Structure 9901610013500 · Grafton County, NH

Millbrook Road over Mill Brook

Carries Millbrook Road over Mill Brook, 0.9mi. Orange Tl.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructure8/9 · Very Good
Channelnot part of overall4/9 · Poor
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT42 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 6/9 · sets the ratingSubstructure 8/9

42 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.

Built200521 years old
Length41.7 ft12.7 m
Daily traffic96counted 2023
Last inspectedAugust 2023every 24 months

Location

StateNew Hampshire
CountyGrafton
Location0.9mi. Orange Tl
CarriesMillbrook Road
CrossesMill Brook
Coordinates43.60090, -71.94009

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length41.7 ft (12.7 m)
Max Span38.7 ft (11.8 m)
Deck Width17.7 ft (5.4 m)
Deck Area68.6 sq m
Main Spans1
Year Built2005

Traffic

Avg Daily Traffic96 (2023)
Truck Traffic4%
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number009901610013500

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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