Structure 3600960003900 · Grafton County, NH

US 4 over Crystal Lake Brook

Carries US 4 over Crystal Lake Brook, 0.6 Mi From Enfield Tl.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructure8/9 · Very Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT76 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9 · sets the ratingSuperstructure 7/9 · sets the ratingSubstructure 8/9

76 ft end to end, longest span 26 ft. 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 slab bridge.

Built1941rebuilt 1993
Length76.1 ft23.2 m
Daily traffic7,633counted 2023
Last inspectedMay 2024every 24 months

Location

StateNew Hampshire
CountyGrafton
Location0.6 Mi From Enfield Tl
CarriesUS 4
CrossesCrystal Lake Brook
Coordinates43.64718, -72.10268

Physical Characteristics

MaterialConcrete Continuous
DesignSlab
Total Length76.1 ft (23.2 m)
Max Span25.9 ft (7.9 m)
Deck Width46.6 ft (14.2 m)
Deck Area329.4 sq m
Main Spans3
Year Built1941 (reconstructed 1993)

Traffic

Avg Daily Traffic7,633 (2023)
Truck Traffic7%
Lanes On Bridge2

Inspection & Ownership

Last InspectionMay 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number003600960003900

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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