Union Pacific is dedicated to providing secure and undamaged delivery of customers' shipments. To ensure this, they have implemented a process to help prevent damage to rail infrastructure that can be caused by shipping wagons that exceed the recommended maximum gross weight. The Union Pacific system is approved for heavy-axle wagons that can support up to 286,000 pounds of gross weight. However, at certain locations in the Union Pacific, the track structure (in most cases, bridges) is unable to properly handle and distribute this excess weight and may be restricted to 268,000 pounds or more depending on the length of the wagon.
Trains of this length are not always feasible to travel and, thus, the maximum limit on freight trains in North America is usually between 170 and 220 cars, that is, about 14,000 feet in total, with an average weight of around 14,000 tons or less. As the weight of each car increases, the total capacity of the train increases significantly before increasing the length of the trains, allowing the total tonnage of the train to be increased even more. Since the mid-19th century, engineers have been striving to move more cargo by train or ship by constructing ever larger machines as technology allowed. This has enabled them to raise the maximum weight for shipping a train without compromising safety.