Structure B162813BMDOTNBI · Suffolk County, MA

I 93 NB over I 93 SB Bt 46 - 57

Carries I 93 NB over I 93 SB Bt 46 - 57, .5 Mi N Of Jct I93&us1.

Overall conditionFair

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

How ratings work
Decksets the rating5/9 · Fair
Superstructure6/9 · Satisfactory
Substructure6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT898 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 6/9Substructure 6/9

898 ft end to end, longest span 82 ft: about 2.5 football fields. 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.

Built197056 years old
Length898.0 ft273.7 m
Daily traffic75,910counted 2023
Last inspectedApril 2024every 24 months

Location

StateMassachusetts
CountySuffolk
Location.5 Mi N Of Jct I93&us1
CarriesI 93 NB
CrossesI 93 SB Bt 46 - 57
Coordinates42.37717, -71.07500

Physical Characteristics

MaterialSteel
DesignGirder and Floorbeam
Total Length898.0 ft (273.7 m)
Max Span82.0 ft (25 m)
Deck Width68.9 ft (21 m)
Deck Area5747.7 sq m
Main Spans11
Year Built1970

Traffic

Avg Daily Traffic75,910 (2023)
Truck Traffic11%
Lanes On Bridge3
Lanes Under Bridge3

Inspection & Ownership

Last InspectionApril 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberB162813BMDOTNBI

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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