US Bridges

I-93 NB over Pemigewasset River

Fair

Grafton County, New Hampshire · 1.84 MI Thornton Tl · Structure no. 028402020006800

Built
1970
55 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
408 ft
3 main spans
Daily traffic
7,017
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 NB over Pemigewasset River is a steel continuous stringer/multi-beam or girder carrying I-93 NB over Pemigewasset River in Grafton County, New Hampshire. It was built in 1970, so it is 55 years old, younger 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 7,017 vehicles a day, roughly 9% of them trucks, projected to reach 10,385 by 2043. The structure is 408 ft (124.4 m) long and 45 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-93 NB
CrossesPemigewasset River
Location1.84 MI Thornton Tl
RouteInterstate 93
CountyGrafton County
StateNew Hampshire
Coordinates43.96018, -71.67909
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.4 US tons
Inventory rating35.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length408 ft (124.4 m)
Longest span155 ft (47.2 m)
Deck width45 ft (13.7 m)
Roadway width40 ft (12.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,017 (2023)
Projected traffic10,385 by 2043
Trucks9%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 NB over Pemigewasset River built?

It was built in 1970, making it 55 years old in 2025.

What condition is I-93 NB over Pemigewasset 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 July 2023.

How much traffic does I-93 NB over Pemigewasset River carry?

About 7,017 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I-93 NB over Pemigewasset River?

The structure is 408 ft (124.4 m) long with a longest span of 155 ft (47.2 m) and a deck 45 ft wide.

Who owns I-93 NB over Pemigewasset River?

It is owned by the State Highway Agency.