US Bridges

River Road over Grant Brook

Fair

Grafton County, New Hampshire · 2.6 MI FR Hanover Tl · Structure no. 015700560009900

Built
1978
47 years old
Condition
Fair
inspected August 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
37 ft
1 main span
Daily traffic
347
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

River Road over Grant Brook is a prestressed concrete box beam or girders - multiple carrying River Road over Grant Brook in Grafton County, New Hampshire. It was built in 1978, so it is 47 years old, younger 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 347 vehicles a day, roughly 4% of them trucks, projected to reach 513 by 2043. The structure is 37 ft (11.3 m) long and 16 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesRiver Road
CrossesGrant Brook
Location2.6 MI FR Hanover Tl
CountyGrafton County
StateNew Hampshire
Coordinates43.80215, -72.18285
Functional classRural Local

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.4 US tons
Inventory rating36 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length37 ft (11.3 m)
Longest span35 ft (10.7 m)
Deck width16 ft (4.9 m)
Roadway width16 ft (4.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic347 (2023)
Projected traffic513 by 2043
Trucks4%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal 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 River Road over Grant Brook built?

It was built in 1978, making it 47 years old in 2025.

What condition is River Road over Grant 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 August 2023.

How much traffic does River Road over Grant Brook carry?

About 347 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is River Road over Grant Brook?

The structure is 37 ft (11.3 m) long with a longest span of 35 ft (10.7 m) and a deck 16 ft wide.

Who owns River Road over Grant Brook?

It is owned by the City or Municipal Highway Agency.