US Bridges

Lower Ridge Road over Academy Brook

Fair

Merrimack County, New Hampshire · 1.6 MI FR Nh 106 · Structure no. 015501640012400

Built
1931
94 years old
Condition
Fair
inspected September 2023
Type
Arch - Deck
Concrete
Length
45 ft
1 main span
Daily traffic
533
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Lower Ridge Road over Academy Brook is a concrete arch - deck carrying Lower Ridge Road over Academy Brook in Merrimack County, New Hampshire. It was built in 1931, so it is 94 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 6 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 533 vehicles a day, roughly 4% of them trucks, projected to reach 788 by 2043. The structure is 45 ft (13.7 m) long and 24 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesLower Ridge Road
CrossesAcademy Brook
Location1.6 MI FR Nh 106
CountyMerrimack County
StateNew Hampshire
Coordinates43.35848, -71.44653
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating28 US tons
Inventory rating15 US tons

Structure

Structure typeArch - Deck
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length45 ft (13.7 m)
Longest span45 ft (13.7 m)
Deck width24 ft (7.3 m)
Roadway width21 ft (6.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic533 (2023)
Projected traffic788 by 2043
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 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 Lower Ridge Road over Academy Brook built?

It was built in 1931, making it 94 years old in 2025.

What condition is Lower Ridge Road over Academy 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 2023.

How much traffic does Lower Ridge Road over Academy Brook carry?

About 533 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Lower Ridge Road over Academy Brook?

The structure is 45 ft (13.7 m) long with a longest span of 45 ft (13.7 m) and a deck 24 ft wide.

Who owns Lower Ridge Road over Academy Brook?

It is owned by the City or Municipal Highway Agency.