Structure 800830009800 · Merrimack County, NH

Bridge Road over Blackwater River

Carries Bridge Road over Blackwater River, 0.1 Mi S Nh 11.

Overall conditionPoor

Set by its lowest-rated component: Superstructure at 4 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating4/9 · Poor
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT65 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 4/9 · sets the ratingSubstructure 7/9

65 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 through truss.

Built1882144 years old
Length65.0 ft19.8 m
Daily traffic96counted 2023
Last inspectedOctober 2024every 16 months

Location

StateNew Hampshire
CountyMerrimack
Location0.1 Mi S Nh 11
CarriesBridge Road
CrossesBlackwater River
Coordinates43.43498, -71.83616

Physical Characteristics

MaterialWood or Timber
DesignTruss - Thru
Total Length65.0 ft (19.8 m)
Max Span51.8 ft (15.8 m)
Deck Width19.0 ft (5.8 m)
Deck Area114.8 sq m
Main Spans1
Year Built1882

Traffic

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

Inspection & Ownership

Last InspectionOctober 2024
Inspection FrequencyEvery 16 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000800830009800

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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