Six-axle truck weight reform is bolstered by voluminous academic research and practical on-the-ground experience.

The following state, federal, international and academic sources have confirmed the safety and benefits of allowing trucks equipped with six axles to carry more freight:

  • American Transportation Research Institute
  • European Union
  • Organisation for Economic Co-operation & Development
  • Maine DOT
  • Minnesota DOT
  • National Academy of Sciences
  • United Kingdom Department for Transport
  • Univ. of Michigan Transportation Research Inst.
  • U.S. Department of Transportation
  • Vermont DOT
  • Wisconsin DOT

The individual studies available below represent a small portion of the recent truck weight research. For access to further research materials, please contact us.

U.S. DEPARTMENT OF TRANSPORTATION COMPREHENSIVE TRUCK SIZE & WEIGHT LIMITS STUDY TECHNICAL REPORTS

The findings of this 2015 U.S. DOT study confirm the safety and efficiency of heavier six-axle vehicles, demonstrating that 91,000-pound six-axle trucks are federal bridge formula compliant and stop one foot faster than the 80,000-pound five-axle truck currently used throughout the nation.

FEDERAL HIGHWAY ADMINISTRATION HIGHWAY STATISTICS 2013

The Federal Highway Administration’s statistics from 2013 show that truck miles traveled have increased 22 times faster than road capacity since federal truck weight limits were last increased in 1982.

DIRECTORY OF SIGNIFICANT TRUCK SIZE AND WEIGHT RESEARCH

This 2011 report by Jodi L. Carson, P.E., Ph.D. submitted to the National Cooperative Highway Research Program shows that reducing the number of trucks needed to deliver a specific amount of freight would help reduce vehicle miles traveled – and therefore help make roads safer.

ANALYSIS OF THE POTENTIAL BENEFITS OF LARGER TRUCKS FOR U.S. BUSINESSES OPERATING PRIVATE FLEETS

Based on this 2009 study by the University of Michigan Transportation Research Institute, six-axle trucks loaded to 91,000 pounds allow shippers to move a given amount of product with a median reduction in fuel consumption of 13 percent, relative to five-axle trucks carrying 80,000 pounds.

INTERNATIONAL VEHICLE PERFORMANCE BENCHMARKING STUDY

This 2008 study by the Organisation for Economic Co-operation & Development (OECD) outlines the vehicle weight limits set by nations around the world, establishing that Canada, Mexico, and most European countries already employ higher vehicle weight limits than the U.S. 

AASHTO Directory of Significant Truck Size and Weight Research

This 2011 document, requested by the American Association of State Highway and Transportation Officials, provides a comprehensive overview of existing truck size and weight research.

Engineering Analysis of Maine’s Interstate Bridges

Maine DOT conducted this engineering analysis after a recent one-year pilot project that allowed 100,000 pound, six-axle trucks on Maine’s interstate highways—concluding that the configuration is safe for the state’s bridge network.

Interstate & State Weight Limit Chart

As this chart demonstrates, 44 states already utilize higher truck weight limits on state roads and could improve highway safety by allowing safer, six-axle trucks on portions of their Interstate networks, which are by far the safest place for heavier traffic.

Impact and Analysis of Higher Vehicle Weight Limits on Minnesota’s Interstate System

This Minnesota DOT paper comments that, "An increase in vehicle weight limits would increase the allowable weight per trip, so fewer truck trips would be necessary to carry the same weight. Freight transportation cost savings due to increases in vehicle weight limits would benefit not only shippers and carriers but all consumers."

Interstate Highway Truck Limits - White Paper

This document prepared by the Maine DOT concludes that allowing six-axle, 100,000 pound trucks on the state’s Interstate System would increase traffic safety, improve the environment, increase business competitiveness, and reduce transportation infrastructure costs—at no cost to the taxpayer.

Transportation Research Board Truck Weight Study

The Transportation Research Board conducted a comprehensive study on truck weight reform, determining that "[o]pportunies exist for improving the efficiency of the highway system through reform of federal truck size and weight regulations."

Soy Transportation Coalition Study on Truck Weight Reform

A 2009 analysis of important elements of truck weight reform, prepared by a coalition of soybean growers.

Wisconsin Truck Size & Weight Study

Based on the findings of this 2009 Wisconsin DOT study, if 97,000-pound six-axle trucks had been allowed to travel on interstate highways in 2006, 90 truck-related accidents would have been prevented in the state during that year.

European Union Weight Study

This 2008 EU study discusses the “effects of adapting the rules on weights and dimensions of heavy commercial vehicles,” and demonstrates the benefits of allowing heavier trucks to transport goods.

Impact of the Truck Weight Increase in the United Kingdom

This 2007 analysis by the U.K. Department for Transport concludes fatal truck-related accident rates have declined by 35% since the country raised weight limits to 97,000 pounds for six-axle trucks in 2001. According to the department, more freight has been shipped, while the vehicle miles traveled to deliver a ton of freight has declined.

Energy and Emissions Impacts of Operating Higher Productivity Vehicles

The American Transportation Research Institute found that the 97,000-pound, six-axle truck configuration achieves 151 ton-miles per gallon, compared to 129 for the 80,000-pound, five-axle vehicle – a 17% improvement.