Most trucking companies that are familiar with hauling steel are also acquainted with oversize or over-dimensional loads. When one ships structural steel, length is usually the primary dimension at issue that creates requirements for special trailers and permits.
The maximum length for any item being shipped before specialized equipment and permit fees are required is 52′. Beyond this length, permits are always required, and beyond certain lengths a “stretch trailer” will be needed. Extending the length of the trailer will be the only adjustment necessary when transporting straight structural steel because the material will be self-supporting.
However, this dynamic will change once the steel has been curved, and a radius has been put in the material. Depending on the radius and arc length, the space required for the rolled steel will grow and can cause it to be wider than the legal limit. Curving steel also changes the center of gravity of the rolled steel, and the weight will shift to the top of the arc. And this weight shift can limit the number of pieces that can be stacked on top of each other to avoid tilting the trailer.
This balancing dynamic also becomes more problematic when the dimensions increase beyond the maximum legal or non-permitted size of 52′ in length and 102″ in width. The challenges of building a safe and balanced load can be met with blocking and creative, skillful arranging of the different sizes and shapes during the loading process.
The picture below shows a truck that is loaded with 35,682lbs. of curved structural steel. The load is both over-length and over-width but not over-weight. (The weight limit on a regular flatbed is 42,000lbs; on an aluminum trailer it is 46,000lbs.)
The biggest beam in this load is 58′ long x 11′-10″ wide. This beam alone would create an over-dimensional load. But 16 other tubes and beams were carefully nested to fit on the trailer in a balanced way. The curved structural steel members are destined to become the framework for a new high school near Atlanta Georgia.