US Bridges

I-93 SB over Cohas Brook

Fair

Hillsborough County, New Hampshire · 1.5 MI E JCT Rt 28 · Structure no. 016101790012600

Built
1962
63 years old
Condition
Fair
inspected April 2023
Type
Culvert
Concrete Continuous
Length
40 ft
2 main spans
Daily traffic
26,271
2023 count
Owner
State
State Highway Agency

About this bridge

I-93 SB over Cohas Brook is a concrete continuous culvert carrying I-93 SB over Cohas Brook in Hillsborough County, New Hampshire. It was built in 1962, 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 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 26,271 vehicles a day, roughly 6% of them trucks, projected to reach 38,881 by 2043. The structure is 40 ft (12.3 m) long. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesI-93 SB
CrossesCohas Brook
Location1.5 MI E JCT Rt 28
RouteInterstate 93
CountyHillsborough County
StateNew Hampshire
Coordinates42.95861, -71.40901
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating110.1 US tons
Inventory rating71.7 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadHS 20 + Mod
Structure length40 ft (12.3 m)
Longest span19 ft (5.9 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26,271 (2023)
Projected traffic38,881 by 2043
Trucks6%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 SB over Cohas Brook built?

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

What condition is I-93 SB over Cohas Brook 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 2023.

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

About 26,271 vehicles per day (2023 count), of which roughly 6% are trucks.

How long is I-93 SB over Cohas Brook?

The structure is 40 ft (12.3 m) long with a longest span of 19 ft (5.9 m).

Who owns I-93 SB over Cohas Brook?

It is owned by the State Highway Agency.