SmartWay Transport | EPA420F10-053 | www.epa.gov/smartway | 734-214-4767 | smartway_transport@epa.gov

Longer Combination Vehicles

A Glance at Clean Freight Strategies

Energy

and 

Fuel Savings

1 Trucking firms should 

consider use of LCVs on 

routes where their use is 

allowed and appropriate. 

2 For more information on what types of 

vehicle configurations 

are allowed in each state, 

contact your state or 

federal department of 

transportation, or your 

state or national trucking 

Next Steps

association.

.

Increasing the cargo capacity of combination trucks by using longer or multiple 

trailers can save fuel and reduce greenhouse gas emissions by up to 34 metric 

tons per year.

What is the challenge?

The amount of cargo that a typical combination truck can carry is limited by its trailer capacity. 

A typical combination truck consists of a three-axle tractor pulling a two-axle, 53 foot trailer, 

with the capacity to carry approximately 3,800 cubic feet and 45,000 pounds of cargo. 

What is the solution?

Longer combination vehicles (LCVs) are combination trucks with multiple trailers and/or 

longer trailers than those used with a standard five-axle combination truck. Common configurations are:

• Rocky Mountain Double: One trailer up to 53 feet long and one trailer up to 28.5 feet 

long, with a combined weight of up to 120,000 pounds

• Turnpike Double: Two trailers, each up to 53 feet long with a combined weight of up to 

148,000 pounds

• Triple: Three trailers, each up to 28.5 feet long with a combined weight of up to 132,000 

pounds

• Eight-Axle Twin Trailer: Two trailers, each up to 33 feet long with a total of eight axles and 

a combined weight of up to 124,000 pounds

The extra capacity that LCVs provide enables truck fleets to haul the same amount of cargo 

with fewer trips. LCVs have slightly lower fuel economy, as measured in miles per gallon, 

than typical combination trucks. However, because LCVs carry more cargo per trip, they 

require less fuel to haul a ton of freight one mile. This measure of fuel economy is called a 

ton-mile. LCVs generally have much better ton-mile fuel economy than other combination 

trucks. Since only part of a truck’s fuel consumption is used to overcome mass, the percent 

increase in LCV ton-miles exceeds the percent increase in LCV fuel consumption. Increased 

productivity cuts fuel consumption and reduces greenhouse gas and air pollutant emissions. 

The environmental benefits could be slightly mitigated if LCV use rises at the expense of 

freight train use, since freight trains are generally more fuel-efficient and have lower emissions per ton-mile than freight trucks. 

Federal and state laws specify truck size and weight limits. A 1991 federal law prevents 

Gallons Saved 

= 

2166 gallons

Gallons Saved 

= 

3500 gallons

Fuel Cost Savings

= 

$8,233

Fuel Cost Savings

= 

$13,300 

Fuel Savings 

= 

13 %

Fuel Savings 

= 

21 %

Rocky Mountain Doubles

Turnpike Doubles & Triples
Longer Combination Vehicles

SmartWay Transport | EPA420F09-xxx | www.epa.gov/smartway | 734-214-4767 | smartway_transport@epa.gov

LCV expansion into states that did not permit these vehicles before the law’s passage. Longer combination vehicles 

currently operate in 16 states west of the Mississippi River and on turnpikes in 5 states east of the Mississippi River. 

Twenty-nine states do not allow LCVs. Of the states in which LCVs operate, 11 allow operation of triples, 8 allow 

triples with permits, and 8 allow Rocky Mountain Doubles. Three states allow operation of these LCVs without restrictions. 

Additional factors may influence the more widespread use of LCVs. LCVs have inherent stability and control limitations because of their length and number of trailers. Therefore, it is important that only experienced drivers under safe 

conditions operate LCVs. Widespread use of LCVs could have an adverse affect on bridges and other transportation 

infrastructure.

Savings and Benefits 

LCVs are more fuel-efficient, on a ton-mile basis, than typical combination trucks. For example, a Rocky Mountain 

Double consumes 13 percent less fuel per ton-mile of freight, compared to a typical combination truck. This saves 

over $8,000 in fuel costs per year. Turnpike Doubles and Triples reduce fuel use per ton-mile by 21 percent, saving 

over $13,000 in annual fuel costs.

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