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Axle Folly

In 1984, the blockbuster comedy Beverly Hills Cop starring Eddie Murphy was released. Murphy played the character Axel Foley, a Detroit cop investigating crimes in Beverly Hills. In truck world, we have axles (not axels) and follies (not Foley’s) when it comes to understanding the maximum number of axles certain trucks can have in Illinois. The article this week will dispel a common myth heard by truckers and cops alike…and it has nothing to do with bananas in a tailpipe.

To understand the maximum number of axles allowed on trucks and trailers in Illinois, one must first understand the Federal Bridge Formula (FBF). The FBF is a tiered system of increasing gross weights based on an increasing number of axles.

Pretend there is a bog of quicksand up ahead. Step in it with your boot, and you will sink. That is because all your weight is concentrated in a small area. The way to defeat the quicksand is to throw a sheet of plywood over it. Then when you step on it, your weight is distributed over a greater distance, reducing the opportunity for a slow, painful death.

A loose analogy? Yes, but the principle is sound. When it comes to truck weight law, the axles serve as the plywood distributing the weight over the road, or quicksand. The greater the number of axles spread over the greater distance, the less stress is placed upon the road surface causing less damage.

Illinois adopted the FBF in 1986 on a host of highways, primarily the Tollway and interstates. Other larger state highways which received federal funding were also included. Over time, more and more roads were considered “designated” by both the Illinois Department of Transportation and local units of government.

In 2010, all highways in Illinois became “designated” in regards to weight, meaning the FBF applied everywhere. Not surprising, Illinois was the last state in the Union to allow these weights.

No matter how many axles a truck has, gross weight can never exceed 80,000 pounds. That is the limit in Illinois. The FBF is technically a never-ending formula, and some states allow truck weights to exceed the Illinois limits of the FBF.

Here’s where truckers get confused, and unfortunately sometimes this line of thinking is fed by misinformed enforcement agents.

There is no law limiting the number of physical axles a truck may have in Illinois. None. This is a free country, and you are welcome in Illinois with as many axles as you want. There is no crime, no statute or citation that says after a certain number of axles, you are forbidden from crossing the border into the sovereign State of Illinois.

For instance, in the sovereign State of Wisconsin, it is not uncommon to see 5-axle straight trucks. These vehicles usually have a configuration consisting of a steer axle, two tag axles in the middle, then two fixed drive axles. The same trucks are seen in Illinois, but are missing the two tag axles in the middle. It’s also not uncommon to see 5-axle cement mixers in Wisconsin, but only 4-axle mixers in Illinois.

Does this mean those 5-axle straight trucks in Wisconsin are illegal in Illinois? Absolutely not! As long as they pay their fair share in fuel tax and registration, they are more than welcome to travel across the Land of Lincoln. However, those trucks which may receive credit for five axles under the FBF in Wisconsin are only given credit for four axles in Illinois. In other words, the same truck will receive less weight in Illinois as oppose to it’s northerly neighbor.

Let’s say a 5-axle straight truck comes into Illinois from Wisconsin and has a wheelbase of 21’. Under the FBF, the maximum gross weight is 61,000 pounds. In Illinois though, the law says to use the same 21’ measurement, but only gives credit for four axles, yielding a maximum gross weight of 56,000 pounds.

The number of axles isn’t what is illegal, there is just a limitation on the FBF. While straight trucks (single vehicles) are only allowed four axles under the FBF, combinations of vehicles (truck and trailer) are only given credit for six axles. You do not need a permit for extra axles, unless of course, the vehicle is overweight and non-divisible.

So bring them extra axles trucks into Illinois! Just remember that after a certain number, those extra axles are dead weight reducing the actual load which can be carried.

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