US Bridges

ST 1 A/Off Ramp over HWY M Caughlin & Relie

Fair

Suffolk County, Massachusetts · .8 MI NE of Callahan Tun. · Structure no. B1623639PDOTNBI

Built
1951
74 years old, rebuilt 1977
Condition
Fair
inspected January 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
304 ft
4 main spans
Daily traffic
12,413
2024 count
Owner
State
State Highway Agency

About this bridge

ST 1 A/Off Ramp over HWY M Caughlin & Relie is a steel stringer/multi-beam or girder carrying ST 1 A/Off Ramp over HWY M Caughlin & Relie in Suffolk County, Massachusetts. It was built in 1951 and reconstructed in 1977, so it is 74 years old, older 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 12,413 vehicles a day, roughly 9% of them trucks, projected to reach 23,374 by 2033. The structure is 304 ft (92.7 m) long and 30 ft wide.

Location

Open in Google Maps
CarriesST 1 A/Off Ramp
CrossesHWY M Caughlin & Relie
Location.8 MI NE of Callahan Tun.
RouteState Highway 1A
CountySuffolk County
StateMassachusetts
Coordinates42.37907, -71.02534
Functional classUrban Minor Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJanuary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating69.4 US tons
Inventory rating41.7 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length304 ft (92.7 m)
Longest span80 ft (24.4 m)
Deck width30 ft (9.1 m)
Roadway width25 ft (7.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,413 (2024)
Projected traffic23,374 by 2033
Trucks9%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
Detour if closed—
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$8.2 million (2025 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was ST 1 A/Off Ramp over HWY M Caughlin & Relie built?

It was built in 1951, making it 74 years old in 2025. It was reconstructed in 1977.

What condition is ST 1 A/Off Ramp over HWY M Caughlin & Relie 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 January 2024.

How much traffic does ST 1 A/Off Ramp over HWY M Caughlin & Relie carry?

About 12,413 vehicles per day (2024 count), of which roughly 9% are trucks.

How long is ST 1 A/Off Ramp over HWY M Caughlin & Relie?

The structure is 304 ft (92.7 m) long with a longest span of 80 ft (24.4 m) and a deck 30 ft wide.

Who owns ST 1 A/Off Ramp over HWY M Caughlin & Relie?

It is owned by the State Highway Agency.