US Bridges

Mountain Road over Blackwater River

Good

Merrimack County, New Hampshire · Town RD 0.94 MI Andover · Structure no. 022900950013500

Built
2010
15 years old
Condition
Good
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
109 ft
1 main span
Daily traffic
96
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Mountain Road over Blackwater River is a steel stringer/multi-beam or girder carrying Mountain Road over Blackwater River in Merrimack County, New Hampshire. It was built in 2010, so it is 15 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 96 vehicles a day, projected to reach 142 by 2043. The structure is 109 ft (33.2 m) long and 27 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesMountain Road
CrossesBlackwater River
LocationTown RD 0.94 MI Andover
CountyMerrimack County
StateNew Hampshire
Coordinates43.4016, -71.79042
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable 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 alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating93.3 US tons
Inventory rating55.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length109 ft (33.2 m)
Longest span103 ft (31.4 m)
Deck width27 ft (8.2 m)
Roadway width23 ft (7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic96 (2023)
Projected traffic142 by 2043
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusEligible for the National Register of Historic Places
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 Blackwater River built?

It was built in 2010, making it 15 years old in 2025.

What condition is Mountain Road over Blackwater River 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 October 2024.

How much traffic does Mountain Road over Blackwater River carry?

About 96 vehicles per day (2023 count).

How long is Mountain Road over Blackwater River?

The structure is 109 ft (33.2 m) long with a longest span of 103 ft (31.4 m) and a deck 27 ft wide.

Who owns Mountain Road over Blackwater River?

It is owned by the City or Municipal Highway Agency.