US Bridges

I-93 SB over Old Nh 3B

Fair

Belknap County, New Hampshire · Tilton-Sanborton Tl · Structure no. 023101520003900

Built
1962
63 years old, rebuilt 1986
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
135 ft
3 main spans
Daily traffic
14,214
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 SB over Old Nh 3B is a steel stringer/multi-beam or girder carrying I-93 SB over Old Nh 3B in Belknap County, New Hampshire. It was built in 1962 and reconstructed in 1986, 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 14,214 vehicles a day, roughly 9% of them trucks, projected to reach 21,036 by 2043. The structure is 135 ft (41.1 m) long and 44 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesI-93 SB
CrossesOld Nh 3B
LocationTilton-Sanborton Tl
RouteInterstate 93
CountyBelknap County
StateNew Hampshire
Coordinates43.4793, -71.59011
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.9 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length135 ft (41.1 m)
Longest span53 ft (16.1 m)
Deck width44 ft (13.4 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,214 (2023)
Projected traffic21,036 by 2043
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed6.2 mi (10 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)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-93 SB over Old Nh 3B built?

It was built in 1962, making it 63 years old in 2025. It was reconstructed in 1986.

What condition is I-93 SB over Old Nh 3B 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 Old Nh 3B carry?

About 14,214 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-93 SB over Old Nh 3B?

The structure is 135 ft (41.1 m) long with a longest span of 53 ft (16.1 m) and a deck 44 ft wide.

Who owns I-93 SB over Old Nh 3B?

It is owned by the State Highway Agency.