US Bridges

Thornville Road over South Br. Flint River

Fair

Lapeer County, Michigan · Sec. 7 Dryden Twp. · Structure no. 000000000005416

Built
1986
39 years old
Condition
Fair
inspected June 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
42 ft
1 main span
Daily traffic
283
2021 count
Owner
County
County Highway Agency

About this bridge

Thornville Road over South Br. Flint River is a prestressed concrete box beam or girders - multiple carrying Thornville Road over South Br. Flint River in Lapeer County, Michigan. It was built in 1986, so it is 39 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 283 vehicles a day, roughly 5% of them trucks, projected to reach 346 by 2041. The structure is 42 ft (12.9 m) long and 32 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesThornville Road
CrossesSouth Br. Flint River
LocationSec. 7 Dryden Twp.
RouteCounty Highway 0
CountyLapeer County
StateMichigan
Coordinates42.94436, -83.2238
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
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 evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating68.2 US tons
Inventory rating41.1 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length42 ft (12.9 m)
Longest span41 ft (12.5 m)
Deck width32 ft (9.7 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic283 (2021)
Projected traffic346 by 2041
Trucks5%
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 Thornville Road over South Br. Flint River built?

It was built in 1986, making it 39 years old in 2025.

What condition is Thornville Road over South Br. Flint 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 Thornville Road over South Br. Flint River carry?

About 283 vehicles per day (2021 count), of which roughly 5% are trucks.

How long is Thornville Road over South Br. Flint River?

The structure is 42 ft (12.9 m) long with a longest span of 41 ft (12.5 m) and a deck 32 ft wide.

Who owns Thornville Road over South Br. Flint River?

It is owned by the County Highway Agency.