US Bridges

Plains Road over Mill Brook

Poor

Grafton County, New Hampshire · 1.0 MI from Lyman Tl · Structure no. 015000880012500

Built
1975
50 years old
Condition
Poor
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
27 ft
1 main span
Daily traffic
96
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Plains Road over Mill Brook is a steel stringer/multi-beam or girder carrying Plains Road over Mill Brook in Grafton County, New Hampshire. It was built in 1975, so it is 50 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 96 vehicles a day, projected to reach 142 by 2043. The structure is 27 ft (8.2 m) long and 22 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesPlains Road
CrossesMill Brook
Location1.0 MI from Lyman Tl
CountyGrafton County
StateNew Hampshire
Coordinates44.24467, -71.88828
Functional classRural Local

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 16 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
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 rating25.2 US tons
Inventory rating18 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length27 ft (8.2 m)
Longest span25 ft (7.6 m)
Deck width22 ft (6.7 m)
Roadway width21 ft (6.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic96 (2023)
Projected traffic142 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 Plains Road over Mill Brook built?

It was built in 1975, making it 50 years old in 2025.

What condition is Plains Road over Mill Brook in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in October 2024.

How much traffic does Plains Road over Mill Brook carry?

About 96 vehicles per day (2023 count).

How long is Plains Road over Mill Brook?

The structure is 27 ft (8.2 m) long with a longest span of 25 ft (7.6 m) and a deck 22 ft wide.

Who owns Plains Road over Mill Brook?

It is owned by the City or Municipal Highway Agency.