US Bridges

I-69 EB over Colby Lake RD

Fair

Shiawassee County, Michigan · 1.5 MI W of Shaftsburg · Structure no. 000000000009764

Built
1989
36 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
101 ft
1 main span
Daily traffic
20,138
2020 count
Owner
State
State Highway Agency

About this bridge

I-69 EB over Colby Lake RD is a prestressed concrete stringer/multi-beam or girder carrying I-69 EB over Colby Lake RD in Shiawassee County, Michigan. It was built in 1989, so it is 36 years old, younger 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 20,138 vehicles a day, roughly 15% of them trucks, projected to reach 22,263 by 2040. The structure is 101 ft (30.7 m) long and 47 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesI-69 EB
CrossesColby Lake RD
Location1.5 MI W of Shaftsburg
RouteInterstate 69
CountyShiawassee County
StateMichigan
Coordinates42.80624, -84.32282
Functional classRural 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
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 geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating84.7 US tons
Inventory rating46.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length101 ft (30.7 m)
Longest span98 ft (29.9 m)
Deck width47 ft (14.4 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20,138 (2020)
Projected traffic22,263 by 2040
Trucks15%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.1 mi (5 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-69 EB over Colby Lake RD built?

It was built in 1989, making it 36 years old in 2025.

What condition is I-69 EB over Colby Lake 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 June 2023.

How much traffic does I-69 EB over Colby Lake RD carry?

About 20,138 vehicles per day (2020 count), of which roughly 15% are trucks.

How long is I-69 EB over Colby Lake RD?

The structure is 101 ft (30.7 m) long with a longest span of 98 ft (29.9 m) and a deck 47 ft wide.

Who owns I-69 EB over Colby Lake RD?

It is owned by the State Highway Agency.