NH 18
Carrying NH 18 over GALE RIVER
1.6 MI FROM SUGAR HILL TL, Grafton, New Hampshire
Data updated May 2026
FHWA NBI record, refreshed with each annual release.
Bridge Snapshot: NH 18
The NH 18 bridge in Grafton, New Hampshire carries NH 18 over GALE RIVER. It was built in 1930, making it 96 years old today. The structure is built primarily of steel and spans 1 section, stretching 17.7 meters (58 feet) end to end. Daily traffic averages 690 vehicles, placing it in the lower-traffic tier of New Hampshire bridges. It is owned and maintained by State Highway Agency.
The latest FHWA inspection records show a deck rating of 5/9, superstructure at 5/9, substructure at 5/9. The weakest component sits in fair condition. No reported major component scores in the Poor range under the current federal condition thresholds. Its NBI inventory load rating is 22.0 metric tons.
Sourced from the FHWA National Bridge Inventory. See our methodology for refresh cadence and NBI release vintage.
How NH 18 compares
Live comparison across New Hampshire.
Historical Sufficiency Rating
PlainBridge-computedFHWA discontinued this calculated item; it does not determine current condition, funding eligibility, posting, or closure. How the historical reference is calculated.
Condition Ratings
Full 0–9 scale + sufficiency-rating breakdown: how condition ratings work.
Structural Details
- Year Built
- 1930
- Material
- Steel
- Number of Spans
- 1
- Structure Length
- 17.7 m (58 ft)
- Deck Width
- 8.5 m (28 ft)
- Owner
- State Highway Agency
- Avg Daily Traffic
- 690 vehicles/day
- Structure Number
- 008700700011500
Location
Data Source
FHWA National Bridge Inventory (NBI).
FHWA NBI Program ↗Condition Analysis
- • The deck (driving surface) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
- • At 5/9, the superstructure (beams and supports above the deck) shows fair condition, with minor wear flagged for upkeep.
- • The substructure (piers and abutments) is in fair condition (5/9), with minor deterioration that may require routine maintenance.
How to read this record
This page shows what the last federal inspection recorded, not whether NH 18 is safe to cross today. Here is how to use it.
- NBI condition ratings reflect the latest record in this annual dataset, not a live status. Current routine inspection intervals are risk-based.
- Learn how the 0–9 condition scale and Good/Fair/Poor categories are defined. How condition ratings work
- Compare NH 18 against other structures in Grafton and across New Hampshire. New Hampshire bridges
- Noticed visible damage or a safety concern? Report it to the agency that owns the bridge, or call 911 in an emergency. How to report a bridge
Condition codes come straight from the FHWA National Bridge Inventory and are not a real-time safety judgment. Only the owning agency, a state DOT, county, or other owner, can post, restrict, or close a bridge.
Frequently Asked Questions
What do the condition ratings mean for NH 18?
NH 18 in Grafton, New Hampshire has a deck rating of 5/9, superstructure rating of 5/9, and substructure rating of 5/9 on the FHWA's 0–9 scale.
How often is NH 18 inspected?
NH 18's responsible agency sets its routine interval under FHWA's risk-based inspection rules; this page does not expose the scheduled interval. It carries about 690 vehicles per day.
What does “structurally deficient” mean in older bridge reports?
FHWA retired that reported status beginning with the 2018 archive. NH 18 is currently shown as Fair condition from its component ratings; that category is not a live closure or safety decision.
What is the inventory load rating for NH 18?
NH 18 has an NBI inventory load rating of 22.0 metric tons.
Who is responsible for maintaining NH 18?
NH 18 is owned and maintained by State Highway Agency.
How old is NH 18 and does age affect safety?
NH 18 was built in 1930, making it 96 years old.
Disclaimer: Bridge condition data is from the FHWA NBI and reflects the last reported inspection. A Poor condition rating is not a live declaration that a bridge is closed or unsafe for travel. For current closure, posting, or safety information, contact the responsible transportation agency.
Every figure on PlainBridge is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.