Structure M18050464DOTNBI · Plymouth County, MA

I 495 over Rr Mbta/csx Qnb 20.82

Carries I 495 over Rr Mbta/csx Qnb 20.82, Csx Track Mp Qnb 20.82.

Overall conditionFair

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

How ratings work
Deck7/9 · Good
Superstructuresets the rating6/9 · Satisfactory
Substructuresets the rating6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
CAR · 15 FT95 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 6/9 · sets the ratingSubstructure 6/9 · sets the rating

95 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 multi-beam bridge.

Built195868 years old
Length95.1 ft29 m
Daily traffic47,237counted 2022
Last inspectedSeptember 2023every 24 months

Location

StateMassachusetts
CountyPlymouth
LocationCsx Track Mp Qnb 20.82
CarriesI 495
CrossesRr Mbta/csx Qnb 20.82
Coordinates41.88660, -70.93113

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length95.1 ft (29 m)
Max Span84.0 ft (25.6 m)
Deck Width127.6 ft (38.9 m)
Deck Area1128.1 sq m
Main Spans1
Year Built1958

Traffic

Avg Daily Traffic47,237 (2022)
Truck Traffic4%
Lanes On Bridge4

Inspection & Ownership

Last InspectionSeptember 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour CriticalNot applicable
Structure NumberM18050464DOTNBI

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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