Flashback Fridays - Gross Vehicle Weights Evolve As Trucks Evolve

In its Flashback Friday series, FreightWaves publishes articles that look back at various aspects of the transportation industry's history. If there are topics that you think would be of interest, please send them to media@freightwaves.com

The early days…

Beginning around 1910, the concurrent development of a number of technologies gave rise to the modern trucking industry. With the advent of the gasoline-powered internal combustion engine, improvements in transmissions, the move away from chain drives to gear drives and the development of the tractor/semi-trailer combination, shipping by truck gained in popularity.

In 1913, the first state weight limits for trucks were introduced. At the time, only four states limited truck weights, from a low of 18,000 pounds (8,200 kilograms, or kg) in Maine to a high of 28,000 pounds (13,000 kg) in Massachusetts. The states enacted these laws to protect the roads (at that time roads were either dirt or gravel-surfaced) from damage caused by the iron and solid rubber wheels of early trucks. By 1914 there were almost 100,000 trucks on America's roads. However, solid tires, poor rural roads and a maximum speed of 15 miles per hour continued to limit the use of trucks to mainly urban areas.

Major improvements spurred by World War I

During World War I (1914-18) truck use and development was hastened by the increasing congestion on the nation's railroads, which carried increasing amounts of war materiel. As the nation's economy expanded, alternative modes of transportation were needed to move the additional freight. During the war, Roy Chapin (the founder of the Hudson Motor Company) served as chairman of the Highway Transport Committee of the Council of National Defense. Through the Committee's efforts, experiments with the first long-distance truck shipments were made. In addition, pneumatic (inflated) tires capable of supporting heavier loads were developed. The new tires also enabled trucks to drive at higher speeds. Two truck manufacturers also emerged in this period – White Motor Company and Mack Brothers Company (now Mack Trucks, Inc.). Over one million trucks were running on America's roadways by 1920 — a 10-fold increase in six years.

During the 1920s, several more advancements were made – rural roads were improved, the diesel engine was introduced (which was 25 to 40 percent more efficient than a gasoline-powered engine), truck and trailer sizes were standardized, and the "fifth wheel" coupling system was introduced, as were power-assisted brakes and steering.

Government oversight of trucking

As more trucks were used to move increasing amounts of freight, there was a corresponding increase in government oversight of the trucking industry. By 1933, all 48 states regulated the weight of trucks on their roads.

As noted in previous FreightWaves articles, the U.S. Congress created the Interstate Commerce Commission (ICC). The ICC was established to regulate the nation's railroads. But Congress also passed the Motor Carrier Act of 1935, which gave the ICC the authority to regulate the trucking industry.

While many of the ICC's actions negatively impacted trucking, it also got some things right. For example, in 1941, the ICC pointed out that inconsistent weight limitations imposed by the states had a negative impact on effective interstate truck commerce.

The birth of the Interstate Highway System

Also in 1941, President Franklin D. Roosevelt appointed a committee to consider the possibility of a "national inter-regional highway" system. However, the committee's progress was halted when the U.S. entered World War II after the bombing of Pearl Harbor.

The Federal-Aid Highway Act of 1944 authorized the designation of what are now known as interstate highways, but the legislation did not include funding to build the highways. Limited progress was made over the next 10 years, until President Dwight D. Eisenhower reignited interest in the interstate highway plan in 1954. As Supreme Commander of the Allies in Europe during World War II, Eisenhower knew first-hand that Germany had used its autobahns to move troops and war materiel effectively. Therefore, one of the reasons President Eisenhower advocated for an interstate system was that it would be available to help move the American military and its materiel more easily around the country in case of war. His call for a U.S. Interstate Highway System began a protracted and nasty debate among various transportation-related interests (such as the railroads, trucking companies, their associations, and related interest groups), over how the new highways would be paid for, where they would be located and what their impact would be.

Following two years of often acrimonious debate, the Federal-Aid Highway Act of 1956 authorized the construction of the Interstate Highway System. The system was envisioned as an interconnected network of controlled-access freeways. Among other uses, the interstates would allow larger trucks to travel at higher speeds through rural and urban areas.

Federal limits on trucks' gross vehicle weight

This legislation also authorized the first federal maximum gross vehicle weight (GVW) limits for trucks. The weight limit set in 1956 was 73,280 pounds (33,240 kg). The GVW limit was only for the interstate system, and a patchwork of state laws still governed state-maintained roadways.

Shortly after the birth of the interstate system, the American Association of State Highway and Transportation Officials (AASHTO) conducted extensive road and bridge tests in the late 1950s to determine how traffic contributed to the deterioration of pavement materials. AASHTO's tests led to a 1964 recommendation to Congress by the association that truck GVW limits should be determined by a "bridge formula" based on axle lengths, instead of a static upper limit.

By 1970 there were over 18 million trucks traveling on roads across the United States. While freight still moved by other transportation modes, trucking freight intrastate and interstate was the commonplace mode. The federal GVW was increased to 80,000 pounds (36,000 kilograms) by the Federal-Aid Highway Amendments of 1974. This legislation also began a system of a sliding scale of truck weight-to-length ratios based on the bridge formula, but did not establish a federal minimum weight limit. This lack of a minimum weight limit led six contiguous states in the Mississippi Valley (known as the "barrier states") to refuse to also increase their intrastate weight limits to 80,000 pounds. Therefore, the trucking industry was hampered by a barrier to efficient cross-country interstate commerce.

The problems caused by the barrier states went unsolved until after the trucking industry was deregulated in 1980. The Surface Transportation Assistance Act of 1982 established the needed federal minimum for truck weight limits. This Act standardized truck size and weight limits across the country for traffic on the Interstate Highway System.

Currently, federal limits are 80,000 pounds GVW, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group. Applications of the formula allow for up to seven axles and 86 feet or more length between axle sets, and a maximum load of 105,500 pounds.

Federal Highway Administration testimony

In July 2008, Jeffrey Paniata, who at the time was the Executive Director of the Federal Highway Administration (FHWA) testified at a joint hearing of the Subcommittee on Transportation and Infrastructure and the Subcommittee on Highways and Transit. Both subcommittees were part of the House of Representatives' Committee on Transportation and Infrastructure. The subcommittees were holding the hearing on truck weights and lengths to assess the impacts of existing laws and regulations.

While this testimony is more than 10 years old, many of the points Paniata made are still valid and relevant. He stated, "FHWA [which is an agency within the U.S. Department of Transportation] is responsible for monitoring and enforcing federal commercial motor vehicle size and weight limits – requirements that preserve the physical condition of the highway transportation system and the safety of its users.  Meeting the freight transportation needs of a growing economy in a safe and efficient manner is the challenge for all of us involved in this endeavor."

Although the maximum GVW for commercial motor vehicles on U.S. interstates was set at 80,000 pounds in 1975, several states interpreted their grandfathered permit authority broadly and allowed the operation of increasingly heavy trucks that came to be known as longer combination vehicles (LCVs). According to Paniata's testimony, "an LCV is any combination of a truck-tractor and two or more trailers or semi-trailers operating on the Interstate System with a GVW greater than 80,000 pounds." To counteract these varying state laws, Congress passed the Intermodal Surface Transportation Efficiency Act (ISTEA) in 1991, which froze the weight of LCVs on interstate highways. ISTEA also established limits on the length, width and configuration of longer double- and triple-trailer combinations on the "National Network" (NN).

The National Network and the importance of trucking

The NN is comprised of the interstate highways, U.S. highways and certain roadways designated by the states (generally, state-designated highways). This network is comprised of approximately 210,000 miles of roadway and includes the Interstate Highway System (about 47,000 miles) and certain other principal arterial roadways designated by the states and incorporated in federal regulation. Beyond the interstate system, the states may set their own weight limits. These limits (which can be lower or higher than federal limits) come into effect for intrastate commercial vehicle traffic not on the National Network.

Trucks are an integral part of the fabric of the U.S. (and global) economy. More than 70 percent of all the freight that moves in the U.S. moves by truck. Over the past 100 years, trucks have grown larger and heavier – and also "smarter" and safer thanks to technological innovations, which continue to be introduced. The companies that own or lease the trucks – and the men and women who drive the trucks – are more heavily regulated and scrutinized than at any time in history.

FreightWaves is proud to help tell the story of freight, and trucks and trucking are a major part of that story.  

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