US Bridges

NH123A over West Br Souhegan River

Fair

Hillsborough County, New Hampshire · 1.78 MI N Mass Sl · Structure no. 018601290006700

Built
1936
89 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
33 ft
1 main span
Daily traffic
1,299
2023 count
Owner
State
State Highway Agency

About this bridge

NH123A over West Br Souhegan River is a steel stringer/multi-beam or girder carrying NH123A over West Br Souhegan River in Hillsborough County, New Hampshire. It was built in 1936, so it is 89 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 1,299 vehicles a day, roughly 10% of them trucks, projected to reach 1,922 by 2043. The structure is 33 ft (10.1 m) long and 29 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesNH123A
CrossesWest Br Souhegan River
Location1.78 MI N Mass Sl
RouteState Highway 123A
CountyHillsborough County
StateNew Hampshire
Coordinates42.73141, -71.85439
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
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating69.7 US tons
Inventory rating41.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length33 ft (10.1 m)
Longest span28 ft (8.5 m)
Deck width29 ft (8.8 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,299 (2023)
Projected traffic1,922 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
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 NH123A over West Br Souhegan River built?

It was built in 1936, making it 89 years old in 2025.

What condition is NH123A over West Br 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 NH123A over West Br Souhegan River carry?

About 1,299 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is NH123A over West Br Souhegan River?

The structure is 33 ft (10.1 m) long with a longest span of 28 ft (8.5 m) and a deck 29 ft wide.

Who owns NH123A over West Br Souhegan River?

It is owned by the State Highway Agency.