US Bridges

NH109 over Shannon Brook

Fair

Carroll County, New Hampshire · 3.3 MI from Tuftonboro Tl · Structure no. 017601860019300

Built
1929
96 years old, rebuilt 2015
Condition
Fair
inspected July 2024
Type
Slab
Concrete
Length
25 ft
1 main span
Daily traffic
2,514
2023 count
Owner
State
State Highway Agency

About this bridge

NH109 over Shannon Brook is a concrete slab carrying NH109 over Shannon Brook in Carroll County, New Hampshire. It was built in 1929 and reconstructed in 2015, so it is 96 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 2,514 vehicles a day, roughly 4% of them trucks, projected to reach 3,720 by 2043. The structure is 25 ft (7.6 m) long and 34 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesNH109
CrossesShannon Brook
Location3.3 MI from Tuftonboro Tl
RouteState Highway 109
CountyCarroll County
StateNew Hampshire
Coordinates43.73027, -71.35752
Functional classRural Major Collector

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 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 adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating75.8 US tons
Inventory rating45.4 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length25 ft (7.6 m)
Longest span23 ft (7 m)
Deck width34 ft (10.3 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,514 (2023)
Projected traffic3,720 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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 NH109 over Shannon Brook built?

It was built in 1929, making it 96 years old in 2025. It was reconstructed in 2015.

What condition is NH109 over Shannon 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 July 2024.

How much traffic does NH109 over Shannon Brook carry?

About 2,514 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is NH109 over Shannon Brook?

The structure is 25 ft (7.6 m) long with a longest span of 23 ft (7 m) and a deck 34 ft wide.

Who owns NH109 over Shannon Brook?

It is owned by the State Highway Agency.