US Bridges

Nh 12A over Mascoma River

Fair

Grafton County, New Hampshire · 2.7 Mi. N. Plainfield Tl · Structure no. 014400550010300

Built
1977
48 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
114 ft
1 main span
Daily traffic
12,844
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Nh 12A over Mascoma River is a steel stringer/multi-beam or girder carrying Nh 12A over Mascoma River in Grafton County, New Hampshire. It was built in 1977, so it is 48 years old, younger than the New Hampshire average of 56.9 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 12,844 vehicles a day, roughly 5% of them trucks, projected to reach 19,009 by 2043. The structure is 114 ft (34.7 m) long and 65 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesNh 12A
CrossesMascoma River
Location2.7 Mi. N. Plainfield Tl
RouteState Highway 12A
CountyGrafton County
StateNew Hampshire
Coordinates43.63399, -72.31738
Functional classUrban Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to 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 rating55.6 US tons
Inventory rating38.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length114 ft (34.7 m)
Longest span110 ft (33.5 m)
Deck width65 ft (19.7 m)
Roadway width52 ft (15.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,844 (2023)
Projected traffic19,009 by 2043
Trucks5%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal 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 Nh 12A over Mascoma River built?

It was built in 1977, making it 48 years old in 2025.

What condition is Nh 12A over Mascoma River in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in July 2024.

How much traffic does Nh 12A over Mascoma River carry?

About 12,844 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is Nh 12A over Mascoma River?

The structure is 114 ft (34.7 m) long with a longest span of 110 ft (33.5 m) and a deck 65 ft wide.

Who owns Nh 12A over Mascoma River?

It is owned by the City or Municipal Highway Agency.