US Bridges

I-75 SB over Allen RD

Fair

Wayne County, Michigan · S Lts of Southgate · Structure no. 000000000011659

Built
1966
59 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
218 ft
4 main spans
Daily traffic
46,853
2015 count
Owner
State
State Highway Agency

About this bridge

I-75 SB over Allen RD is a steel continuous stringer/multi-beam or girder carrying I-75 SB over Allen RD in Wayne County, Michigan. It was built in 1966, so it is 59 years old, older than the Michigan average of 48.3 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 46,853 vehicles a day, roughly 20% of them trucks, projected to reach 52,548 by 2038. The structure is 218 ft (66.5 m) long and 54 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-75 SB
CrossesAllen RD
LocationS Lts of Southgate
RouteInterstate 75
CountyWayne County
StateMichigan
Coordinates42.20826, -83.22901
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating57.9 US tons
Inventory rating34.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length218 ft (66.5 m)
Longest span62 ft (18.9 m)
Deck width54 ft (16.6 m)
Roadway width52 ft (15.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic46,853 (2015)
Projected traffic52,548 by 2038
Trucks20%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 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 proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-75 SB over Allen RD built?

It was built in 1966, making it 59 years old in 2025.

What condition is I-75 SB over Allen RD 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 September 2024.

How much traffic does I-75 SB over Allen RD carry?

About 46,853 vehicles per day (2015 count), of which roughly 20% are trucks.

How long is I-75 SB over Allen RD?

The structure is 218 ft (66.5 m) long with a longest span of 62 ft (18.9 m) and a deck 54 ft wide.

Who owns I-75 SB over Allen RD?

It is owned by the State Highway Agency.