Structure 5100430003600 · Coos County, NH

US 3 over Lyman Brook

Carries US 3 over Lyman Brook, 0.7 Mi NE Stratford Tl.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
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
CAR · 15 FT52 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 6/9 · sets the rating

52 ft end to end. Lengths and the car 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.

Built195274 years old
Length51.8 ft15.8 m
Daily traffic3,145counted 2023
Last inspectedJuly 2023every 24 months

Location

StateNew Hampshire
CountyCoos
Location0.7 Mi NE Stratford Tl
CarriesUS 3
CrossesLyman Brook
Coordinates44.77917, -71.58331

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length51.8 ft (15.8 m)
Max Span44.9 ft (13.7 m)
Deck Width35.1 ft (10.7 m)
Deck Area169.1 sq m
Main Spans1
Year Built1952

Traffic

Avg Daily Traffic3,145 (2023)
Truck Traffic7%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJuly 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number005100430003600

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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