Structure 301740011600 · Grafton County, NH

Bog Road over Patten Brook

Carries Bog Road over Patten Brook, 0.5mi S Alexandria Ctr.

Overall conditionFair

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

How ratings work
Deck8/9 · Very Good
Superstructure8/9 · Very Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT30 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 8/9Substructure 6/9 · sets the rating

30 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.

Built1950rebuilt 2014
Length29.9 ft9.1 m
Daily traffic96counted 2023
Last inspectedAugust 2023every 24 months

Location

StateNew Hampshire
CountyGrafton
Location0.5mi S Alexandria Ctr
CarriesBog Road
CrossesPatten Brook
Coordinates43.60824, -71.79322

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length29.9 ft (9.1 m)
Max Span25.9 ft (7.9 m)
Deck Width16.1 ft (4.9 m)
Deck Area44.6 sq m
Main Spans1
Year Built1950 (reconstructed 2014)

Traffic

Avg Daily Traffic96 (2023)
Truck Traffic4%
Lanes On Bridge1

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical4 — Foundations need monitoring
Structure Number000301740011600

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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