US Bridges

Nh 12 over Mill Brook

Poor

Cheshire County, New Hampshire · 4.3 MI to Walpole Tl · Structure no. 027201590012500

Built
1941
84 years old
Condition
Poor
inspected November 2024
Type
Culvert
Concrete
Length
21 ft
1 main span
Daily traffic
6,478
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 12 over Mill Brook is a concrete culvert carrying Nh 12 over Mill Brook in Cheshire County, New Hampshire. It was built in 1941, so it is 84 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 6,478 vehicles a day, roughly 7% of them trucks, projected to reach 9,587 by 2043. The structure is 21 ft (6.5 m) long. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesNh 12
CrossesMill Brook
Location4.3 MI to Walpole Tl
RouteState Highway 12
CountyCheshire County
StateNew Hampshire
Coordinates42.99125, -72.39604
Functional classRural Minor Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Culvert4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionNovember 2024
Inspection intervalevery 8 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating99 US tons
Inventory rating22.5 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadH 15
Structure length21 ft (6.5 m)
Longest span21 ft (6.5 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,478 (2023)
Projected traffic9,587 by 2043
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 12 over Mill Brook built?

It was built in 1941, making it 84 years old in 2025.

What condition is Nh 12 over Mill Brook in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in November 2024.

How much traffic does Nh 12 over Mill Brook carry?

About 6,478 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is Nh 12 over Mill Brook?

The structure is 21 ft (6.5 m) long with a longest span of 21 ft (6.5 m).

Who owns Nh 12 over Mill Brook?

It is owned by the State Highway Agency.