Aug 18, 2019 · HS-20 is the truck live loadings of the AASHTO specification, where H stands for highway, S stands for semi-trailer, 20 stands for 20-ton weight of the tractor (first two axles). Each axle will carry the loads as follow, the first axle carries 8,000 pounds, the second axle, 14 feet away carries 32,000 pounds and a single-axle semitrailer 14-30