Structure 27701320012700 · Hillsborough County, NH

Nh 31 over Stony Brook

Carries Nh 31 over Stony Brook, 0.4 Mi From Jct RTE 101.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT57 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 6/9

57 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 deck arch.

Built1905121 years old
Length57.1 ft17.4 m
Daily traffic2,883counted 2023
Last inspectedApril 2024every 24 months

Location

StateNew Hampshire
CountyHillsborough
Location0.4 Mi From Jct RTE 101
CarriesNh 31
CrossesStony Brook
Coordinates42.84454, -71.73886

Physical Characteristics

MaterialMasonry
DesignArch - Deck
Total Length57.1 ft (17.4 m)
Max Span49.9 ft (15.2 m)
Deck Width29.9 ft (9.1 m)
Deck Area158.3 sq m
Main Spans1
Year Built1905

Traffic

Avg Daily Traffic2,883 (2023)
Truck Traffic4%
Lanes On Bridge2

Inspection & Ownership

Last InspectionApril 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number027701320012700

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.

Nearby Bridges