US Bridges

N Mackinaw HWY over I-75 NB

Fair

Cheboygan County, Michigan · @ I-75 Old M-108 JCT · Structure no. 000000000001520

Built
1959
66 years old
Condition
Fair
inspected April 2024
Type
Tee Beam
Concrete Continuous
Length
282 ft
4 main spans
Daily traffic
2,675
2014 count
Owner
State
State Highway Agency

About this bridge

N Mackinaw HWY over I-75 NB is a concrete continuous tee beam carrying N Mackinaw HWY over I-75 NB in Cheboygan County, Michigan. It was built in 1959, so it is 66 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 2,675 vehicles a day, roughly 5% of them trucks, projected to reach 2,950 by 2034. The structure is 282 ft (85.9 m) long and 33 ft wide.

Location

Open in Google Maps
CarriesN Mackinaw HWY
CrossesI-75 NB
Location@ I-75 Old M-108 JCT
RouteCounty Highway 0
CountyCheboygan County
StateMichigan
Coordinates45.76265, -84.73209
Functional classRural Major Collector

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionApril 2024
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 geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating63.6 US tons
Inventory rating37.8 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadH 15
Structure length282 ft (85.9 m)
Longest span83 ft (25.2 m)
Deck width33 ft (10.2 m)
Roadway width29 ft (8.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,675 (2014)
Projected traffic2,950 by 2034
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
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 proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was N Mackinaw HWY over I-75 NB built?

It was built in 1959, making it 66 years old in 2025.

What condition is N Mackinaw HWY 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 2024.

How much traffic does N Mackinaw HWY over I-75 NB carry?

About 2,675 vehicles per day (2014 count), of which roughly 5% are trucks.

How long is N Mackinaw HWY over I-75 NB?

The structure is 282 ft (85.9 m) long with a longest span of 83 ft (25.2 m) and a deck 33 ft wide.

Who owns N Mackinaw HWY over I-75 NB?

It is owned by the State Highway Agency.