Structure B166009PMDOTNBI · Suffolk County, MA

I 93 & Rmp Sa-cn over Water Charles Riv/ramps

Carries I 93 & Rmp Sa-cn over Water Charles Riv/ramps, N Of Td Garden.

Overall conditionFair

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

How ratings work
Deck6/9 · Satisfactory
Superstructure6/9 · Satisfactory
Substructuresets the rating5/9 · Fair
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT1,457 FT OVERALL250 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 6/9Substructure 5/9 · sets the rating

1,457 ft end to end, longest span 745 ft: about 4.0 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 cable-stayed bridge.

Built200224 years old
Length1457.3 ft444.2 m
Daily traffic155,200counted 2019
Last inspectedOctober 2023every 24 months

Location

StateMassachusetts
CountySuffolk
LocationN Of Td Garden
CarriesI 93 & Rmp Sa-cn
CrossesWater Charles Riv/ramps
Coordinates42.36880, -71.06323

Physical Characteristics

MaterialSteel
DesignStayed Girder
Total Length1457.3 ft (444.2 m)
Max Span745.1 ft (227.1 m)
Deck Width183.4 ft (55.9 m)
Deck Area24830.8 sq m
Main Spans5
Year Built2002

Traffic

Avg Daily Traffic155,200 (2019)
Truck Traffic8%
Lanes On Bridge10
Lanes Under Bridge3

Inspection & Ownership

Last InspectionOctober 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is eligible for the National Register
Scour Critical8 — Stable, low risk
Structure NumberB166009PMDOTNBI

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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