US Bridges

I-75 Bl over I-75 NB

Fair

Mackinac County, Michigan · @ N JCT I-75 Bl · Structure no. 000000000005952

Built
1960
65 years old, rebuilt 2015
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
245 ft
4 main spans
Daily traffic
4,350
2015 count
Owner
State
State Highway Agency

About this bridge

I-75 Bl over I-75 NB is a steel stringer/multi-beam or girder carrying I-75 Bl over I-75 NB in Mackinac County, Michigan. It was built in 1960 and reconstructed in 2015, so it is 65 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 6 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 4,350 vehicles a day, roughly 3% of them trucks, projected to reach 5,050 by 2035. The structure is 245 ft (74.7 m) long and 37 ft wide.

Location

Open in Google Maps
CarriesI-75 Bl
CrossesI-75 NB
Location@ N JCT I-75 Bl
RouteInterstate 75
CountyMackinac County
StateMichigan
Coordinates45.90753, -84.74002
Functional classRural 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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating91.4 US tons
Inventory rating55 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length245 ft (74.7 m)
Longest span78 ft (23.9 m)
Deck width37 ft (11.2 m)
Roadway width33 ft (10 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,350 (2015)
Projected traffic5,050 by 2035
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemNo

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 Bl over I-75 NB built?

It was built in 1960, making it 65 years old in 2025. It was reconstructed in 2015.

What condition is I-75 Bl over I-75 NB 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 April 2023.

How much traffic does I-75 Bl over I-75 NB carry?

About 4,350 vehicles per day (2015 count), of which roughly 3% are trucks.

How long is I-75 Bl over I-75 NB?

The structure is 245 ft (74.7 m) long with a longest span of 78 ft (23.9 m) and a deck 37 ft wide.

Who owns I-75 Bl over I-75 NB?

It is owned by the State Highway Agency.