Structure 14400770010700 · Grafton County, NH

US 4 Nh 10 over Mascoma River Csx

Carries US 4 Nh 10 over Mascoma River Csx, 4.3 Mi Lebanon T.l..

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT383 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

383 ft end to end, longest span 150 ft: about 5 semi-trucks nose to tail. Lengths and the semi-truck 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 girder bridge.

Built1945rebuilt 2008
Length382.9 ft116.7 m
Daily traffic13,685counted 2023
Last inspectedMay 2021every 24 months

Location

StateNew Hampshire
CountyGrafton
Location4.3 Mi Lebanon T.l.
CarriesUS 4 Nh 10
CrossesMascoma River Csx
Coordinates43.63572, -72.29543

Physical Characteristics

MaterialSteel Continuous
DesignGirder and Floorbeam
Total Length382.9 ft (116.7 m)
Max Span149.9 ft (45.7 m)
Deck Width40.0 ft (12.2 m)
Deck Area1423.7 sq m
Main Spans3
Year Built1945 (reconstructed 2008)

Traffic

Avg Daily Traffic13,685 (2023)
Truck Traffic5%
Lanes On Bridge2

Inspection & Ownership

Last InspectionMay 2021
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number014400770010700

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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