Double & Triple Trailers
The use of double or triple trailers (often called longer combination vehicles) can allow for more payload to be moved per gallon of fuel consumed.
Given the dramatic improvement in aerodynamic drag and lower rolling resistance of tires, today’s tractors have plenty of power to pull the resulting heavier and longer loads. A dolly and appropriate electrical and air equipment are required to attach one trailer to another.
Double or triple trailers can be dropped at a location and picked up by a different tractor, improving logistics flexibility but requiring more management of the trailers and the dollies required to pull the second trailer. In addition, they cannot be used nationwide, since only some states permit their use.