Structure 2701580013700 · Merrimack County, NH

I-93 Fee Tpk over Dow Road

Carries I-93 Fee Tpk over Dow Road, 1.7 Mi Jct I-89.

Overall conditionFair

Set by its lowest-rated component: Culvert at 5 of 9.

How ratings work
Culvertsets the rating5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT30 FT ACROSS25 FT0ELEVATION · LENGTHS TO SCALE
Culvert 5/9

A culvert 30 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.

Built1957rebuilt 1978
Length29.9 ft9.1 m
Daily traffic78,501counted 2023
Last inspectedApril 2024every 24 months

Location

StateNew Hampshire
CountyMerrimack
Location1.7 Mi Jct I-89
CarriesI-93 Fee Tpk
CrossesDow Road
Coordinates43.15406, -71.50710

Physical Characteristics

MaterialConcrete
DesignCulvert
Total Length29.9 ft (9.1 m)
Max Span29.9 ft (9.1 m)
Deck Area354.9 sq m
Main Spans1
Year Built1957 (reconstructed 1978)

Traffic

Avg Daily Traffic78,501 (2023)
Truck Traffic9%
Lanes On Bridge6
Lanes Under Bridge2

Inspection & Ownership

Last InspectionApril 2024
Inspection FrequencyEvery 24 months
OwnerState Toll Authority
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number002701580013700

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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