Potentials for Platooning in US Highway Freight Transport
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Potentials for Platooning in U.S. Highway Freight Transport Preprint Matteo Muratori, Jacob Holden, Michael Lammert, Adam Duran, Stanley Young, and Jeffrey Gonder National Renewable Energy Laboratory To be presented at WCX17: SAE World Congress Experience Detroit, Michigan April 4–6, 2017 To be published in the SAE International Journal of Commercial Vehicles 10(1), 2017 NREL is a national laboratory of the U.S. Department of Energy Office of Energy Efficiency & Renewable Energy Operated by the Alliance for Sustainable Energy, LLC This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. Conference Paper NREL/CP-5400-67618 March 2017 Contract No. DE-AC36-08GO28308 NOTICE The submitted manuscript has been offered by an employee of the Alliance for Sustainable Energy, LLC (Alliance), a contractor of the US Government under Contract No. DE-AC36-08GO28308. 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Box 62 Oak Ridge, TN 37831-0062 OSTI http://www.osti.gov Phone: 865.576.8401 Fax: 865.576.5728 Email: [email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5301 Shawnee Road Alexandria, VA 22312 NTIS http://www.ntis.gov Phone: 800.553.6847 or 703.605.6000 Fax: 703.605.6900 Email: [email protected] Cover Photos by Dennis Schroeder: (left to right) NREL 26173, NREL 18302, NREL 19758, NREL 29642, NREL 19795. NREL prints on paper that contains recycled content. 2017-01-0086 Potentials for Platooning in U.S. Highway Freight Transport Matteo Muratori, Jacob Holden, Michael Lammert, Adam Duran, Stanley Young, and Jeffrey Gonder National Renewable Energy Laboratory CITATION: Muratori, M., Holden, J., Lammert, M., Duran, A. et al., “Potentials for Platooning in U.S. Highway Freight Transport,” SAE Int. J. Commer. Veh. 10(1):2017, doi:10.4271/2017-01-0086. Abstract Platooning is a demonstrated method of groups of vehicles travelling close together actively coordinated in formation at high speed that has the potential to reduce energy consumption resulting from Smart technologies enabling connection among vehicles and between aerodynamic drag [2] [3]. Trucks are ideal applications for platooning vehicles and infrastructure as well as vehicle automation to assist due to their technical characteristics and mode of operation (several human operators are receiving significant attention as a means for vehicles driving for long distances along the same route, often improving road transportation systems by reducing fuel consumption concentrated in few corridors). – and related emissions – while also providing additional benefits through improving overall traffic safety and efficiency. For truck applications, which are currently responsible for nearly three-quarters Combination trucks, currently powered by petroleum-derived fuels, of the total U.S. freight energy use and greenhouse gas (GHG) account for the majority of the energy use in the U.S. freight sector emissions, platooning has been identified as an early feature for (64.9% of freight, and 4.8% of total U.S. energy use in 2013 [4]) and connected and automated vehicles (CAVs) that could provide an even larger share of GHG emissions (77.1% of freight, and 7.5% significant fuel savings and improved traffic safety and efficiency of total U.S. GHG emissions in 2013 [5]). Looking at the future, the without radical design or technology changes compared to existing importance of trucking on the U.S. energy use and GHG emissions is vehicles. A statistical analysis was performed based on a large likely to increase, due mainly to three factors: a) freight transport has collection of real-world U.S. truck usage data to estimate the fraction been growing more rapidly than passenger transport, and the trend is of total miles that are technically suitable for platooning. In likely to continue in the future [6] [7]; b) a continued increase in the particular, our analysis focuses on estimating “platoonable” mileage share of trucking in total freight activity [8] [9] [10]; c) based on overall highway vehicle use and prolonged high-velocity transportation, and freight in particular, is more expensive to traveling, and established that about 65% of the total miles driven by decarbonize compared to other sectors, and will experience lower combination trucks from this data sample could be driven in platoon energy and GHG emissions reduction in response to economy-wide formation, leading to a 4% reduction in total truck fuel consumption. climate change mitigation measures [11]. This technical potential for “platoonable” miles in the United States provides an upper bound for scenario analysis considering fleet Several studies, reviewed in the Methods section, have been focusing willingness and convenience to platoon as an estimate of overall on assessing the potential savings achievable by platooning benefits of early adoption of connected and automated vehicle operations for a group of two or more trucks, as well as extrapolating technologies. A benefit analysis is proposed to assess the overall these savings on a national scale, based on overall miles traveled by potential for energy savings and emissions mitigation by widespread trucks. However, a key element has been neglected in the existing implementation of highway platooning for trucks. literature: what is the “platoonable” fraction of traveled miles during real-world operations? Namely, in a fleet of trucks, what fraction of miles driven is amenable for platooning operation? Clearly not every Introduction mile driven can be driven in a platoon formation, and platooning operations at low speeds do not lead to significant fuel saving. Connected and automated vehicles (CAVs) are receiving significant However, for large trucks operating extensively on highways over attention as a technology solution to realize safer, more cost- long distances the fraction of platoonable miles at high speed can be effective, and efficient operation of several transportation systems significant (in estimating the potential savings related to trucks [1]. CAVs can also potentially help curb energy consumption and platooning, MacKenzie et al. [12] assume that every mile traveled by greenhouse gas (GHG) emissions from the transportation sector. In trucks is platoonable, leading to significantly different results 1 this paper we focus on the role of platooning for combination trucks compared to this study). in the United States, one of the most promising CAV technologies that could experience widespread adoption in the next 5 to 10 years. We provide an estimate of the platoonable fraction of miles driven by combination trucks in the United States based on a large set of driving data collected by the National Renewable Energy Laboratory 1 Combination trucks include Class 7 and Class 8 trucks, as defined by the (NREL) and others. This data set includes over 3 million miles of U.S. Federal Highway Administration. Class 8 trucks, which are the majority driving data across a variety of fleet operators, truck manufacturers, of combination trucks, are vehicles with a gross weight rating exceeding times of operation, and regions. In particular, we assume that a truck 33,001 lbs (14,969 kg). Class 8 includes tractor-trailer tractors as well as could potentially operate in a platoon if it continuously travels at a single-unit dump trucks. The typical 5-axle tractor-trailer combination, also called a "semi" or "18-wheeler,” is a Class 8 vehicle. speed larger than a certain threshold for a significant period of time. A sensitivity analysis shows that the velocity and the time threshold 1 This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications significantly impact the resulting fraction of platoonable miles. These Table 1 summarizes the data set considered, while Figure 1 and thresholds have been chosen to be 50 mph (80.5 km/h) and 15 Figure 2 show the distribution of all the trips included in the data set minutes for representative operations in the United States. based on trip length and duration, respectively. Trips shorter