US Bridges

Bishop Road over Mill Brook

Fair

Grafton County, New Hampshire · 1.3 MI from Lyman Tl · Structure no. 015000900011800

Built
1970
55 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
24 ft
1 main span
Daily traffic
100
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Bishop Road over Mill Brook is a steel stringer/multi-beam or girder carrying Bishop Road over Mill Brook in Grafton County, New Hampshire. It was built in 1970, so it is 55 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 5 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 100 vehicles a day, roughly 4% of them trucks, projected to reach 148 by 2043. The structure is 24 ft (7.3 m) long and 21 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesBishop Road
CrossesMill Brook
Location1.3 MI from Lyman Tl
CountyGrafton County
StateNew Hampshire
Coordinates44.24323, -71.88433
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 length24 ft (7.3 m)
Longest span21 ft (6.4 m)
Deck width21 ft (6.4 m)
Roadway width19 ft (5.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2023)
Projected traffic148 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 Bishop Road over Mill Brook built?

It was built in 1970, making it 55 years old in 2025.

What condition is Bishop Road over Mill 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 September 2024.

How much traffic does Bishop Road over Mill Brook carry?

About 100 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Bishop Road over Mill Brook?

The structure is 24 ft (7.3 m) long with a longest span of 21 ft (6.4 m) and a deck 21 ft wide.

Who owns Bishop Road over Mill Brook?

It is owned by the City or Municipal Highway Agency.