US Bridges

M-99 M-50 over Spring Brook

Fair

Eaton County, Michigan · In Eaton Rapids · Structure no. 000000000002300

Built
1988
37 years old
Condition
Fair
inspected May 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
42 ft
1 main span
Daily traffic
15,977
2007 count
Owner
State
State Highway Agency

About this bridge

M-99 M-50 over Spring Brook is a prestressed concrete box beam or girders - multiple carrying M-99 M-50 over Spring Brook in Eaton County, Michigan. It was built in 1988, so it is 37 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 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 15,977 vehicles a day, roughly 5% of them trucks, projected to reach 21,679 by 2018. The structure is 42 ft (12.8 m) long and 68 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesM-99 M-50
CrossesSpring Brook
LocationIn Eaton Rapids
RouteState Highway 99
CountyEaton County
StateMichigan
Coordinates42.5139, -84.65574
Functional classRural 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating60.7 US tons
Inventory rating30.3 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length42 ft (12.8 m)
Longest span41 ft (12.4 m)
Deck width68 ft (20.6 m)
Roadway width48 ft (14.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,977 (2007)
Projected traffic21,679 by 2018
Trucks5%
Lanes on structure3
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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$333,000
NavigationNo navigation control on waterway

Frequently asked questions

When was M-99 M-50 over Spring Brook built?

It was built in 1988, making it 37 years old in 2025.

What condition is M-99 M-50 over Spring Brook 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 M-99 M-50 over Spring Brook carry?

About 15,977 vehicles per day (2007 count), of which roughly 5% are trucks.

How long is M-99 M-50 over Spring Brook?

The structure is 42 ft (12.8 m) long with a longest span of 41 ft (12.4 m) and a deck 68 ft wide.

Who owns M-99 M-50 over Spring Brook?

It is owned by the State Highway Agency.