Maine 100,000 lb Interstate Weight Exemption

The 100,000 lb Exemption Explained

Maine allows 100,000 lbs gross vehicle weight on all Interstate highways with a 6-axle or greater configuration. No special permit is needed. This is not a loophole, a workaround, or a temporary program — it is congressionally authorized under 23 USC Section 127(a)(11) as part of federal law.

For heavy haulers, this is one of the most significant weight advantages in the eastern United States. Instead of splitting a 100,000 lb load into two trips at the federal 80,000 lb cap, you make one trip. The fuel savings, time savings, and reduced wear on equipment are substantial.

What Qualifies

Axle Configuration

The minimum qualifying configuration is a 3-axle tractor pulling a tri-axle semitrailer (6 axles total). The 6-axle minimum is not negotiable — 5-axle combinations are limited to the standard 80,000 lb cap.

Which Roads

The exemption applies to ALL Interstate highways in Maine:

The exemption also applies to General Law Highways (state routes), though secondary road conditions and bridge restrictions may limit practical application.

Axle Weight Limits Still Apply

The gross weight exemption does not override individual axle limits. Federal bridge formula and these maximums still apply:

Distribute your 100,000 lbs across the axles properly. An overloaded single axle on a 6-axle combination is still a violation, even if gross weight is under 100,000 lbs.

Above 100,000 lbs: Special Permits

For loads exceeding 100,000 lbs, Maine issues special permits for weights up to 130,000 lbs and beyond with proper axle configurations and route approval.

Special permit loads require route approval because bridge weight limits may restrict certain crossings. Contact MaineDOT for permit applications.

Maine vs Vermont: Side-by-Side Comparison

Maine and Vermont are the only two states with Interstate weight exemptions above the 80,000 lb federal standard. The programs are similar but not identical.

The practical difference is 1,000 lbs — negligible for most loads. The key operational difference is that Vermont’s exemption applies only to non-tolled Interstates, while Maine’s applies to all Interstates including the tolled Maine Turnpike.

For carriers running heavy loads through both states, the Vermont 99,000 lb weight exemption guide covers VT-specific details.

Spring Frost Laws

Maine’s spring frost laws (March through May) reduce weight limits by 10-25% on secondary and posted roads during the thaw season. This can create a practical problem for 100,000 lb loads:

• Interstate highways are NOT subject to frost law reductions — the 100K exemption remains in effect
• Secondary roads TO and FROM the Interstate may be posted at reduced weights
• A delivery requiring secondary road access during frost season may need load splitting

:::tip Plan spring deliveries carefully. Your 100,000 lb load is legal on I-95 year-round, but the last 5 miles on a secondary road to the delivery site may be posted at 75% of normal weight during March-May frost restrictions. :::

Winter Frozen Ground Bonus

On the other end of the seasonal spectrum, Maine allows an additional ~10% weight tolerance for bulk commodities when the ground is frozen. This winter bonus effectively extends the weight advantage even further for qualifying carriers hauling bulk materials during the coldest months.

Insurance Implications

Running 100,000 lbs changes your risk profile. Heavier loads mean longer stopping distances, higher kinetic energy in collisions, and more severe outcomes. Maine pairs the heaviest Interstate weight exemption in the East with the highest state insurance minimums: $50,000/$100,000/$25,000 for BI/PD.

At $1,000,000 CSL, your coverage matches the payload. At state minimums, a single accident at 100,000 lbs could exhaust your coverage. RMS recommends $1,000,000 CSL or higher for carriers regularly operating at the 100K exemption weight.

Practical Considerations

Tire and Axle Wear

6-axle configurations distribute weight across more contact points, but the total load is still 25% above federal standard. Tire inspection, axle maintenance, and brake checks matter more at 100K.

Bridge Weight Limits

Not every bridge on General Law Highways can handle 100,000 lbs. Interstate bridges are engineered for the exemption, but when you exit the Interstate, verify bridge postings on your route.

Weigh Stations

Maine State Police Troop K operates weigh stations with WIM (weigh-in-motion) sensors. Trucks at 100K are not flagged for being overweight on Interstates, but axle weight distribution will be checked. Make sure individual axle limits are within spec.

For winter operations in Maine, including fuel planning for northern runs and frost law details, see the winter guide.