US Bridges

Nh 45 over Souhegan River

Fair

Hillsborough County, New Hampshire · 3.21 Mi. N.Of Mason Tl · Structure no. 010400710010100

Built
1937
88 years old
Condition
Fair
inspected May 2024
Type
Frame
Concrete
Length
56 ft
1 main span
Daily traffic
2,721
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 45 over Souhegan River is a concrete frame carrying Nh 45 over Souhegan River in Hillsborough County, New Hampshire. It was built in 1937, so it is 88 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 5 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 2,721 vehicles a day, roughly 10% of them trucks, projected to reach 4,027 by 2043. The structure is 56 ft (17.1 m) long and 36 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesNh 45
CrossesSouhegan River
Location3.21 Mi. N.Of Mason Tl
RouteState Highway 45
CountyHillsborough County
StateNew Hampshire
Coordinates42.76714, -71.81194
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating89.1 US tons
Inventory rating40.3 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length56 ft (17.1 m)
Longest span47 ft (14.3 m)
Deck width36 ft (11 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,721 (2023)
Projected traffic4,027 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed6.2 mi (10 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 Nh 45 over Souhegan River built?

It was built in 1937, making it 88 years old in 2025.

What condition is Nh 45 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 May 2024.

How much traffic does Nh 45 over Souhegan River carry?

About 2,721 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Nh 45 over Souhegan River?

The structure is 56 ft (17.1 m) long with a longest span of 47 ft (14.3 m) and a deck 36 ft wide.

Who owns Nh 45 over Souhegan River?

It is owned by the State Highway Agency.