Structure 5201540012300 · Merrimack County, NH

I-393 US 4 Us202 over Merrimack River

Carries I-393 US 4 Us202 over Merrimack River, 0.6 Mi East Of Jct I-93.

Overall conditionFair

Set by its lowest-rated component: Substructure at 6 of 9.

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT525 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

525 ft end to end, longest span 200 ft: about 7 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 multi-beam bridge.

Built1978rebuilt 2003
Length524.9 ft160 m
Daily traffic40,527counted 2023
Last inspectedAugust 2023every 24 months

Location

StateNew Hampshire
CountyMerrimack
Location0.6 Mi East Of Jct I-93
CarriesI-393 US 4 Us202
CrossesMerrimack River
Coordinates43.21950, -71.52335

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length524.9 ft (160 m)
Max Span200.1 ft (61 m)
Deck Width91.9 ft (28 m)
Deck Area4,480 sq m
Main Spans3
Year Built1978 (reconstructed 2003)

Traffic

Avg Daily Traffic40,527 (2023)
Truck Traffic6%
Lanes On Bridge5

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number005201540012300

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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