US Bridges

Nh 11 over West Alton Brook

Fair

Belknap County, New Hampshire · 1.9 MI SE Gilford Tl · Structure no. 000600960028700

Built
1923
102 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
22 ft
1 main span
Daily traffic
5,130
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 11 over West Alton Brook is a steel stringer/multi-beam or girder carrying Nh 11 over West Alton Brook in Belknap County, New Hampshire. It was built in 1923, so it is 102 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 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 5,130 vehicles a day, roughly 7% of them trucks, projected to reach 7,592 by 2043. The structure is 22 ft (6.7 m) long and 36 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesNh 11
CrossesWest Alton Brook
Location1.9 MI SE Gilford Tl
RouteState Highway 11
CountyBelknap County
StateNew Hampshire
Coordinates43.54166, -71.30098
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating32.8 US tons
Inventory rating19.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length22 ft (6.7 m)
Longest span20 ft (6.1 m)
Deck width36 ft (10.9 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,130 (2023)
Projected traffic7,592 by 2043
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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 West Alton Brook built?

It was built in 1923, making it 102 years old in 2025.

What condition is Nh 11 over West Alton Brook 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 West Alton Brook carry?

About 5,130 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is Nh 11 over West Alton Brook?

The structure is 22 ft (6.7 m) long with a longest span of 20 ft (6.1 m) and a deck 36 ft wide.

Who owns Nh 11 over West Alton Brook?

It is owned by the State Highway Agency.