Structure B160554T0DOTNBI · Suffolk County, MA

US 20 Comm Av/mbta over Comb I 90 & Mbta/csx

Carries US 20 Comm Av/mbta over Comb I 90 & Mbta/csx, .1mi.s.storrow DR S48.

Overall conditionGood

Set by its lowest-rated component: Deck and Superstructure and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · Good
Substructuresets the rating7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT380 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

380 ft end to end, longest span 152 ft: about 5 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.

Built1965rebuilt 2018
Length379.9 ft115.8 m
Daily traffic40,783counted 2018
Last inspectedMarch 2023every 24 months

Location

StateMassachusetts
CountySuffolk
Location.1mi.s.storrow DR S48
CarriesUS 20 Comm Av/mbta
CrossesComb I 90 & Mbta/csx
Coordinates42.35060, -71.11127

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length379.9 ft (115.8 m)
Max Span151.9 ft (46.3 m)
Deck Width162.1 ft (49.4 m)
Deck Area5720.5 sq m
Main Spans3
Year Built1965 (reconstructed 2018)

Traffic

Avg Daily Traffic40,783 (2018)
Truck Traffic8%
Lanes On Bridge5
Lanes Under Bridge8

Inspection & Ownership

Last InspectionMarch 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure NumberB160554T0DOTNBI

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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