OS/OW permits application planning
Confirm the current New Hampshire Department of Transportation application process, then submit the exact loaded dimensions, axle weights and spacings, origin, destination, requested dates and proposed route.
New Hampshire Escort & Travel Regulations
New Hampshire Oversize and Overweight Permits: Legal Limits, Permit Rules and Route Planning
When is a New Hampshire oversize or overweight permit required?
New Hampshire requires an oversize or overweight permit when a vehicle or nondivisible load exceeds the legal limits that apply to its configuration and route. Applications are coordinated with New Hampshire Department of Transportation through OS/OW permits. Federal Interstate baselines are not blanket state authorization; axle spacing, bridges, route ownership and current permit conditions must be evaluated before movement.
New Hampshire Legal Limits and Permit Decision Points
Legal limits, routine permit envelopes and superload thresholds are different concepts. Use the complete loaded configuration, axle data, proposed route and current restrictions instead of treating one number as universal authorization.
| Parameter | Legal reference | Permit decision | Escalation | Official basis |
|---|---|---|---|---|
| Width | Federal National Network baseline: 8 ft 6 in (102 in); state statutes and route-specific exceptions remain controlling | Use New Hampshire Department of Transportation rules to determine whether the complete loaded width requires a New Hampshire permit. | The issued route can add escort, lane-control, time-of-day or local-jurisdiction conditions. | FHWA federal size overview and current state permit authority |
| Gross and axle weight | Federal Interstate baseline: 80,000 lb gross, 20,000 lb single axle and 34,000 lb tandem, subject to the Federal Bridge Formula | Submit actual axle weights, axle spacing, gross weight and load divisibility; state and route rules may be more restrictive. | Bridge analysis, additional axles or project-specific engineering may be required for higher weights. | FHWA federal weight limits and Bridge Formula |
| Height and length | No single federal height limit applies nationwide; state law, vehicle configuration and network rules control height and length | Confirm New Hampshire legal limits and route clearances using the current New Hampshire Department of Transportation instructions. | Overhead clearance, turning geometry, overhang and local-road ownership can change the authorized route. | FHWA size-and-weight overview and state permit instructions |
| Permit jurisdiction | A state permit is not automatic authorization for every locally controlled road or private facility | Identify the owner of every state, county, municipal, toll, bridge, port, terminal and final-mile segment. | Separate local, police, utility, port, bridge or facility coordination may be required. | FHWA state permit contacts and issuing-authority conditions |
New Hampshire Permit Operations and Jurisdiction Responsibilities
Route and structure review
A permit does not override posted bridges, closures, construction, overhead conflicts or unsafe conditions. Recheck the authorized route immediately before dispatch.
Travel windows and escorts
Use the issued New Hampshire permit for the controlling travel hours, holiday restrictions, escort conditions, signs, flags, lighting and any police or utility coordination.
First- and final-mile authority
Resolve county, municipal, toll, port, terminal and private-property responsibility before dispatch. State authorization should never be represented as blanket local permission.
New Hampshire Department of Transportation
Permit system: OS/OW permits | Phone: 603-271-2691
New Hampshire Municipal Permit and Access Guides
Start with the state guide, then identify municipal, county, bridge, toll, port, terminal and facility authority for the actual first- and final-mile route.
New Hampshire Heavy Haul Permit FAQs
Who issues New Hampshire oversize and overweight permits?
New Hampshire Department of Transportation is the statewide permit authority identified for this guide. The listed application system is OS/OW permits, and the permit-office phone is 603-271-2691. Confirm current contact and submission instructions before applying.
Does New Hampshire use the federal 80,000-pound limit for every road and vehicle?
No. The 80,000-pound figure is a federal Interstate gross-weight baseline for qualifying combinations. Axle limits, spacing, bridge formula, state law, roadway class, posted structures and configuration-specific exceptions still control.
Does a New Hampshire state permit cover city and county roads?
Do not assume blanket local coverage. Municipal streets, county roads, toll facilities, bridges, ports, terminals and private property may require separate authorization or coordination.
What information is needed before ordering a New Hampshire permit?
Verify loaded length, width, height, gross weight, axle weights and spacings, load divisibility, origin, destination, proposed route, travel dates, equipment condition and first- and final-mile access.
Official New Hampshire sources and review status
Reviewed 2026-08-04. Recheck the issued permit, current notices, bridge postings, weather, route restrictions and local permissions before movement.
Review the New Hampshire load and route before ordering
Share the complete configuration, axle data, addresses, requested dates and proposed route so every jurisdiction and restriction can be identified.