US Bridges

Mason Road over Thornapple Creek

Fair

Eaton County, Michigan · 1 Mi. W of Vermontville · Structure no. 000000000002420

Built
1989
36 years old
Condition
Fair
inspected May 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
90 ft
2 main spans
Daily traffic
200
2021 count
Owner
County
County Highway Agency

About this bridge

Mason Road over Thornapple Creek is a prestressed concrete box beam or girders - multiple carrying Mason Road over Thornapple Creek in Eaton County, Michigan. It was built in 1989, so it is 36 years old, younger 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 200 vehicles a day, roughly 1% of them trucks, projected to reach 221 by 2041. The structure is 90 ft (27.4 m) long and 31 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesMason Road
CrossesThornapple Creek
Location1 Mi. W of Vermontville
RouteCounty Highway 0
CountyEaton County
StateMichigan
Coordinates42.61758, -85.05435
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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating61.4 US tons
Inventory rating36.8 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans2
Design loadHS 20 + Mod
Structure length90 ft (27.4 m)
Longest span45 ft (13.7 m)
Deck width31 ft (9.5 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic200 (2021)
Projected traffic221 by 2041
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 Mason Road over Thornapple Creek built?

It was built in 1989, making it 36 years old in 2025.

What condition is Mason Road over Thornapple 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 May 2023.

How much traffic does Mason Road over Thornapple Creek carry?

About 200 vehicles per day (2021 count), of which roughly 1% are trucks.

How long is Mason Road over Thornapple Creek?

The structure is 90 ft (27.4 m) long with a longest span of 45 ft (13.7 m) and a deck 31 ft wide.

Who owns Mason Road over Thornapple Creek?

It is owned by the County Highway Agency.