US Bridges

Nh 11 over Mad River

Fair

Strafford County, New Hampshire · 1.7 MI New Durham Tl · Structure no. 008400800012500

Built
1955
70 years old
Condition
Fair
inspected May 2024
Type
Tee Beam
Concrete
Length
38 ft
1 main span
Daily traffic
12,121
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 11 over Mad River is a concrete tee beam carrying Nh 11 over Mad River in Strafford County, New Hampshire. It was built in 1955, so it is 70 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 fair condition with a lowest component rating of 6 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 12,121 vehicles a day, roughly 7% of them trucks, projected to reach 17,939 by 2043. The structure is 38 ft (11.6 m) long and 43 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesNh 11
CrossesMad River
Location1.7 MI New Durham Tl
RouteState Highway 11
CountyStrafford County
StateNew Hampshire
Coordinates43.38691, -71.08172
Functional classRural 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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 24 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
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating30.8 US tons
Inventory rating18.5 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length38 ft (11.6 m)
Longest span35 ft (10.7 m)
Deck width43 ft (13.2 m)
Roadway width40 ft (12.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,121 (2023)
Projected traffic17,939 by 2043
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 11 over Mad River built?

It was built in 1955, making it 70 years old in 2025.

What condition is Nh 11 over Mad 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 May 2024.

How much traffic does Nh 11 over Mad River carry?

About 12,121 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is Nh 11 over Mad River?

The structure is 38 ft (11.6 m) long with a longest span of 35 ft (10.7 m) and a deck 43 ft wide.

Who owns Nh 11 over Mad River?

It is owned by the State Highway Agency.