Rail Versus Trucking: Who's The Greenest Freight Carrier?

Freight transport by rail photo

Our last two posts on improving trucking efficiency (see here and here) received quite a bit of push-back from the TreeHugger audience. While some comments were tempered, others were more blunt, "There is nothing green about trucks," you said. And, "Get freight back on the rails where it belongs."

At RMI we agree that any serious freight strategy needs to have a big picture, integrative perspective that includes smart land-use and development as well as efficient rail, truck, and shipping transport.Compared to trucking, rail transit does sport higher efficiency numbers - today's average train has an efficiency of 400 ton-miles per gallon whereas trucks currently hover around 130 ton-miles per gallon. Still, there are numerous reasons why addressing truck efficiency remains important, if not critical. For example, peer-reviewed research and companies like Wal-Mart have proved that trucks can easily achieve 260 ton-miles per gallon. And reaching 300+ ton-miles per gallon is not much harder, especially when a truck carries two or three trailers.

Maximizing the efficiency of all systems and using each mode for the strengths it possesses is the real key to efficient freight transport. So while we should expand rail infrastructure and increase its utilization, the near-term opportunity to drastically increase truck efficiency cannot be ignored.

Some other freight efficiency considerations:
Downstream Efficiency
As usual, the biggest lever for efficiency occurs downstream at the user end. In 2005, an average of 68 tons of goods moved 15,310 miles in the United States for each U.S. citizen. And that’s only for the goods shipped to, from, and within the nation. If we demand less goods, we'd also reduce the energy associated in manufacturing and transporting them across the country.

Rail Limitations
Both rail and trucking require significant infrastructure upgrades before they can efficiently move America's goods. While personal rail mobility has recently been marked for billions of dollars, the rail transport infrastructure continues to decline.

The main downside to rail is the lack of timely transport, a near non-starter for companies that demand just-in-time logistics. Further, as Don Baldwin from Michelin Tires noted at RMI's recent Trucking Summit, "the need to put things in storage makes rail particularly difficult for perishables." Perhaps this is why 43.8 percent of rail transit is comprised of coal while only 7.8 percent comes from farm products. This, from the Association of American Railroads.

Perhaps most importantly, trucks don't require their own infrastructure, and are therefore capable of reaching any destination without advance notice.

State-of-the-art Trucks Approach Rail's Efficiency Numbers
State-of-the-art trucks can begin to approach the ton-miles per gallon of trains (350+ ton-miles for trucks vs. 400 to 450 ton-miles for rail).

RMI's 2008 peer-reviewed analysis, based on tested science, found a combination of improved aerodynamics, low rolling resisitance tires, and more efficient engines could more than double the ton-mileage of the average class 8 truck from 130 ton-mile per gallon to 275 ton-mile/gallon.

Specifically, according to RMI analyst Mike Simpson, "Wind tunnel testing of a Prevost H5-60 articulated bus demonstrates a drag coefficient 50 percent smaller than that of a typical class 8 truck while maintaining similar cargo volume and exemplifying gap seals required for such streamlining. As aerodynamic drag composes roughly two-thirds of the fuel consumption for a tractor-trailer at highway speeds, a 50 percent reduction in drag represents a 33 percent reduction in fuel consumption. If you add in low rolling resistance tires (which save an additional 10 percent of fuel), and maximize the cargo volume while using lightweight materials for the structure, the total power required by the engine to maintain performance drops by almost 50 percent. At this point, a smaller, more efficient engine can pull the increased cargo load at a lower cost and almost double the ton-miles/gallon."

Adding an additional trailer could further stretch the efficiency of carrying freight to 335 ton-mile/gallon. (Of course long combination vehicles (LCVs) do have their limitations, but RMI's paper documents possible mitigation strategies.)

But 335 ton-miles/gallon still leaves a lot of efficiency on the table. For example, the accessory and auxiliary loads in a class 8 truck can account for 10 percent of its total power consumption. Simple measures like electrified compressors and advanced HVAC design can greatly reduce this demand. Also, advanced powertrains, like hybrid-electric and hybrid-hydraulic systems, can further reduce fuel consumption during acceleration while increasing the lifetime of brakes.

Intermodal Solutions
Ultimately, it may prove futile to pit one mode of transport against the other, especially when integrative solutions--like the classic J.B. Hunt case--can reap the benefits from both.

In 1989 J.B. Hunt signed a deal with Burlington Northern Santa Fe Railway Company, whereby a Hunt trailer could be directly loaded onto a railcar. In the beginning, 150 trailers and five railcars moved freight between Chicago and California, in 2008, more than 700,000 shipments were made.

J.B. Hunt's strategic partnership not only decreased emissions, but has provided the company with its largest source of operating revenue since 2003, when it first surpassed the trucking division. In 2007, Intermodal represented 47 percent of J.B. Hunt's total revenue and accounted for 65 percent of its net income.

The American Association of Railroads estimates that if an additional 10 percent of truck volume were shifted to intermodal, the annual savings would top 1 billion gallons of fuel.

What will contribute to more inter-modal growth? Infrastructure expansions and diesel prices. With rail efficiency, the cost-effectiveness of a transcontinental haul is obvious, but when diesel gets expensive, benefits apply to short hauls as well.

New Trucking and Freight Initiatives
Interestingly enough, of the two major initiatives that came out of RMI's Transformational Trucking Charrette, one focuses on developing a national freight strategy (to include trucks, rail, and more). The other initiative aims to create a U.S. Green Truck Council, modeled off of the U.S. Green Building Council.

In the end, a successful freight strategy needs to consider the efficiencies of all modes of transit. In the meantime though, when it is profitable and technologically possible to double trucking efficiency, why not save 3.8 billion gallons of diesel a year or more?

By: Rocky Mountain Institute, Maria Stamas

More posts on trucking.
With Diesel at $4 a Gallon, Truckers Are Slowing Down
Hybrid Truck Unveiled by Kenworth
Con-Way Limit Speed on Trucks to Conserve Fuel

Rail Versus Trucking: Who's The Greenest Freight Carrier?
Our last two posts on improving trucking efficiency (see here and here) received quite a bit of push-back from the TreeHugger audience. While some comments were tempered, others were more blunt, "There is nothing green about trucks," you said. And,

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