US Bridges

Royston over Big Thornapple Drain

Fair

Eaton County, Michigan · 2 MI SE Potterville · Structure no. 000000000002376

Built
1952
73 years old
Condition
Fair
inspected May 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
43 ft
1 main span
Daily traffic
78
2011 count
Owner
County
County Highway Agency

About this bridge

Royston over Big Thornapple Drain is a prestressed concrete box beam or girders - multiple carrying Royston over Big Thornapple Drain in Eaton County, Michigan. It was built in 1952, so it is 73 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 78 vehicles a day, projected to reach 200 by 2013. The structure is 43 ft (13.1 m) long and 24 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesRoyston
CrossesBig Thornapple Drain
Location2 MI SE Potterville
RouteCounty Highway 0
CountyEaton County
StateMichigan
Coordinates42.60287, -84.71934
Functional classRural Local

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment7: Better than present minimum criteria
Operating rating60.1 US tons
Inventory rating36 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length43 ft (13.1 m)
Longest span32 ft (9.7 m)
Deck width24 ft (7.4 m)
Roadway width23 ft (7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic78 (2011)
Projected traffic200 by 2013
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 Royston over Big Thornapple Drain built?

It was built in 1952, making it 73 years old in 2025.

What condition is Royston over Big Thornapple Drain 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 2023.

How much traffic does Royston over Big Thornapple Drain carry?

About 78 vehicles per day (2011 count).

How long is Royston over Big Thornapple Drain?

The structure is 43 ft (13.1 m) long with a longest span of 32 ft (9.7 m) and a deck 24 ft wide.

Who owns Royston over Big Thornapple Drain?

It is owned by the County Highway Agency.