Structure 3501330014500 · Grafton County, NH

I-93 NB over Owl Street

Carries I-93 NB over Owl Street, 0.7 Mi Thornton Tl.

Overall conditionGood

Set by its lowest-rated component: Substructure at 7 of 9.

How ratings work
Deck8/9 · Very Good
Superstructure8/9 · Very Good
Substructuresets the rating7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

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

76 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.

Built1968rebuilt 2002
Length76.1 ft23.2 m
Daily traffic7,498counted 2023
Last inspectedApril 2023every 24 months

Location

StateNew Hampshire
CountyGrafton
Location0.7 Mi Thornton Tl
CarriesI-93 NB
CrossesOwl Street
Coordinates43.85969, -71.65214

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length76.1 ft (23.2 m)
Max Span69.9 ft (21.3 m)
Deck Width44.0 ft (13.4 m)
Deck Area310.9 sq m
Main Spans1
Year Built1968 (reconstructed 2002)

Traffic

Avg Daily Traffic7,498 (2023)
Truck Traffic10%
Lanes On Bridge2
Lanes Under Bridge2

Inspection & Ownership

Last InspectionApril 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number003501330014500

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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