US Bridges

HWY Mishawum ST over ST 99 Sullivan Sq Undrps

Poor

Suffolk County, Massachusetts · 1.6 KM N of N Wshngton ST · Structure no. B1624537UMUNNBI

Built
1951
74 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
73 ft
1 main span
Daily traffic
2,845
2024 count
Owner
City
City or Municipal Highway Agency

About this bridge

HWY Mishawum ST over ST 99 Sullivan Sq Undrps is a steel stringer/multi-beam or girder carrying HWY Mishawum ST over ST 99 Sullivan Sq Undrps in Suffolk County, Massachusetts. It was built in 1951, 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 poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. Its operating status is: open, would be posted or closed except for temporary shoring.

It carries about 2,845 vehicles a day, roughly 9% of them trucks, projected to reach 9,318 by 2033. The structure is 73 ft (22.3 m) long and 55 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesHWY Mishawum ST
CrossesST 99 Sullivan Sq Undrps
Location1.6 KM N of N Wshngton ST
RouteCity Street 0
Coordinates42.38303, -71.07299
Functional classUrban Other Principal Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2024
Inspection intervalevery 12 months
Operating statusOpen, would be posted or closed except for temporary shoring
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating52.4 US tons
Inventory rating31.4 US tons

Structure

MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length73 ft (22.3 m)
Longest span67 ft (20.4 m)
Deck width55 ft (16.8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deck16 ft (4.9 m)

Traffic and service

Average daily traffic2,845 (2024)
Projected traffic9,318 by 2033
Trucks9%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$9.2 million (2025 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was HWY Mishawum ST over ST 99 Sullivan Sq Undrps built?

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

What condition is HWY Mishawum ST over ST 99 Sullivan Sq Undrps in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in August 2024.

How much traffic does HWY Mishawum ST over ST 99 Sullivan Sq Undrps carry?

About 2,845 vehicles per day (2024 count), of which roughly 9% are trucks.

How long is HWY Mishawum ST over ST 99 Sullivan Sq Undrps?

The structure is 73 ft (22.3 m) long with a longest span of 67 ft (20.4 m) and a deck 55 ft wide.

Who owns HWY Mishawum ST over ST 99 Sullivan Sq Undrps?

It is owned by the City or Municipal Highway Agency.