It is said that the United States needs more power
Overloads of 400,000 pounds are routine and occasionally loads exceed 1,000,000 pounds. These are not only heavy but they are likewise very large. Trailers can exceed 20 feet in width, 15 feet in height and 20 feet in length. The term 'superloads' was coined to refer to these. Superload trucks are created to distribute the large loads both longitudinally and transversely. These trailers have progressed from standard hauling flatbeds to sophisticated self-propelled machines. The typical trailer type for superloads is a spreader-dolly trailer. These trailers distribute the load to individual subtrailer through spreader beams, resulting in a relatively even distribution of load on each individual axle.
On the other hand, the U.S Department of Transportation and highway Departments are trying to determine if the country's bridge infrastructure are able to support heavy and superload trucks by studying the building materials of the bridges. The high-strength/high performance steel bridges have microscopic flaws in both the steel itself and the welds of segments. In establishing the possible deterioration rate of the steel bridge these flaws are evaluated along with the load stress and load stress cycle. Steel bridges with high incidence of heavy truck traffic are more likely to crack and deteriorate at these discontinuities in the metal. The high-performance concrete bridges also referred to as reinforced concrete is used for both bridge decking and the entire bridge structures. Environmental conditions like freezing, thawing and ice-melt sale use have less of an effect on pothole development in high performance concrete decks than does the load stress and load stress cycle impact of heavy trucks carrying superloads.
When other materials are included for reinforcement, hairline cracks develop and it has been determined that these cracks grow and develop a grid-like pattern of fatigue with increase loads and load cycles. The timber bridges were built way before heavy trucks were utilized for freight or are built in areas where heavy truck traffic does not occur. The main design specification for the life expectancy of the bridge and safety is the weight. With regards to timber bridges, the weight capacity has to be posted and must be adhered to because exceeding posted weight causes material stress, deterioration and collapse. Because of this, the DOT is looking for alternative materials for bridge construction and analysis of the loads especially the superloads and over-dimensional loads carried by heavy trucks will be taken into consideration.