US Bridges

I-93 NB over Cohas Brook

Good

Hillsborough County, New Hampshire · 1.6MI E JCT Rt 28 · Structure no. 016101870013400

Built
1962
63 years old, rebuilt 2021
Condition
Good
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
153 ft
3 main spans
Daily traffic
38,772
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 NB over Cohas Brook is a steel continuous stringer/multi-beam or girder carrying I-93 NB over Cohas Brook in Hillsborough County, New Hampshire. It was built in 1962 and reconstructed in 2021, so it is 63 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 good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 38,772 vehicles a day, roughly 11% of them trucks, projected to reach 57,382 by 2043. The structure is 153 ft (46.6 m) long and 90 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesI-93 NB
CrossesCohas Brook
Location1.6MI E JCT Rt 28
RouteInterstate 93
CountyHillsborough County
StateNew Hampshire
Coordinates42.95373, -71.40226
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating79 US tons
Inventory rating47.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length153 ft (46.6 m)
Longest span56 ft (17.1 m)
Deck width90 ft (27.4 m)
Roadway width83 ft (25.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic38,772 (2023)
Projected traffic57,382 by 2043
Trucks11%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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 Cohas Brook built?

It was built in 1962, making it 63 years old in 2025. It was reconstructed in 2021.

What condition is I-93 NB over Cohas Brook in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in April 2023.

How much traffic does I-93 NB over Cohas Brook carry?

About 38,772 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is I-93 NB over Cohas Brook?

The structure is 153 ft (46.6 m) long with a longest span of 56 ft (17.1 m) and a deck 90 ft wide.

Who owns I-93 NB over Cohas Brook?

It is owned by the State Highway Agency.