi-Max technologies, to provide an environment compatible with future V2I communications. The concept would involve one or more fleets enabled for DSRC/Wi-Max capability and outfitted with various applications designed for improved efficiency of commercial vehicles.
The committee is not aware of any Partnership activity addressing this goal.
Goal: Regulatory Changes to Replace Mirrors with Cameras
- Explore regulatory changes to permit the replacement of body-mounted mirrors with a camera-based system and quantify the fuel saving benefits associated with such a change.
- Quantify the fuel consumption penalty imposed by mirror regulations on highway-based commercial vehicle operations.
- Develop safety and robustness requirements for camera-based systems and conduct human factors research to develop and demonstrate equivalent safety of a camera-based system.
3 Platooning refers to a convoy of two or more trucks linked electronically with an active driver in each.
- Assess procedural requirements for implementing the necessary regulatory changes and quantify the efforts required to modify regulations to permit camera-based systems in place of mirrors for Class 8 long-haul vehicles.
The committee is not aware of any Partnership activity with this as a goal. A report by the Truck Manufacturers Association (NETL, 2007) shows that replacing mirrors with cameras has the potential to reduce fuel consumption at high-speed cruise by up to 3 percent, depending on the type of mirrors being replaced. The truck size and weight study being conducted under MAP-21 is examining triple trailer configurations (FHWA, 2014). The study will address fuel savings, safety, infrastructure, and potential freight diversion.
Goal: Use of Long Combination Vehicles
- Demonstrate the fuel savings benefits and develop policy guidelines for extending the use of long combination vehicles (LCVs), particularly triple-trailer units.
- Complete long-term in-fleet measurements to quantify the fuel savings of triple-trailer combination vehicles in comparison with single- and double-trailer operations in the same fleet, on a load specific fuel consumption basis (LSFC).
- Conduct an analysis to quantify the fuel savings if triple trailers are permitted on all interstate highways in the United States.
The committee is not aware of any active programs with this goal under the Partnership.
Goal: Improved Supply Chain Management Strategies
- Promote improved supply chain management strategies in the commercial freight industry with an objective to increase the loads carried per truck and reduce vehicle miles traveled (VMT).
- Conduct a study to identify fleet best practices for supply chain management, and quantify the fuel savings that are achieved with efficient fleet operations vs. operations of fleets that do not have streamlined supply chains.
The committee is not aware of active programs toward this goal under the Partnership. Since there is considerable commercial incentive to improve supply chain management, there is a lot of activity by the trucking industry on this topic. As such, it is not clear that this is an appropriate area for government-sponsored research.
In this section the recommendations made by the committee in the NRC Phase 2 report and the Partnership’s responses are addressed.
NRC Phase 2 Recommendation 9-1. As suggested in the draft white paper on efficient operations, the DOE and DOT, in cooperation with the EPA and other agencies, should conduct joint research on efficient operations and should cooperate as appropriate on any regulations that affect fuel use and safety.
21CTP Response: The Partnership is pleased that the NRC panel recognizes the significance of efficient operations and supports the objectives of this new white paper. The 21CTP concurs with the recommendation for joint DOE and DOT research in efficient operations, and members of the Partnership are committed to supporting this effort. The Partnership is also interested in identifying opportunities for streamlining regulations that can improve operational efficiencies to achieve maximum benefit while maintaining or improving safety and other areas of operation.
Committee Comment on Response to 9-1
This response is quite positive, and various goals were established in the Partnership’s February 2013 white paper.
NRC Phase 2 Recommendation 9-2. The available data show that trailer aerodynamic-improvement features and rolling resistance contribute significantly to overall vehicle fuel consumption. Therefore, the DOE and DOT should look in detail at options for trailer improvement.
21CTP Response: The Partnership agrees with the recommendation and supports research to quantify the fuel savings benefits of trailer technologies in addition to tractor-based technology improvements. A systems approach that considers all components of the vehicle is expected to provide the greatest benefits, and the Partnership understands the gains that can be achieved from trailer technologies and promoting their use and further development is a worthwhile pursuit. The DOE and DOT are committed to better understanding the real world fuel savings offered by advanced technologies for both tractors and trailers. For example, the DOE conducted a long-term in-fleet study in which new generation wide base single (NGWBS) tire fuel efficiency benefits were evaluated on both tractors and trailers. Such studies are very helpful in promoting the benefits of these technologies, and the Partnership supports the continuation of this type of research.
Committee Comment on Response to 9-2
The response gently sidesteps the actual recommendation regarding trailer aerodynamic and rolling resistance features. However, the SuperTruck participants are seriously pursuing improvements in trailer aerodynamics and are demonstrating its beneficial effects on fuel consumption.
NRC Phase 2 Recommendation 9-3. Traditionally, ITSs have been viewed as a way of improving safety. As suggested in the draft white paper on efficient operations, the DOT and DOE should conduct additional research and development devoted to exploiting the potential for reduced fuel consumption.
Partnership Response: The Partnership agrees with the NRC panel’s finding and recommendation for further ITS-based R&D aimed at reducing fuel consumption. The 21CTP welcomes the opportunity to help advance this exciting new technology area to extend fuel savings even beyond what is possible with traditional engine and vehicle technologies. ITS technology is very unique in that it requires a strong infrastructure and participation of numerous vehicles before the full benefits can be realized, and the Partnership feels that its structure as a broad private-public partnership offers a unique opportunity to coordinate the development of critical infrastructure and standards while simultaneously deploying new technologies into the vehicle market.
Committee Comment on Response to 9-3
The Partnership’s response is quite positive but lacking in any specific goals or plans.
NRC Phase 2 Recommendation 9-4. The DOE and DOT should work with the trucking industry to take advantage of the ideas, data, and experience that the industry can provide to accelerate efficiency improvements and to avoid unintended negative outcomes of efforts to improve trucking efficiency.
Partnership Response: The Partnership concurs with this finding and recommendation. Any efforts aimed at improved logistics management and trucking operations must be performed in collaboration with the trucking industry to ensure that best practices are not violated and any new proposed solutions can be effectively implemented with minimal or no negative consequences on fleet operations, safety or road damage.
Committee Comment on Response to 9-4
The Partnership’s response is quite positive but lacking in any specific goals or plans.
NRC Phase 2 Recommendation 9-5. The DOT and DOE should look at the full range of high productivity vehicles in use in some U.S. states and around the world and review the literature available on the safety and fuel-saving performance
of these vehicles. The assessment should take into consideration that the higher productivity of these vehicles can also be used to justify the implementation of additional safety technologies.
Partnership Response: The NRC panel pointed out a number of important additional points concerning high productivity vehicle use that were not highlighted in the draft white paper on efficient operations. A more thorough literature review in the white paper is appropriate for this topic and is planned for the next version of the white paper.
Committee Comment on Response to 9-5
The Partnership’s response is quite positive, and while it provides a plan to address the issue, a more thorough literature review was not included in the February 2013 white paper. The white paper did establish a goal concerning the use of long combination vehicles (LCVs).
This recommendation is partially addressed by the Federal Truck Size and Weight study under Map-21. Provisions in MAP-21 require DOT to conduct a study addressing safety risks, infrastructure impacts, and the effect of enforcement for trucks operating at or within federal truck size and weight limits in contrast to more productive trucks legally operating in excess of federal limits. The fuel savings potential for these higher productivity vehicles is to be assessed, together with estimates of freight diversion from other modes that may occur as a result of their introduction. The study report was due to Congress by November 15, 2014, but is now anticipated in 2015.
NRC Phase 2 Recommendation 9-6. The DOT and DOE, in discussion with the Congress, should consider the recommendations of the Transportation Research Board regarding the establishment of a Commercial Traffic Effects Institute or a similar approach.
21CTP Response: The Partnership fully agrees with these findings and recommendations, including the consideration of recommendations made in TRB Special Report 267 (Transportation Research Board 2002). In particular the establishment of a Commercial Traffic Effects Institute.
Committee Comment on Response to 9-6
The Partnership’s response is quite positive but lacking in any specific plan.
NRC Phase 2 Recommendation 9-7. Specific goals for efficient operations should be developed, with strong consideration given to exploiting the potential for intelligent transportation systems to reduce fuel consumption. In addition, priorities should be set for the R&D, testing, and data collection needed to analyze the benefits, drawbacks, and potential unintended consequences of removing barriers, including regulatory barriers, to the application of fuel-saving features. The draft white
paper on efficient operations should be rewritten to take the findings and recommendations of the committee into account. The 21CTP partners, trucking fleets, and major suppliers should be involved in setting goals and research priorities.
Partnership Response: Although the draft white paper on efficient operations available at the time of the NRC’s panel review did not include goals on this topic, the Partnership has added a set of specific goals that are consistent with this recommendation. A further rewrite of the draft white paper is also planned that will address the panel’s recommendations. The Partnership is aware that many of the approaches proposed for efficient operations involve multiple complexities and agrees that detailed studied are needed to assess the benefits, drawbacks, and potential unintended consequences of removing barriers for efficient operations.
Committee Comment on Response to 9-7
As these goals are established they should have numerical targets and should be prioritized.
NRC Phase 2 Recommendation 9-8. The DOE and DOT should study the potential fuel savings from efficient operations in more detail, including a review of cost-effectiveness and ease of implementation. Once this information is available, goals, targets, and timetables for fuel savings from efficient operations should be established. Programs should then be developed and implemented to realize the available fuel savings.
21CTP Response: The Partnership agrees that research is needed to quantify the benefits as well as the costs and challenges of implementation associated with the proposed methods for efficient operations. Ultimately, the end goal is to implement these approaches for which the benefits clearly justify the costs, and the Partnership concurs with the NRC panel’s recommended course of action to arrive at this objective.
Committee Comment on Response to 9-8
In order to set specific goals and R&D priorities, it will be necessary to do some up-front research. The committee’s recommended project would quantify the potential benefits of various technologies on efficient operations, determine which ones are appropriate targets for government-funded research, and identify those technologies with the highest potential benefit.
Finding 9-1. The committee supports the effort by the Partnership to revise the Efficient Operations section of the February 2013 white paper to include specific goals for Efficient Operations. Unfortunately, activity and progress toward articulating these goals are limited.
Recommendation 9-1. In light of the limited activity in Efficient Operations, the Partnership should revisit, revise, and prioritize the goals to better reflect the areas where government-sponsored research can lead to significant fuel consumption improvements. A preliminary study may be needed to help set appropriate goals and priorities. 21CTP should revisit goals in two areas in particular: high productivity vehicles and expanded use of ITS to reduce fuel consumption.
Finding 9-2. As noted in Finding 9-3 of the NRC Phase 2 report, ITS technology holds considerable potential for improving fuel consumption in commercial vehicles.
Finding 9-3. The DOT’s Connected Vehicle Program phase 1 pilot program did not collect data on fuel efficiency or related derivative data.
Recommendation 9-2. DOT should expand the scope of its Connected Vehicle Program to measure the effects of various technology implementations on fleet fuel consumption. Once the potential for fuel savings is clarified, fuel savings targets should be set for future projects.
Finding 9-4. The close following distances that are required for vehicle platooning with heavy trucks raise safety concerns.
Recommendation 9-3. 21CTP should conduct additional study and testing to address any potential safety concerns associated with platooning of heavy trucks.
21CTP. 2013. 21CTP Roadmap and Technical White Papers (February). Washington, D.C.: Office of Vehicle Technologies. http://energy.gov/eere/vehicles/downloads/roadmap-and-technical-white-papers-21stcentury-truck-partnership. Accessed October 10, 2014.
DOE-DOT (Department of Energy-Department of Transportation). 2011. Reducing Fuel Consumption in U.S. Trucking–A DOE-DOT Joint Study and White Paper. 21st Century Truck Partnership Efficient Operations White Paper Draft of February 15, 2011. Washington, D.C.
FHWA (Federal Highway Administration). 2014. MAP-21 Comprehensive Truck Size and Weight Limits Study. http://www.ops.fhwa.dot.gov/freight/SW/map21tswstudy/index.htm. Accessed April 24, 2015.
NETL (National Energy Technology Laboratory). 2007. Test, Evaluation, and Demonstration of Practical Devices/Systems to Reduce Aerodynamic Drag of Tractor/Semitrailer Combination Unit Trucks. Prepared for the National Energy Technology Laboratory by the Truck Manufacturer’s Association, Contract DE-FC26-04NT42117, April.
National Research Council (NRC). 2012. Review of the 21st Century Truck Partnership, Second Report. Washington, D.C.: The National Academies Press.
Verma, R. 2014. Look-ahead Driver Feedback and Powertrain Management. Eaton Corporation. DOE Annual Merit Review VSS087. Washington, D.C., June 19.
Walkowicz, K., M. Lammert, A. Ragatz, A. Duran, and M. Simpson. 2014. Medium and Heavy Duty Vehicle Field Evaluations. National Renewable Energy Laboratory. DOE Annual Merit Review VSS001. Washington, D.C., June 17.