US Bridges

Bog Road over Patten Brook

Fair

Grafton County, New Hampshire · 0.5MI S Alexandria Ctr · Structure no. 000301740011600

Built
1950
75 years old, rebuilt 2014
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
30 ft
1 main span
Daily traffic
96
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

Bog Road over Patten Brook is a steel stringer/multi-beam or girder carrying Bog Road over Patten Brook in Grafton County, New Hampshire. It was built in 1950 and reconstructed in 2014, so it is 75 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 96 vehicles a day, roughly 4% of them trucks, projected to reach 142 by 2043. The structure is 30 ft (9.1 m) long and 16 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesBog Road
CrossesPatten Brook
Location0.5MI S Alexandria Ctr
CountyGrafton County
StateNew Hampshire
Coordinates43.60824, -71.79322
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
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry8: Equal to present desirable criteria
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating67 US tons
Inventory rating40.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans1
Design loadUnknown
Structure length30 ft (9.1 m)
Longest span26 ft (7.9 m)
Deck width16 ft (4.9 m)
Roadway width16 ft (4.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic96 (2023)
Projected traffic142 by 2043
Trucks4%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 Bog Road over Patten Brook built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 2014.

What condition is Bog Road over Patten 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 August 2023.

How much traffic does Bog Road over Patten Brook carry?

About 96 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Bog Road over Patten Brook?

The structure is 30 ft (9.1 m) long with a longest span of 26 ft (7.9 m) and a deck 16 ft wide.

Who owns Bog Road over Patten Brook?

It is owned by the City or Municipal Highway Agency.