US Bridges

Lyman Road over Mill Brook

Good

Grafton County, New Hampshire · .59 MI N.W. Jct. 302 · Structure no. 015000900012100

Built
1974
51 years old
Condition
Good
inspected April 2024
Type
Frame
Concrete
Length
30 ft
1 main span
Daily traffic
708
2023 count
Owner
State
State Highway Agency

About this bridge

Lyman Road over Mill Brook is a concrete frame carrying Lyman Road over Mill Brook in Grafton County, New Hampshire. It was built in 1974, so it is 51 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 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 708 vehicles a day, roughly 10% of them trucks, projected to reach 1,047 by 2043. The structure is 30 ft (9.1 m) long and 32 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesLyman Road
CrossesMill Brook
Location.59 MI N.W. Jct. 302
RouteState Highway 0
CountyGrafton County
StateNew Hampshire
Coordinates44.24399, -71.88623
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 protection7 GoodSome minor problems.
Last inspectionApril 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 rating57.8 US tons
Inventory rating34.7 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length30 ft (9.1 m)
Longest span27 ft (8.2 m)
Deck width32 ft (9.9 m)
Roadway width29 ft (8.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic708 (2023)
Projected traffic1,047 by 2043
Trucks10%
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

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 Lyman Road over Mill Brook built?

It was built in 1974, making it 51 years old in 2025.

What condition is Lyman 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 April 2024.

How much traffic does Lyman Road over Mill Brook carry?

About 708 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Lyman Road over Mill Brook?

The structure is 30 ft (9.1 m) long with a longest span of 27 ft (8.2 m) and a deck 32 ft wide.

Who owns Lyman Road over Mill Brook?

It is owned by the State Highway Agency.