Determining The Proper Trailer Length When Hauling Heavy Equipment

Posted on: 23 October 2015

Contractors don't always have a lot of experience hauling heavy equipment on the crossroads of America. This is why they often ask the question, "What's the longest trailer I can use?" The answer is: "It depends." Unfortunately, that answer isn't very clear, but it's a common response for many questions that involve sizes and weights. This is because the states in this country have their own rules and regulations when it comes to trailer length limits, in addition to federal size and weight limits. The answer also depends upon what type of vehicle is pulling the trailer, the number of trailing units, the kingpin to rear axle length, and even what route you are driving. With all of these variables, it can be a bit confusing to arrive at the right answer for you. Keep reading this article to learn about federal size and weight limits and the most confusing variable – the kingpin to rear axle length.

Federal Size & Weight Limits

Federal size and weight limits are determined by the Federal Highway Administration, or FHWA for short. Specifically, federal size and weight limits are included in the Code of Federal Regulations (CFR), Title 23, Part 658. The purpose for this part of the CFR is to follow the provisions set forth by the Surface Transportation Assistance Act of 1982. This section also prescribes national policies that govern truck size and weight. Every state must allow the federal government to set maximums on highways, regardless of what the state's laws are.

Federal Minimum Length

Thanks to the Transportation Assistance Act of 1982, all 48-foot semitrailers are allowed to drive on any portion of the National Network of highways, as long as it's being pulled by a truck-tractor. This provision includes lowboys, step-trailers, and flatbeds. A 48-foot trailer will meet the needs of most contractors who haul heavy equipment. But if you need something bigger, like a 53-foot trailer, the rules become more complex.

The Act grandfathered any trailers or semitrailers that were currently in use and were within each state's standard of length. When the Act was first introduced, this was a problem because only about half of the United States allowed a 53-foot trailer to travel on the highway. The other states had minimums that were less than 53 feet. Thankfully, over the years, those states updated their laws to allow 53-foot trailers, that is, every state except for Hawaii.

Here's where the kicker comes in. Some states that originally had a 48-foot maximum trailer length added a kingpin to rear axle distance limit for any trailer over 48 feet in length. The reason is to allow these states to regulate this distance in order to help control the turning radius and wheelbase of the trailer and the vehicle pulling it.

How To Measure Kingpin To Rear Axle

If your trailer has a single rear axle, start at the kingpin and measure the length to the center of the rear axle. If you have a group of rear axles, then measure from the center of the kingpin to the center of the group of axles. In case you are not sure, a kingpin is the round steel shaft that's attached to the front of a fifth wheel trailer. It's considered to be a coupling apparatus.

States With Kingpin To Rear Axle Length Limits

There are quite a few states and 1 city that have kingpin to rear axle length limits on their highways, and these limits will dictate how long of a trailer you can use to transport heavy equipment. These states are:

  1. Alabama

  2. California

  3. Connecticut

  4. Florida

  5. Illinois

  6. Indiana

  7. Maine

  8. Maryland

  9. Michigan

  10. Minnesota

  11. New Hampshire

  12. New Jersey

  13. New York

  14. New York City

  15. North Carolina

  16. Pennsylvania

  17. Rhode Island

  18. South Carolina

  19. Tennessee

  20. Vermont

  21. Virginia

  22. West Virginia

  23. Wisconsin

The trailer length limits for these states vary greatly. Check with your local highway department to find out what the limits are in your state. If your state isn't listed here, then there is a 53-foot length limit.

You now have all the information you need to determine what size trailer you can use when hauling heavy equipment to job sites, including a bit of information on who sets these laws. If you have any questions on trailer length limits, contact your local highway department. They will be happy to help you. You can also consider hiring an equipment hauling service, such as Santa Fe Tow Service.