US Bridges

I 93 NB over I 93 SB Bt 46 - 57

Fair

Suffolk County, Massachusetts · .5 MI N of JCT I93&US1 · Structure no. B162813BMDOTNBI

Built
1970
55 years old
Condition
Fair
inspected April 2024
Type
Girder and Floorbeam System
Steel
Length
898 ft
11 main spans
Daily traffic
75,910
2023 count
Owner
State
State Highway Agency

About this bridge

I 93 NB over I 93 SB Bt 46 - 57 is a steel girder and floorbeam system carrying I 93 NB over I 93 SB Bt 46 - 57 in Suffolk County, Massachusetts. It was built in 1970, so it is 55 years old, younger than the Massachusetts average of 63.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 75,910 vehicles a day, roughly 11% of them trucks, projected to reach 152,245 by 2031. The structure is 898 ft (273.7 m) long and 69 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

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CarriesI 93 NB
CrossesI 93 SB Bt 46 - 57
Location.5 MI N of JCT I93&US1
RouteInterstate 93
CountySuffolk County
StateMassachusetts
Coordinates42.37717, -71.075
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment7: Better than present minimum criteria
Operating rating60.7 US tons
Inventory rating36.4 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel
DeckConcrete, cast-in-place
Main spans11
Design loadHS 20
Structure length898 ft (273.7 m)
Longest span82 ft (25 m)
Deck width69 ft (21 m)
Roadway width62 ft (18.9 m)
Vertical clearance over deck16 ft (4.8 m)

Traffic and service

Average daily traffic75,910 (2023)
Projected traffic152,245 by 2031
Trucks11%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedDeck rehabilitation with only incidental widening
Estimated improvement cost$26.9 million (2025 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 93 NB over I 93 SB Bt 46 - 57 built?

It was built in 1970, making it 55 years old in 2025.

What condition is I 93 NB over I 93 SB Bt 46 - 57 in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in April 2024.

How much traffic does I 93 NB over I 93 SB Bt 46 - 57 carry?

About 75,910 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is I 93 NB over I 93 SB Bt 46 - 57?

The structure is 898 ft (273.7 m) long with a longest span of 82 ft (25 m) and a deck 69 ft wide.

Who owns I 93 NB over I 93 SB Bt 46 - 57?

It is owned by the State Highway Agency.