Could trucking lower operational costs by matching tractors to trailers?

Matching tractors to trailers could improve efficiency and lower costs for trucking fleets is among the concepts that vehicle engineers continue to chase, but the North American freight system might not be able to benefit from these advancements. (Photo: Jim Allen/FreightWaves)

With so many large fleets focused on drop-and-hook operations to maximize efficiency, there is little focus on matching tractors to trailers. But, a new report from the North American Council for Freight Efficiency (NACFE), says that a change in operations to allow for more “intentional pairing” of tractors and trailers could lower truck operating costs. How much it would take to entice fleets, though, is uncertain. NACFE suggests that a 5 percent to 10 percent net improvement could get the ball rolling.

The study, “The Feasibility of Intentional Pairing,” was undertaken by NACFE after a conversation with a truck manufacturer involved in the U.S. Department of Energy’s (DOE) SuperTruck II project. The concept is an engineer’s dream, allowing for the design of an integrated tractor-trailer combination in the most efficient way possible. This approached heavily influenced the Shell Starship prototype vehicle and is the basis for the ongoing DOE SuperTruck II project.

“One of the things that always comes up when engineers are designing tractors and trailers is they say, ‘if we could only know that the trailer would stay with the tractor for [all of its] life,’” Mike Roeth, executive director of NACFE, said.

The 86-page report dives into great detail around the equipment as well as additional factors such as e-commerce that guide the design and development of modern tractor-trailers. In addition to research from available public data and its own database, NACFE sent a survey to 50 fleets. Among those that responded were  Bison, CFI, Hirschbach, Maverick, NFI, Nussbaum, PepsiCo (NASDAQ: PEP), Ryder (NYSE: R), Schneider (NYSE: SNDR), UPS (NYSE: UPS), Werner (NASDAQ: WERN) and others representing a “significant sampling of freight industry operations.” NACFE also consulted with owner-operators such as Henry Albert, and with experts at ACT Research and Let’s Truck’s Kevin Rutherford.


To no great surprise, NACFE found that the majority of fleets pull dry van and 53-foot refrigerated trailers and operate in drop-and-hook operations with the focus on keeping the trailer moving as much as possible.

“We concluded there is not a lot of opportunity to intentionally pair tractors and trailers,” Roeth said.

The report did find that intentional matching a tractor to a specific trailer could provide benefits, though.

“Pairing a SuperTruck trailer to an older model-year tractor would still result in miles per gallon (mpg) benefits, as would pairing a SuperTruck tractor to less aerodynamic trailers,” the executive summary of the report noted. “Benefits would be on a sliding scale, and fleet annual net mpgs would improve. Intentionally pairing by model type would provide the greatest opportunity for on-highway mpg gains, but this could only occur reliably where 100 percent of tractors and trailers were of the same configuration. In all other situations, benefits would vary based on a stochastic probability distribution of assets.”


The ability to pull off this type of matching system in the North American marketplace, though, is questionable due to the variables involved, and would require a complete rethinking of the way freight moves.

“While capital asset ratios like fleet tractor to trailer are important, load routing includes other market variables like time, pricing, load availability, asset location, driver availability and capability, etc.,” the report said.

“Intentional pairing would suggest a much higher number of trailers to tractors would be needed to position assets in all regions to permit reliable 100 percent pairing without long dwell times for drivers and tractors,” it added.

However, NACFE found that the growing number of GPS tracking systems and more data being generated by trailers does open a door, albeit slightly, for more efficient asset optimization in specific applications.

“The trailer and tractor configurations would need to be added to asset tracking,” the report said. “For example, the tracking data would not only know the tractor unit number and trailer unit number, but would have model information to know attributes; for example, whether the trailer or tractor are optimized for aerodynamics or optimized for weight, or whether the units are optimized for Midwest flat terrain, or extreme grades as in the Rocky Mountains.”

Roeth said the dynamics of the North American freight system just aren’t designed to benefit from intentional pairing of assets “except in very niche applications,” he said. “The whole freight system in North America is designed around keeping the tractors [and trailers] moving.”

Roeth noted that some applications, such as beverages, already operate in this manner as fleets pair “dramatically weight-reduced tractors with dramatically weight-reduced trailers to maximize payload.”

In the end, NACFE concluded that intentional pairing “is not realistic given the realities of today’s trucking industry.”


But new technology does offer opportunities through asset tracking and real-time asset management. With access to data such as driver information (including hours of service), tractor characteristics, trailer characteristics, asset status and location, loads, routes and weather, improved operational decisions can be made.

Combining this with vehicle data could allow fleets to match vehicles to certain situations. For example, lightweight tractors could be paired with lightweight trailers to maximize payload potential even if that trade-off resulted in a shorter lifespan for those assets. Tractors with down-sped transmissions could be utilized for specific routes where that technology can best benefit the fleet, as could high-power tractors for mountain routes, and highly aerodynamic vehicles on long-run highway routes.

“There is a notion that intentionally pairing tractors and trailers by model characteristics has the potential to benefit freight transport, but only in some specific circumstances,” the report said. “Intentional pairing would be a fundamental shift in the majority of current operations where drop and hook prevails. However, whether implicitly or explicitly, some level of intentional pairing is already done today, such as deciding if a trailer needs to be refrigerated or dry, or deciding if a 48-foot or 53-foot [trailer] is required, or if in a trailer yard, a particular empty trailer needs to be moved to another site to meet market demands.”

The report notes that further research on intentional pairing and its associated costs (hardware, software and operational changes) would need to be completed to develop a true total cost of ownership model. 

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