US Bridges

NH175 over Pemigewasset River

Fair

Grafton County, New Hampshire · 0.5 MI East JCT US 3 · Structure no. 028401970008500

Built
1976
49 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
280 ft
3 main spans
Daily traffic
682
2023 count
Owner
State
State Highway Agency

About this bridge

NH175 over Pemigewasset River is a steel continuous stringer/multi-beam or girder carrying NH175 over Pemigewasset River in Grafton County, New Hampshire. It was built in 1976, so it is 49 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 682 vehicles a day, roughly 10% of them trucks, projected to reach 1,009 by 2043. The structure is 280 ft (85.3 m) long and 34 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesNH175
CrossesPemigewasset River
Location0.5 MI East JCT US 3
RouteState Highway 175
CountyGrafton County
StateNew Hampshire
Coordinates43.97528, -71.67946
Functional classRural Minor 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
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 evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating51.1 US tons
Inventory rating30.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length280 ft (85.3 m)
Longest span105 ft (32 m)
Deck width34 ft (10.5 m)
Roadway width31 ft (9.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic682 (2023)
Projected traffic1,009 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 NH175 over Pemigewasset River built?

It was built in 1976, making it 49 years old in 2025.

What condition is NH175 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 May 2024.

How much traffic does NH175 over Pemigewasset River carry?

About 682 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is NH175 over Pemigewasset River?

The structure is 280 ft (85.3 m) long with a longest span of 105 ft (32 m) and a deck 34 ft wide.

Who owns NH175 over Pemigewasset River?

It is owned by the State Highway Agency.