New Hampshire commercial vehicle weight limits follow the federal Interstate standard of 80,000 lbs gross, 22,400 lbs per single axle, and 36,000 lbs per tandem axle group. The federal bridge formula (23 U.S.C. 127) applies on all routes. New Hampshire imposes spring weight restrictions on secondary roads and state routes typically March through May during the frost thaw cycle. Frost law postings are strictly enforced — violations carry substantial fines. Roads may reduce legal weights by 30–50% or close entirely to heavy vehicles. Check NHDOT for current restricted routes and posting dates. Oversize and overweight permits are available from NH DOT for loads exceeding standard limits. Verify current road-specific postings with the New Hampshire DOT before routing heavy loads.
New Hampshire imposes spring weight restrictions on secondary roads and state routes typically March through May during the frost thaw cycle. Frost law postings are strictly enforced — violations carry substantial fines. Roads may reduce legal weights by 30–50% or close entirely to heavy vehicles. Check NHDOT for current restricted routes and posting dates.
Check current restrictions at NH DOT →The federal bridge formula limits the weight on any group of axles based on the distance between the outermost axles in the group. It applies in New Hampshire on all routes where federal standards apply.
W = maximum weight in lbs · L = axle spacing in feet · N = number of axles
New Hampshire oversize/overweight permits issued by NHDOT at dot.nh.gov/administrator/permits.htm. Single-trip permits for most oversize/overweight loads. Annual permits for qualifying routine operations. Superload permits require engineering review. Spring frost law restrictions overlay all permits — loads legal under a permit may still be prohibited during active frost law posting. Always check NH road posting status before dispatching.
Apply for New Hampshire OS/OW Permit →On New Hampshire Interstate highways and state routes, the maximum gross vehicle weight is 80,000 lbs. However, NH allows 22,400 lbs on a single axle and 36,000 lbs on a tandem axle on state routes — both above the federal standard. These higher axle limits allow heavier legal payloads within the 80,000 lb GVW cap.
Yes. New Hampshire enforces strict spring frost law weight restrictions on secondary roads and state routes typically March through May. Restricted roads may reduce legal vehicle weight by 30–50% or prohibit heavy vehicles entirely. Violations carry substantial fines. Check NHDOT's frost law posting map at dot.nh.gov before routing off Interstate highways during spring.
New Hampshire oversize/overweight permits are issued by NHDOT at dot.nh.gov/administrator/permits.htm. Apply for single-trip or annual permits as appropriate. Note that spring frost law restrictions can prohibit permit moves on restricted roads — check current road posting status before dispatching. Superload permits require engineering review.
New Hampshire allows 22,400 lbs on a single axle and 36,000 lbs on a tandem axle — 2,400 and 2,000 lbs above federal limits respectively. This applies on New Hampshire state routes (not Interstate highways, which remain at federal limits). The higher limits benefit construction, aggregate, and timber operations in the state.
Port of New Hampshire (Portsmouth) handles import and export cargo along the Piscataqua River. Freight moves from the port via I-95 and NH-1 into the broader New England market. Portsmouth is a relatively small port compared to Boston, but it handles breakbulk, project cargo, and some container traffic. Drivers working port drayage here should be familiar with NH Route 1 weight postings and bridge restrictions near the waterfront.
Find flatbed trucks, lowboys, and heavy-haul equipment from dealers in New Hampshire.
Disclaimer
The information on this page is compiled from publicly available government sources and is provided for general informational purposes only. TruckRadar is an independent search engine — we are not affiliated with any government agency and this content does not constitute legal or compliance advice. Regulations change frequently; always verify current requirements directly with the official source before making compliance decisions.
Official source: New Hampshire NH Department of TransportationLast reviewed: 2026-04