US Bridges

Herron Road over Thunder Bay River

Fair

Alpena County, Michigan · 0.3 MI S of FAS RTE 191 · Structure no. 000000000000347

Built
1972
53 years old
Condition
Fair
inspected August 2024
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
140 ft
3 main spans
Daily traffic
300
2010 count
Owner
County
County Highway Agency

About this bridge

Herron Road over Thunder Bay River is a prestressed concrete box beam or girders - multiple carrying Herron Road over Thunder Bay River in Alpena County, Michigan. It was built in 1972, so it is 53 years old, older 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 300 vehicles a day, projected to reach 350 by 2030. The structure is 140 ft (42.6 m) long and 31 ft wide. If it were closed, the detour would be 16.8 mi (27 km).

Location

Open in Google Maps
CarriesHerron Road
CrossesThunder Bay River
Location0.3 MI S of FAS RTE 191
RouteCounty Highway 443
CountyAlpena County
StateMichigan
Coordinates45.12415, -83.63514
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating57.5 US tons
Inventory rating44.3 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans3
Design loadHS 20
Structure length140 ft (42.6 m)
Longest span60 ft (18.2 m)
Deck width31 ft (9.3 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic300 (2010)
Projected traffic350 by 2030
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.8 mi (27 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 Herron Road over Thunder Bay River built?

It was built in 1972, making it 53 years old in 2025.

What condition is Herron Road over 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 August 2024.

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

About 300 vehicles per day (2010 count).

How long is Herron Road over Thunder Bay River?

The structure is 140 ft (42.6 m) long with a longest span of 60 ft (18.2 m) and a deck 31 ft wide.

Who owns Herron Road over Thunder Bay River?

It is owned by the County Highway Agency.