US Bridges

I-75 SB over M-13 Conn

Fair

Bay County, Michigan · 2.5 MI S of Kawkawlin · Structure no. 000000000000629

Built
1968
57 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
160 ft
3 main spans
Daily traffic
11,225
2019 count
Owner
State
State Highway Agency

About this bridge

I-75 SB over M-13 Conn is a steel stringer/multi-beam or girder carrying I-75 SB over M-13 Conn in Bay County, Michigan. It was built in 1968, so it is 57 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 11,225 vehicles a day, roughly 9% of them trucks, projected to reach 12,909 by 2039. The structure is 160 ft (48.7 m) long and 42 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-75 SB
CrossesM-13 Conn
Location2.5 MI S of Kawkawlin
RouteInterstate 75
CountyBay County
StateMichigan
Coordinates43.61863, -83.94879
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
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionAugust 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 geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating80 US tons
Inventory rating47.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length160 ft (48.7 m)
Longest span68 ft (20.7 m)
Deck width42 ft (12.8 m)
Roadway width39 ft (11.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,225 (2019)
Projected traffic12,909 by 2039
Trucks9%
Lanes on structure2
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 M-13 Conn built?

It was built in 1968, making it 57 years old in 2025.

What condition is I-75 SB over M-13 Conn 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 August 2024.

How much traffic does I-75 SB over M-13 Conn carry?

About 11,225 vehicles per day (2019 count), of which roughly 9% are trucks.

How long is I-75 SB over M-13 Conn?

The structure is 160 ft (48.7 m) long with a longest span of 68 ft (20.7 m) and a deck 42 ft wide.

Who owns I-75 SB over M-13 Conn?

It is owned by the State Highway Agency.