US Bridges

Dunbar RD over I-75

Fair

Monroe County, Michigan · 2.8 MI SW of M-50 · Structure no. 000000000007184

Built
1955
70 years old
Condition
Fair
inspected June 2023
Type
Tee Beam
Concrete Continuous
Length
236 ft
4 main spans
Daily traffic
400
1995 count
Owner
State
State Highway Agency

About this bridge

Dunbar RD over I-75 is a concrete continuous tee beam carrying Dunbar RD over I-75 in Monroe County, Michigan. It was built in 1955, so it is 70 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 400 vehicles a day, projected to reach 400 by 2015. The structure is 236 ft (71.9 m) long and 31 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesDunbar RD
CrossesI-75
Location2.8 MI SW of M-50
RouteCounty Highway 0
CountyMonroe County
StateMichigan
Coordinates41.89015, -83.38254
Functional classUrban Local

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJune 2023
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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment7: Better than present minimum criteria
Operating rating64.6 US tons
Inventory rating38.6 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 15
Structure length236 ft (71.9 m)
Longest span70 ft (21.3 m)
Deck width31 ft (9.5 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic400 (1995)
Projected traffic400 by 2015
Trucks—
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedDeck replacement with only incidental widening
Estimated improvement cost$97,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was Dunbar RD over I-75 built?

It was built in 1955, making it 70 years old in 2025.

What condition is Dunbar RD over I-75 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 June 2023.

How much traffic does Dunbar RD over I-75 carry?

About 400 vehicles per day (1995 count).

How long is Dunbar RD over I-75?

The structure is 236 ft (71.9 m) long with a longest span of 70 ft (21.3 m) and a deck 31 ft wide.

Who owns Dunbar RD over I-75?

It is owned by the State Highway Agency.