US Bridges

I-93 SB over Salmon Brook

Fair

Belknap County, New Hampshire · 3.3MI F. Tilton T.L. · Structure no. 023101240009600

Built
1962
63 years old
Condition
Fair
inspected July 2024
Type
Culvert
Concrete
Length
28 ft
1 main span
Daily traffic
14,217
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 SB over Salmon Brook is a concrete culvert carrying I-93 SB over Salmon Brook in Belknap County, New Hampshire. It was built in 1962, so it is 63 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 14,217 vehicles a day, roughly 9% of them trucks, projected to reach 21,041 by 2043. The structure is 28 ft (8.5 m) long. If it were closed, the detour would be 14.3 mi (23 km).

Location

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CarriesI-93 SB
CrossesSalmon Brook
Location3.3MI F. Tilton T.L.
RouteInterstate 93
CountyBelknap County
StateNew Hampshire
Coordinates43.51947, -71.61702
Functional classRural Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
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
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating99 US tons
Inventory rating92 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20 + Mod
Structure length28 ft (8.5 m)
Longest span25 ft (7.6 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,217 (2023)
Projected traffic21,041 by 2043
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.3 mi (23 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
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 I-93 SB over Salmon Brook built?

It was built in 1962, making it 63 years old in 2025.

What condition is I-93 SB over Salmon 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 I-93 SB over Salmon Brook carry?

About 14,217 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-93 SB over Salmon Brook?

The structure is 28 ft (8.5 m) long with a longest span of 25 ft (7.6 m).

Who owns I-93 SB over Salmon Brook?

It is owned by the State Highway Agency.