US Bridges

M-99 NB over Grand River

Fair

Eaton County, Michigan · 0.5 MI S of Holt RD · Structure no. 000000000002304

Built
1978
47 years old
Condition
Fair
inspected May 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
179 ft
3 main spans
Daily traffic
4,238
2007 count
Owner
State
State Highway Agency

About this bridge

M-99 NB over Grand River is a steel stringer/multi-beam or girder carrying M-99 NB over Grand River in Eaton County, Michigan. It was built in 1978, so it is 47 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 4,238 vehicles a day, roughly 4% of them trucks, projected to reach 9,000 by 2028. The structure is 179 ft (54.6 m) long and 46 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesM-99 NB
CrossesGrand River
Location0.5 MI S of Holt RD
RouteState Highway 99
CountyEaton County
StateMichigan
Coordinates42.63117, -84.62269
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
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 geometry8: Equal to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating87.5 US tons
Inventory rating52.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length179 ft (54.6 m)
Longest span60 ft (18.3 m)
Deck width46 ft (14 m)
Roadway width42 ft (12.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,238 (2007)
Projected traffic9,000 by 2028
Trucks4%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-99 NB over Grand River built?

It was built in 1978, making it 47 years old in 2025.

What condition is M-99 NB over Grand 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 May 2023.

How much traffic does M-99 NB over Grand River carry?

About 4,238 vehicles per day (2007 count), of which roughly 4% are trucks.

How long is M-99 NB over Grand River?

The structure is 179 ft (54.6 m) long with a longest span of 60 ft (18.3 m) and a deck 46 ft wide.

Who owns M-99 NB over Grand River?

It is owned by the State Highway Agency.