US Bridges

I-93 NB over Cohas Brook

Good

Hillsborough County, New Hampshire · .4MI N Londonderry T.L. · Structure no. 016102000014300

Built
1962
63 years old, rebuilt 2017
Condition
Good
inspected April 2023
Type
Culvert
Concrete Continuous
Length
30 ft
2 main spans
Daily traffic
38,772
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 NB over Cohas Brook is a concrete continuous culvert carrying I-93 NB over Cohas Brook in Hillsborough County, New Hampshire. It was built in 1962 and reconstructed in 2017, 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 6% of them trucks, projected to reach 57,382 by 2043. The structure is 30 ft (9.1 m) long. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesI-93 NB
CrossesCohas Brook
Location.4MI N Londonderry T.L.
RouteInterstate 93
CountyHillsborough County
StateNew Hampshire
Coordinates42.94424, -71.38958
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
Channel and channel protection7 GoodSome minor problems.
Culvert7 GoodSome minor problems.
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
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating110.1 US tons
Inventory rating110.1 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadHS 20 + Mod
Structure length30 ft (9.1 m)
Longest span13 ft (4 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic38,772 (2023)
Projected traffic57,382 by 2043
Trucks6%
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 2017.

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 6% are trucks.

How long is I-93 NB over Cohas Brook?

The structure is 30 ft (9.1 m) long with a longest span of 13 ft (4 m).

Who owns I-93 NB over Cohas Brook?

It is owned by the State Highway Agency.