US Bridges

US 3 over Bog Brook

Poor

Grafton County, New Hampshire · 1.2 MI from Plymouth Tl · Structure no. 003501080005800

Built
1929
96 years old
Condition
Poor
inspected November 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
40 ft
1 main span
Daily traffic
1,193
2023 count
Owner
State
State Highway Agency

About this bridge

US 3 over Bog Brook is a steel stringer/multi-beam or girder carrying US 3 over Bog Brook in Grafton County, New Hampshire. It was built in 1929, so it is 96 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 1,193 vehicles a day, roughly 4% of them trucks, projected to reach 1,765 by 2043. The structure is 40 ft (12.2 m) long and 28 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesUS 3
CrossesBog Brook
Location1.2 MI from Plymouth Tl
RouteU.S. Route 3
CountyGrafton County
StateNew Hampshire
Coordinates43.79822, -71.67386
Functional classRural Major Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2024
Inspection intervalevery 8 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54 US tons
Inventory rating32.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length40 ft (12.2 m)
Longest span34 ft (10.4 m)
Deck width28 ft (8.5 m)
Roadway width25 ft (7.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,193 (2023)
Projected traffic1,765 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

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 US 3 over Bog Brook built?

It was built in 1929, making it 96 years old in 2025.

What condition is US 3 over Bog Brook in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in November 2024.

How much traffic does US 3 over Bog Brook carry?

About 1,193 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is US 3 over Bog Brook?

The structure is 40 ft (12.2 m) long with a longest span of 34 ft (10.4 m) and a deck 28 ft wide.

Who owns US 3 over Bog Brook?

It is owned by the State Highway Agency.