Structure 5500810009500 · Sullivan County, NH

Root Hill Road over Mill Brook

Carries Root Hill Road over Mill Brook, 1.3 Mi Nh 120.

Overall conditionFair

Set by its lowest-rated component: Superstructure and Substructure at 5 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating5/9 · Fair
Substructuresets the rating5/9 · Fair
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT78 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 5/9 · sets the ratingSubstructure 5/9 · sets the rating

78 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.

Built1883143 years old
Length78.1 ft23.8 m
Daily traffic92counted 2023
Last inspectedSeptember 2023every 24 months

Location

StateNew Hampshire
CountySullivan
Location1.3 Mi Nh 120
CarriesRoot Hill Road
CrossesMill Brook
Coordinates43.46440, -72.36928

Physical Characteristics

MaterialWood or Timber
DesignTruss - Thru
Total Length78.1 ft (23.8 m)
Max Span62.0 ft (18.9 m)
Deck Width16.1 ft (4.9 m)
Deck Area116.6 sq m
Main Spans1
Year Built1883

Traffic

Avg Daily Traffic92 (2023)
Truck Traffic4%
Lanes On Bridge1

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is on the National Register of Historic Places
Scour Critical8 — Stable, low risk
Structure Number005500810009500

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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