US Bridges

M-66 over Grand River

Fair

Ionia County, Michigan · In Ionia · Structure no. 000000000003970

Built
1948
77 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
374 ft
5 main spans
Daily traffic
17,638
2015 count
Owner
State
State Highway Agency

About this bridge

M-66 over Grand River is a steel stringer/multi-beam or girder carrying M-66 over Grand River in Ionia County, Michigan. It was built in 1948, so it is 77 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 17,638 vehicles a day, roughly 3% of them trucks, projected to reach 22,870 by 2018. The structure is 374 ft (114 m) long and 60 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesM-66
CrossesGrand River
LocationIn Ionia
RouteState Highway 66
CountyIonia County
StateMichigan
Coordinates42.97227, -85.0693
Functional classUrban Minor Arterial

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating71.8 US tons
Inventory rating42.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length374 ft (114 m)
Longest span75 ft (22.9 m)
Deck width60 ft (18.2 m)
Roadway width46 ft (14 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic17,638 (2015)
Projected traffic22,870 by 2018
Trucks3%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

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—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-66 over Grand River built?

It was built in 1948, making it 77 years old in 2025.

What condition is M-66 over Grand 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 September 2023.

How much traffic does M-66 over Grand River carry?

About 17,638 vehicles per day (2015 count), of which roughly 3% are trucks.

How long is M-66 over Grand River?

The structure is 374 ft (114 m) long with a longest span of 75 ft (22.9 m) and a deck 60 ft wide.

Who owns M-66 over Grand River?

It is owned by the State Highway Agency.