US Bridges

ST 1 a over HWY Bningtn & Neptune

Fair

Suffolk County, Massachusetts · 1 MI N of Callahan Tun. · Structure no. B1623639WDOTNBI

Built
1951
74 years old, rebuilt 1977
Condition
Fair
inspected January 2022
Type
Stringer/Multi-beam or Girder
Steel
Length
710 ft
10 main spans
Daily traffic
33,770
2018 count
Owner
State
State Highway Agency

About this bridge

ST 1 a over HWY Bningtn & Neptune is a steel stringer/multi-beam or girder carrying ST 1 a over HWY Bningtn & Neptune 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 33,770 vehicles a day, roughly 15% of them trucks, projected to reach 900,517 by 2033. The structure is 710 ft (216.4 m) long and 120 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesST 1 a
CrossesHWY Bningtn & Neptune
Location1 MI N of Callahan Tun.
RouteState Highway 1A
CountySuffolk County
StateMassachusetts
Coordinates42.38003, -71.02476
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJanuary 2022
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 geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating67.9 US tons
Inventory rating40.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans10
Design loadHS 20
Structure length710 ft (216.4 m)
Longest span80 ft (24.4 m)
Deck width120 ft (36.7 m)
Roadway width117 ft (35.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic33,770 (2018)
Projected traffic900,517 by 2033
Trucks15%
Lanes on structure6
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
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$77.6 million (2025 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was ST 1 a over HWY Bningtn & Neptune built?

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

What condition is ST 1 a over HWY Bningtn & Neptune 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 2022.

How much traffic does ST 1 a over HWY Bningtn & Neptune carry?

About 33,770 vehicles per day (2018 count), of which roughly 15% are trucks.

How long is ST 1 a over HWY Bningtn & Neptune?

The structure is 710 ft (216.4 m) long with a longest span of 80 ft (24.4 m) and a deck 120 ft wide.

Who owns ST 1 a over HWY Bningtn & Neptune?

It is owned by the State Highway Agency.