US Bridges

Manistique Lake Ro over Portage Creek

Fair

Mackinac County, Michigan · 1.5 MI N of Curtis · Structure no. 000000000005983

Built
1960
65 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
40 ft
1 main span
Daily traffic
1,762
2020 count
Owner
County
County Highway Agency

About this bridge

Manistique Lake Ro over Portage Creek is a steel stringer/multi-beam or girder carrying Manistique Lake Ro over Portage Creek in Mackinac County, Michigan. It was built in 1960, 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 1,762 vehicles a day, roughly 5% of them trucks, projected to reach 2,150 by 2040. The structure is 40 ft (12.2 m) long and 35 ft wide. If it were closed, the detour would be 16.8 mi (27 km).

Location

Open in Google Maps
CarriesManistique Lake Ro
CrossesPortage Creek
Location1.5 MI N of Curtis
RouteCounty Highway 4915
CountyMackinac County
StateMichigan
Coordinates46.21664, -85.72606
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating65.4 US tons
Inventory rating50.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length40 ft (12.2 m)
Longest span35 ft (10.6 m)
Deck width35 ft (10.6 m)
Roadway width31 ft (9.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,762 (2020)
Projected traffic2,150 by 2040
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.8 mi (27 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Manistique Lake Ro over Portage Creek built?

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

What condition is Manistique Lake Ro over Portage Creek 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 October 2023.

How much traffic does Manistique Lake Ro over Portage Creek carry?

About 1,762 vehicles per day (2020 count), of which roughly 5% are trucks.

How long is Manistique Lake Ro over Portage Creek?

The structure is 40 ft (12.2 m) long with a longest span of 35 ft (10.6 m) and a deck 35 ft wide.

Who owns Manistique Lake Ro over Portage Creek?

It is owned by the County Highway Agency.