Regulations for State roads in 16 States!

Regulations for State roads in 16 States! 1024 707 TruckScience

Earlier this year, we added truck size and weight regulations to our Axle Weight Calculator for Interstate roads in all US States.

Now we’ve started adding regulations for State roads… starting with California, Delaware, Idaho, Illinois, Iowa, Michigan, Minnesota, New Jersey, New York, Ohio, Oregon, Pennsylvania, Texas, Virginia, West Virginia and Wisconsin.

For us, this represents hours of trudging through heaps of documentation! For you, it means lots more options in the regulations library, and another step towards absolute peace of mind 😊

No rules of thumb

In some cases, restrictions on Interstate roads are more liberal than on State routes. In others, limits on the Interstate are more conservative than those on State roads. There really are no shortcuts! That’s where the TruckScience library of regulations comes in… You choose the states your truck will operate in, and whether on State or Interstate roads in those states, or indeed a combination of both, and the program works out the size and weight limits that will apply.

Non-compliance flagged in red!

The program automatically flags if your Federally-compliant combination is not compliant on the State roads in your chosen states, or vice versa.

Length restrictions on State roads

The US Federal Code of Regulations (23 CFR Part 658) prohibits states from restricting the overall length of truck tractor and semi-trailer combinations. However, off of the Interstate and National Network highways, individual states can – and do – restrict the overall length of these combinations.

There are often differences in other length restrictions too, for example Kingpin distance and Trailer length.

Let’s take an example…

Let’s look at a Freightliner Cascadia, with a 279” wheelbase and a 53’ trailer – a typical Over The Road truck combination. While it is legal on the Interstate and National Network, it is not compliant with length restrictions on State roads in Illinois, Minnesota, New Jersey and New York.

Freightliner Cascadia Length Restrictions

While the combination is illegal on State roads in all of the chosen states, the reasons for non-compliance vary from one state to another!

Freightliner Cascadia - Length Restrictions - Regulations

Legal here, not legal there!

Illinois and New York have an overall length restriction of 780” (65’).  Although Minnesota has a more liberal OA length restriction of 900” (75’), this rig, at 76 feet long, is not allowed on its State roads. It is the trailer length of 53’ which is causing a problem for New Jersey’s State roads, as there is a trailer length restriction of 48’ both there and in New York. Furthermore, there is a maximum ‘Kingpin to Rearmost Axle’ limitation of 42.5’ in Illinois, and that measurement for this configuration is 43 feet.

TruckScience - Axle Weight Calculator - Regulations for State roads

Federal Bridge Formula

Congress enacted the Bridge Formula in 1975, to limit the weight-to-length ratio of a vehicle crossing a bridge. Weight limits are determined by the number of axles as well as axle spacing.

Bridge Formula on State roads

Some states implement their own Bridge formulas on State roads.  In the case of these states, weight limits (for gross weights, axle weights, and groups of axle weights) differ to the restrictions that apply on federal roads, or the Federal Bridge formula. 

Higher weight limits on State roads in Idaho

Iowa is one state which has its own bridge formula for non-primary highways, which allows for higher weight limits.

Idaho is another state which permits straight trucks to be heavier on State roads than on Interstate highways.

Let’s take another example…

Let’s take a straightforward 6X4 straight truck as an example……

The maximum weight allowed on the rear axle group on Interstate roads in Idaho is 34,000lb, and the gross weight may be up to 54,000lb.

6X4 straight truck permissible weights

If you come off of the Interstate onto Idaho’s State roads however, the rear axle limit jumps to 37,800lb, while the gross weight limit goes up by over 20%, to 66,000lb.

6X4 straight truck permissible weights

From Idaho to Wyoming

Interestingly, the limit for a 6×4 tandem axle on an Interstate road in Wyoming is 36,000lb, which is higher than that for Interstate roads in Idaho, but lower than the limit for State roads in Idaho.

6X4 straight truck permissible weights

If a truck is to travel from the interstate in Wyoming on to State roads in Idaho, via the Idaho interstate, the lesser of all 3 of the limits above needs to be applied. The TruckScience Axle Weight Calculator takes care of all of this.

6X4 straight truck permissible weights regulations

We’ve chosen ‘Wyoming Interstate’, ‘Idaho Interstate’ and ‘Idaho State Roads’ from the pre-populated Regulations library. This works out the tandem limit to 34,000lb, which is Idaho’s Interstate limit, and the gross weight to 54,000lb, which is the Interstate limit for both Idaho and Wyoming.

6X4 straight truck permissible weights regulations

Some higher, some lower…

While some states legislate for higher weight limits on State roads, others implement lower weight limits on State roads than on the Interstate and Designated Roads.

Wisconsin’s bridge formula for State roads reduces the maximum weight for State routes to 60% of the Interstate weights, because a different bridge formula to the Federal bridge formula is applied.

6X4 straight truck permissible weights

In this example, the gross weight limit for a 6×4 straight truck drops from 54,300lb to 32,580lb when we choose ‘Wisconsin State Roads’ regulations, as opposed to ‘Wisconsin Interstate’. Note how weights for front and rear axles, and total weight are all dramatically reduced.

6X4 straight truck permissible weights

Interestingly, the 54,300lb gross limit for Wisconsin Interstate is slightly higher than the US Federal bridge formula, which would allow 54,000lb for this combination.

Some both higher and lower…

Michigan is an unusual case, in that travel on Interstate roads under State rules is allowed. This is because the State rules have been grandfathered into the Federal code.  Much higher gross weights can be achieved on both Interstate and State routes when traveling in Michigan.  However, although the rules for State roads allow for higher gross weights, axle weights are generally reduced.

6X4 straight truck permissible weights regulations

In this example, most axle weights have been reduced to 13,000lb, despite the more than 65,000lb gross weight allowance.

6X4 straight truck permissible weights

Coming Soon

Our team continue to monitor, study, digest and dissect the documentation for both interstate and State roads in all States. More regulations will be added to the Axle Weight Calculator in the coming months. Let us know if there’s a particular State you’d like to see added soon.

Further Reading

You will find detailed documentation, related to truck size and weight regulations for State roads, on the following websites:

Growing Library

Our team continues to add product specs as well as regulations to the TruckScience library. We’ve recently added vehicle specs for

  • Chevrolet Silverado 1500, 2500HD and 3500HD
  • DAF CF480 & CF530
  • Eicher Pro
  • FAW JH6
  • Ford Super Duty F-350, F-450, F-550 and F-600
  • Freightliner SD114, 114SD SFA and EconicSD
  • FUSO Canter and Fighter
  • GMC Sierra 3500HD
  • Hino 500 Series
  • Isuzu CYJ
  • Iveco S-Way
  • Kenworth K220, T359 and T800
  • Mack Granite and LR
  • Mazda BT-50
  • Mercedes-Benz Arocs and Econic & Commuter
  • RAM 5500
  • Scania G & P-Series
  • SinoTruk T5G
  • UD Trucks Quester & Croner
  • Volvo FMX and VNR
  • Western Star 4700 SB, 47X and 49X

And specs for these trailer, body, equipment and payload items:

  • Afrit trailers
  • Atlas cranes
  • CAT Telehandlers
  • FASSI cranes
  • Jost 5th Wheels,  combinations, and
  • THERMOKING T-90 and Precedent truck refrigeration units, and Heat King units

These were added at the request of TruckScience users in the United States, Canada, Australia, New Zealand, and South Africa. If there is something you would like to have added to our growing library of specs, just reach out and we will gladly add it for you.

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