US Bridges

NH120 over Great Brook

Good

Grafton County, New Hampshire · 2.2 MI from Plainfield Tl · Structure no. 014401500008400

Built
1944
81 years old, rebuilt 1993
Condition
Good
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
31 ft
1 main span
Daily traffic
2,671
2023 count
Owner
State
State Highway Agency

About this bridge

NH120 over Great Brook is a steel stringer/multi-beam or girder carrying NH120 over Great Brook in Grafton County, New Hampshire. It was built in 1944 and reconstructed in 1993, so it is 81 years old, older than the New Hampshire average of 56.9 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 2,671 vehicles a day, roughly 4% of them trucks, projected to reach 3,953 by 2043. The structure is 31 ft (9.4 m) long and 36 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesNH120
CrossesGreat Brook
Location2.2 MI from Plainfield Tl
RouteState Highway 120
CountyGrafton County
StateNew Hampshire
Coordinates43.61788, -72.22425
Functional classRural Major Collector

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating91.1 US tons
Inventory rating54 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length31 ft (9.4 m)
Longest span28 ft (8.5 m)
Deck width36 ft (10.9 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,671 (2023)
Projected traffic3,953 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 km)
TollOn a free road
National Highway SystemNo
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusPossibly eligible for the National Register; requires further investigation
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$314,000 (2025 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was NH120 over Great Brook built?

It was built in 1944, making it 81 years old in 2025. It was reconstructed in 1993.

What condition is NH120 over Great Brook in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in June 2023.

How much traffic does NH120 over Great Brook carry?

About 2,671 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is NH120 over Great Brook?

The structure is 31 ft (9.4 m) long with a longest span of 28 ft (8.5 m) and a deck 36 ft wide.

Who owns NH120 over Great Brook?

It is owned by the State Highway Agency.