Structure 25001460003700 · Merrimack County, NH

Roby Road over Lane River

Carries Roby Road over Lane River, 1.2 Mi. Warner 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
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT50 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 8/9Substructure 7/9 · sets the rating

50 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.

Built200224 years old
Length49.9 ft15.2 m
Daily traffic326counted 2023
Last inspectedSeptember 2024every 24 months

Location

StateNew Hampshire
CountyMerrimack
Location1.2 Mi. Warner Tl
CarriesRoby Road
CrossesLane River
Coordinates43.29707, -71.90482

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length49.9 ft (15.2 m)
Max Span43.3 ft (13.2 m)
Deck Width24.0 ft (7.3 m)
Deck Area111.0 sq m
Main Spans1
Year Built2002

Traffic

Avg Daily Traffic326 (2023)
Truck Traffic4%
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2024
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number025001460003700

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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