US Bridges

Dorchester Road over Grant Brook

Good

Grafton County, New Hampshire · 1.3 MI from JCT RTE 10 · Structure no. 015701180009500

Built
1963
62 years old
Condition
Good
inspected March 2024
Type
Frame
Concrete
Length
25 ft
1 main span
Daily traffic
636
2023 count
Owner
State
State Highway Agency

About this bridge

Dorchester Road over Grant Brook is a concrete frame carrying Dorchester Road over Grant Brook in Grafton County, New Hampshire. It was built in 1963, so it is 62 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 636 vehicles a day, roughly 10% of them trucks, projected to reach 941 by 2043. The structure is 25 ft (7.6 m) long and 31 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesDorchester Road
CrossesGrant Brook
Location1.3 MI from JCT RTE 10
RouteState Highway 0
CountyGrafton County
StateNew Hampshire
Coordinates43.79903, -72.12179
Functional classRural Minor Collector

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 protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating52 US tons
Inventory rating31 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length25 ft (7.6 m)
Longest span22 ft (6.7 m)
Deck width31 ft (9.4 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic636 (2023)
Projected traffic941 by 2043
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 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 Dorchester Road over Grant Brook built?

It was built in 1963, making it 62 years old in 2025.

What condition is Dorchester Road over Grant 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 March 2024.

How much traffic does Dorchester Road over Grant Brook carry?

About 636 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Dorchester Road over Grant Brook?

The structure is 25 ft (7.6 m) long with a longest span of 22 ft (6.7 m) and a deck 31 ft wide.

Who owns Dorchester Road over Grant Brook?

It is owned by the State Highway Agency.