US Bridges

NH110 over Mill Brook

Fair

Coos County, New Hampshire · 3.8 MI Northumberland Tl · Structure no. 024001200009000

Built
1963
62 years old
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
68 ft
1 main span
Daily traffic
1,942
2023 count
Owner
State
State Highway Agency

About this bridge

NH110 over Mill Brook is a steel stringer/multi-beam or girder carrying NH110 over Mill Brook in Coos 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 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 1,942 vehicles a day, roughly 4% of them trucks, projected to reach 2,874 by 2043. The structure is 68 ft (20.7 m) long and 35 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesNH110
CrossesMill Brook
Location3.8 MI Northumberland Tl
RouteState Highway 110
CountyCoos County
StateNew Hampshire
Coordinates44.59704, -71.41137
Functional classRural Minor Arterial

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 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 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 rating45.9 US tons
Inventory rating27.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length68 ft (20.7 m)
Longest span64 ft (19.5 m)
Deck width35 ft (10.7 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,942 (2023)
Projected traffic2,874 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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 NH110 over Mill Brook built?

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

What condition is NH110 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 April 2024.

How much traffic does NH110 over Mill Brook carry?

About 1,942 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is NH110 over Mill Brook?

The structure is 68 ft (20.7 m) long with a longest span of 64 ft (19.5 m) and a deck 35 ft wide.

Who owns NH110 over Mill Brook?

It is owned by the State Highway Agency.