US Bridges

Airport Road over Thunder Bay River

Good

Montmorency County, Michigan · Sections 7-18 Avery Twp · Structure no. 000000000012719

Built
1969
56 years old
Condition
Good
inspected November 2023
Type
Culvert
Steel
Length
38 ft
4 main spans
Daily traffic
160
2005 count
Owner
County
County Highway Agency

About this bridge

Airport Road over Thunder Bay River is a steel culvert carrying Airport Road over Thunder Bay River in Montmorency County, Michigan. It was built in 1969, so it is 56 years old, older than the Michigan average of 48.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 160 vehicles a day, roughly 10% of them trucks, projected to reach 260 by 2025. The structure is 38 ft (11.6 m) long. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesAirport Road
CrossesThunder Bay River
LocationSections 7-18 Avery Twp
RouteCounty Highway 0
CountyMontmorency County
StateMichigan
Coordinates45.00035, -84.11883
Functional classRural Local

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection7 GoodSome minor problems.
Culvert7 GoodSome minor problems.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating107.1 US tons
Inventory rating85.3 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans4
Design loadH 20
Structure length38 ft (11.6 m)
Longest span7 ft (2.2 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic160 (2005)
Projected traffic260 by 2025
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$603,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Airport Road over Thunder Bay River built?

It was built in 1969, making it 56 years old in 2025.

What condition is Airport Road over Thunder Bay River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in November 2023.

How much traffic does Airport Road over Thunder Bay River carry?

About 160 vehicles per day (2005 count), of which roughly 10% are trucks.

How long is Airport Road over Thunder Bay River?

The structure is 38 ft (11.6 m) long with a longest span of 7 ft (2.2 m).

Who owns Airport Road over Thunder Bay River?

It is owned by the County Highway Agency.