US Bridges

Nh 12A over Mill Brook

Good

Sullivan County, New Hampshire · 2.8 MI from Claremont Tl · Structure no. 005500640009800

Built
1937
88 years old, rebuilt 1991
Condition
Good
inspected April 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
66 ft
1 main span
Daily traffic
2,087
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 12A over Mill Brook is a steel stringer/multi-beam or girder carrying Nh 12A over Mill Brook in Sullivan County, New Hampshire. It was built in 1937 and reconstructed in 1991, so it is 88 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 2,087 vehicles a day, roughly 7% of them trucks, projected to reach 3,088 by 2043. The structure is 66 ft (20.1 m) long and 35 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesNh 12A
CrossesMill Brook
Location2.8 MI from Claremont Tl
RouteState Highway 12A
CountySullivan County
StateNew Hampshire
Coordinates43.46823, -72.38411
Functional classRural Minor Arterial

Condition and inspection

Good

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2024
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 adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating61.9 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 15
Structure length66 ft (20.1 m)
Longest span57 ft (17.4 m)
Deck width35 ft (10.8 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,087 (2023)
Projected traffic3,088 by 2043
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemNo

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 Nh 12A over Mill Brook built?

It was built in 1937, making it 88 years old in 2025. It was reconstructed in 1991.

What condition is Nh 12A over Mill 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 April 2024.

How much traffic does Nh 12A over Mill Brook carry?

About 2,087 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is Nh 12A over Mill Brook?

The structure is 66 ft (20.1 m) long with a longest span of 57 ft (17.4 m) and a deck 35 ft wide.

Who owns Nh 12A over Mill Brook?

It is owned by the State Highway Agency.