US Bridges

CO Road 451 over N Br Thunder Bay River

Fair

Montmorency County, Michigan · Sec 1 Montmorency Twp E · Structure no. 000000000007546

Built
1994
31 years old
Condition
Fair
inspected November 2024
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
58 ft
1 main span
Daily traffic
2,126
2021 count
Owner
County
County Highway Agency

About this bridge

CO Road 451 over N Br Thunder Bay River is a prestressed concrete box beam or girders - multiple carrying CO Road 451 over N Br Thunder Bay River in Montmorency County, Michigan. It was built in 1994, so it is 31 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 2,126 vehicles a day, roughly 10% of them trucks, projected to reach 2,445 by 2041. The structure is 58 ft (17.6 m) long and 37 ft wide. If it were closed, the detour would be 14.9 mi (24 km).

Location

Open in Google Maps
CarriesCO Road 451
CrossesN Br Thunder Bay River
LocationSec 1 Montmorency Twp E
RouteCounty Highway 6097
CountyMontmorency County
StateMichigan
Coordinates45.19163, -83.89145
Functional classRural Major Collector

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating68.6 US tons
Inventory rating37.5 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length58 ft (17.6 m)
Longest span56 ft (17 m)
Deck width37 ft (11.4 m)
Roadway width35 ft (10.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,126 (2021)
Projected traffic2,445 by 2041
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 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 CO Road 451 over N Br Thunder Bay River built?

It was built in 1994, making it 31 years old in 2025.

What condition is CO Road 451 over N Br Thunder Bay 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 November 2024.

How much traffic does CO Road 451 over N Br Thunder Bay River carry?

About 2,126 vehicles per day (2021 count), of which roughly 10% are trucks.

How long is CO Road 451 over N Br Thunder Bay River?

The structure is 58 ft (17.6 m) long with a longest span of 56 ft (17 m) and a deck 37 ft wide.

Who owns CO Road 451 over N Br Thunder Bay River?

It is owned by the County Highway Agency.