US Bridges

Turnpike Road over Mill Brook

Good

Grafton County, New Hampshire · 1.32 Mi. RTE 4 · Structure no. 009901620010600

Built
1985
40 years old
Condition
Good
inspected August 2023
Type
Frame
Concrete
Length
40 ft
1 main span
Daily traffic
143
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Turnpike Road over Mill Brook is a concrete frame carrying Turnpike Road over Mill Brook in Grafton County, New Hampshire. It was built in 1985, so it is 40 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 good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 143 vehicles a day, roughly 4% of them trucks, projected to reach 211 by 2043. The structure is 40 ft (12.2 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesTurnpike Road
CrossesMill Brook
Location1.32 Mi. RTE 4
CountyGrafton County
StateNew Hampshire
Coordinates43.58057, -71.93945
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54 US tons
Inventory rating36 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length40 ft (12.2 m)
Longest span35 ft (10.7 m)
Deck width26 ft (7.8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic143 (2023)
Projected traffic211 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal 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 Turnpike Road over Mill Brook built?

It was built in 1985, making it 40 years old in 2025.

What condition is Turnpike Road over Mill 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 August 2023.

How much traffic does Turnpike Road over Mill Brook carry?

About 143 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Turnpike Road over Mill Brook?

The structure is 40 ft (12.2 m) long with a longest span of 35 ft (10.7 m) and a deck 26 ft wide.

Who owns Turnpike Road over Mill Brook?

It is owned by the City or Municipal Highway Agency.