Structure 15700840010500 · Grafton County, NH

Market Street over Grant Brook

Carries Market Street over Grant Brook, 4.0 Mi Fr Hanover Tl.

Overall conditionFair

Set by its lowest-rated component: Substructure at 5 of 9.

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating5/9 · Fair
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT28 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 5/9 · sets the rating

28 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.

Built197452 years old
Length27.9 ft8.5 m
Daily traffic72counted 2023
Last inspectedAugust 2023every 24 months

Location

StateNew Hampshire
CountyGrafton
Location4.0 Mi Fr Hanover Tl
CarriesMarket Street
CrossesGrant Brook
Coordinates43.80653, -72.15272

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length27.9 ft (8.5 m)
Max Span24.0 ft (7.3 m)
Deck Width24.3 ft (7.4 m)
Deck Area62.9 sq m
Main Spans1
Year Built1974

Traffic

Avg Daily Traffic72 (2023)
Truck Traffic4%
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number015700840010500

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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