Structure 3901470005800 · Coos County, NH

US 3 over Ammonoosuc River

Carries US 3 over Ammonoosuc River, 1.9 Mi Bethlehem Tl.

Overall conditionFair

Set by its lowest-rated component: Substructure at 6 of 9.

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT165 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

165 ft end to end, longest span 79 ft: about 2 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.

Built1972rebuilt 2003
Length165.0 ft50.3 m
Daily traffic5,178counted 2023
Last inspectedJuly 2023every 24 months

Location

StateNew Hampshire
CountyCoos
Location1.9 Mi Bethlehem Tl
CarriesUS 3
CrossesAmmonoosuc River
Coordinates44.27005, -71.54043

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length165.0 ft (50.3 m)
Max Span79.4 ft (24.2 m)
Deck Width57.7 ft (17.6 m)
Deck Area885.3 sq m
Main Spans2
Year Built1972 (reconstructed 2003)

Traffic

Avg Daily Traffic5,178 (2023)
Truck Traffic10%
Lanes On Bridge3

Inspection & Ownership

Last InspectionJuly 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical3 — Scour critical
Structure Number003901470005800

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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