US Bridges

US-31 over Grand River M-104 Conn

Fair

Ottawa County, Michigan · Grand Haven-Ferrysburg · Structure no. 000000000008699

Built
1960
65 years old
Condition
Fair
inspected May 2024
Type
Movable - Bascule
Steel
Length
693 ft
1 main span
Daily traffic
66,750
2021 count
Owner
State
State Highway Agency

About this bridge

US-31 over Grand River M-104 Conn is a steel movable - bascule carrying US-31 over Grand River M-104 Conn in Ottawa 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 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 66,750 vehicles a day, roughly 3% of them trucks, projected to reach 73,750 by 2041. The structure is 693 ft (211.1 m) long and 95 ft wide. If it were closed, the detour would be 34.8 mi (56 km).

Location

Open in Google Maps
CarriesUS-31
CrossesGrand River M-104 Conn
LocationGrand Haven-Ferrysburg
RouteU.S. Route 31
CountyOttawa County
StateMichigan
Coordinates43.07597, -86.21731
Functional classUrban Other Principal 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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 15 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating60.7 US tons
Inventory rating36.4 US tons

Structure

Structure typeMovable - Bascule
MaterialSteel
DeckOpen grating
Main spans1 (+6 approach)
Design loadHS 20
Structure length693 ft (211.1 m)
Longest span226 ft (69 m)
Deck width95 ft (29.1 m)
Roadway width79 ft (24 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic66,750 (2021)
Projected traffic73,750 by 2041
Trucks3%
Lanes on structure6
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway and waterway
Detour if closed34.8 mi (56 km)
TollOn a free road
National Highway SystemYes

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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was US-31 over Grand River M-104 Conn built?

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

What condition is US-31 over Grand River M-104 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 May 2024.

How much traffic does US-31 over Grand River M-104 Conn carry?

About 66,750 vehicles per day (2021 count), of which roughly 3% are trucks.

How long is US-31 over Grand River M-104 Conn?

The structure is 693 ft (211.1 m) long with a longest span of 226 ft (69 m) and a deck 95 ft wide.

Who owns US-31 over Grand River M-104 Conn?

It is owned by the State Highway Agency.