Structure 15400890018700 · Rockingham County, NH

Manter Mill Road over Cohas Brook

Carries Manter Mill Road over Cohas Brook, 0.25ml Junc. Old Derry RD.

Overall conditionGood

Set by its lowest-rated component: Culvert at 8 of 9.

How ratings work
Culvertsets the rating8/9 · Very Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT34 FT ACROSS25 FT0ELEVATION · LENGTHS TO SCALE
Culvert 8/9

A culvert 34 ft across. 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, so those are drawn as typical for a culvert.

Built200026 years old
Length34.1 ft10.4 m
Daily traffic511counted 2023
Last inspectedSeptember 2023every 24 months

Location

StateNew Hampshire
CountyRockingham
Location0.25ml Junc. Old Derry RD
CarriesManter Mill Road
CrossesCohas Brook
Coordinates42.93792, -71.37020

Physical Characteristics

MaterialConcrete
DesignCulvert
Total Length34.1 ft (10.4 m)
Max Span32.2 ft (9.8 m)
Deck Area75.9 sq m
Main Spans1
Year Built2000

Traffic

Avg Daily Traffic511 (2023)
Lanes On Bridge2

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number015400890018700

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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