US Bridges

River Road over Au Sable River

Fair

Iosco County, Michigan · 0.5 MI W of US-23 · Structure no. 000000000004139

Built
1963
62 years old
Condition
Fair
inspected June 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
301 ft
7 main spans
Daily traffic
4,920
2006 count
Owner
County
County Highway Agency

About this bridge

River Road over Au Sable River is a prestressed concrete box beam or girders - multiple carrying River Road over Au Sable River in Iosco County, Michigan. It was built in 1963, so it is 62 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 4,920 vehicles a day, roughly 10% of them trucks, projected to reach 8,850 by 2026. The structure is 301 ft (91.7 m) long and 34 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesRiver Road
CrossesAu Sable River
Location0.5 MI W of US-23
RouteCounty Highway 0
CountyIosco County
StateMichigan
Coordinates44.42099, -83.34069
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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating74.6 US tons
Inventory rating35.4 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans7
Design loadH 20
Structure length301 ft (91.7 m)
Longest span43 ft (13.1 m)
Deck width34 ft (10.5 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,920 (2006)
Projected traffic8,850 by 2026
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed1.2 mi (2 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 River Road over Au Sable River built?

It was built in 1963, making it 62 years old in 2025.

What condition is River Road over Au Sable River 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 River Road over Au Sable River carry?

About 4,920 vehicles per day (2006 count), of which roughly 10% are trucks.

How long is River Road over Au Sable River?

The structure is 301 ft (91.7 m) long with a longest span of 43 ft (13.1 m) and a deck 34 ft wide.

Who owns River Road over Au Sable River?

It is owned by the County Highway Agency.