US Bridges

Isaac Frye Highway over Souhegan River

Fair

Hillsborough County, New Hampshire · .14 MI SE JCT 31 · Structure no. 027701100009600

Built
1993
32 years old
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
125 ft
1 main span
Daily traffic
851
2023 count
Owner
State
State Highway Agency

About this bridge

Isaac Frye Highway over Souhegan River is a steel stringer/multi-beam or girder carrying Isaac Frye Highway over Souhegan River in Hillsborough County, New Hampshire. It was built in 1993, so it is 32 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 851 vehicles a day, roughly 4% of them trucks, projected to reach 1,259 by 2043. The structure is 125 ft (38.1 m) long and 33 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesIsaac Frye Highway
CrossesSouhegan River
Location.14 MI SE JCT 31
RouteState Highway 0
CountyHillsborough County
StateNew Hampshire
Coordinates42.82185, -71.76039
Functional classUrban Local

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 protection8 Very GoodNo problems noted.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating75.2 US tons
Inventory rating45 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length125 ft (38.1 m)
Longest span118 ft (36 m)
Deck width33 ft (10.1 m)
Roadway width29 ft (8.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic851 (2023)
Projected traffic1,259 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemNo

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 Isaac Frye Highway over Souhegan River built?

It was built in 1993, making it 32 years old in 2025.

What condition is Isaac Frye Highway over Souhegan 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 April 2024.

How much traffic does Isaac Frye Highway over Souhegan River carry?

About 851 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Isaac Frye Highway over Souhegan River?

The structure is 125 ft (38.1 m) long with a longest span of 118 ft (36 m) and a deck 33 ft wide.

Who owns Isaac Frye Highway over Souhegan River?

It is owned by the State Highway Agency.