US Bridges

Mountain Road over Andrew Brook

Fair

Merrimack County, New Hampshire · 1.25 Mi. Rte. 103 · Structure no. 018000900007400

Built
1936
89 years old
Condition
Fair
inspected September 2024
Type
Frame
Concrete
Length
35 ft
1 main span
Daily traffic
330
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Mountain Road over Andrew Brook is a concrete frame carrying Mountain Road over Andrew Brook in Merrimack County, New Hampshire. It was built in 1936, so it is 89 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 330 vehicles a day, roughly 4% of them trucks, projected to reach 488 by 2043. The structure is 35 ft (10.7 m) long and 21 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesMountain Road
CrossesAndrew Brook
Location1.25 Mi. Rte. 103
CountyMerrimack County
StateNew Hampshire
Coordinates43.29764, -72.03817
Functional classRural Minor Collector

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.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating56 US tons
Inventory rating25.2 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length35 ft (10.7 m)
Longest span30 ft (9.1 m)
Deck width21 ft (6.3 m)
Roadway width19 ft (5.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic330 (2023)
Projected traffic488 by 2043
Trucks4%
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 Mountain Road over Andrew Brook built?

It was built in 1936, making it 89 years old in 2025.

What condition is Mountain Road over Andrew 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 Mountain Road over Andrew Brook carry?

About 330 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Mountain Road over Andrew Brook?

The structure is 35 ft (10.7 m) long with a longest span of 30 ft (9.1 m) and a deck 21 ft wide.

Who owns Mountain Road over Andrew Brook?

It is owned by the City or Municipal Highway Agency.