US Bridges

Sth 77 over Potato River

Fair

Iron County, Wisconsin · 8.2M E Ashland CO Line · Structure no. B26001700000000

Built
1983
42 years old
Condition
Fair
inspected July 2024
Type
Culvert
Concrete
Length
29 ft
2 main spans
Daily traffic
1,000
2023 count
Owner
State
State Highway Agency

About this bridge

Sth 77 over Potato River is a concrete culvert carrying Sth 77 over Potato River in Iron County, Wisconsin. It was built in 1983, so it is 42 years old, older than the Wisconsin average of 40.3 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 1,000 vehicles a day, roughly 16% of them trucks, projected to reach 980 by 2043. The structure is 29 ft (8.8 m) long. If it were closed, the detour would be 30.4 mi (49 km).

Location

Open in Google Maps
CarriesSth 77
CrossesPotato River
Location8.2M E Ashland CO Line
RouteState Highway 77
CountyIron County
StateWisconsin
Coordinates46.36656, -90.41077
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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.4 US tons
Inventory rating35.7 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length29 ft (8.8 m)
Longest span12 ft (3.7 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,000 (2023)
Projected traffic980 by 2043
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed30.4 mi (49 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 Sth 77 over Potato River built?

It was built in 1983, making it 42 years old in 2025.

What condition is Sth 77 over Potato 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 July 2024.

How much traffic does Sth 77 over Potato River carry?

About 1,000 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is Sth 77 over Potato River?

The structure is 29 ft (8.8 m) long with a longest span of 12 ft (3.7 m).

Who owns Sth 77 over Potato River?

It is owned by the State Highway Agency.