STAA doubles
STAA doubles or double pups are a type of long combination vehicle that makes up less than 3% of the freight trailer fleet in the US. They are named for the Surface Transportation Assistance Act (STAA) of 1982.[1] Each trailer is 28.5 feet (8.7 meters) long and 8.5 feet (2.6 meters) wide. The doubles are connected via a dolly. This long combination vehicle is the only combination of trailers allowed nationwide in America. The axle weight allowed is 20,000 pounds (9,100 kg) per single axle.