Structure B162813DWDOTNBI · Suffolk County, MA

I 93 NB Bt 38-46 over I 93 SB Bt 38-46

Carries I 93 NB Bt 38-46 over I 93 SB Bt 38-46, .7 Mi N Of Jct Us1&i93.

Overall conditionFair

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

How ratings work
Decksets the rating5/9 · Fair
Superstructuresets the rating5/9 · Fair
Substructuresets the rating5/9 · Fair
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT652 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9Superstructure 5/9Substructure 5/9

652 ft end to end, longest span 82 ft: about 1.8 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
Length651.9 ft198.7 m
Daily traffic81,000counted 2020
Last inspectedApril 2024every 24 months

Location

StateMassachusetts
CountySuffolk
Location.7 Mi N Of Jct Us1&i93
CarriesI 93 NB Bt 38-46
CrossesI 93 SB Bt 38-46
Coordinates42.37536, -71.07302

Physical Characteristics

MaterialSteel
DesignGirder and Floorbeam
Total Length651.9 ft (198.7 m)
Max Span82.0 ft (25 m)
Deck Width68.9 ft (21 m)
Deck Area4172.7 sq m
Main Spans8
Year Built1970

Traffic

Avg Daily Traffic81,000 (2020)
Truck Traffic8%
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 NumberB162813DWDOTNBI

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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