US Bridges

Nh 28 Bypass over Cohas Brook

Fair

Rockingham County, New Hampshire · 4.45 MI S Auburn Tl. · Structure no. 001300950004400

Built
1937
88 years old
Condition
Fair
inspected March 2023
Type
Slab
Concrete
Length
22 ft
1 main span
Daily traffic
5,769
2023 count
Owner
State
State Highway Agency

About this bridge

Nh 28 Bypass over Cohas Brook is a concrete slab carrying Nh 28 Bypass over Cohas Brook in Rockingham 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 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 5,769 vehicles a day, roughly 4% of them trucks, projected to reach 8,538 by 2043. The structure is 22 ft (6.7 m) long and 47 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesNh 28 Bypass
CrossesCohas Brook
Location4.45 MI S Auburn Tl.
RouteState Highway 28
CountyRockingham County
StateNew Hampshire
Coordinates42.9472, -71.35006
Functional classUrban Minor Arterial

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.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating30 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length22 ft (6.7 m)
Longest span20 ft (6.1 m)
Deck width47 ft (14.3 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,769 (2023)
Projected traffic8,538 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 28 Bypass over Cohas Brook built?

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

What condition is Nh 28 Bypass 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 March 2023.

How much traffic does Nh 28 Bypass over Cohas Brook carry?

About 5,769 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Nh 28 Bypass over Cohas Brook?

The structure is 22 ft (6.7 m) long with a longest span of 20 ft (6.1 m) and a deck 47 ft wide.

Who owns Nh 28 Bypass over Cohas Brook?

It is owned by the State Highway Agency.