US Bridges

IH 43 NB over Sth 20

Fair

Walworth County, Wisconsin · 1.8 MI N JCT Sth 120 · Structure no. B64008800000000

Built
1971
54 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
210 ft
2 main spans
Daily traffic
11,550
2022 count
Owner
State
State Highway Agency

About this bridge

IH 43 NB over Sth 20 is a steel continuous stringer/multi-beam or girder carrying IH 43 NB over Sth 20 in Walworth County, Wisconsin. It was built in 1971, so it is 54 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 11,550 vehicles a day, roughly 16% of them trucks, projected to reach 13,860 by 2042. The structure is 210 ft (64 m) long and 48 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

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CarriesIH 43 NB
CrossesSth 20
Location1.8 MI N JCT Sth 120
RouteInterstate 43
CountyWalworth County
StateWisconsin
Coordinates42.79198, -88.3849
Functional classRural Principal Arterial - Interstate

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54 US tons
Inventory rating32.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length210 ft (64 m)
Longest span105 ft (31.9 m)
Deck width48 ft (14.6 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,550 (2022)
Projected traffic13,860 by 2042
Trucks16%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed0.6 mi (1 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was IH 43 NB over Sth 20 built?

It was built in 1971, making it 54 years old in 2025.

What condition is IH 43 NB over Sth 20 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 October 2023.

How much traffic does IH 43 NB over Sth 20 carry?

About 11,550 vehicles per day (2022 count), of which roughly 16% are trucks.

How long is IH 43 NB over Sth 20?

The structure is 210 ft (64 m) long with a longest span of 105 ft (31.9 m) and a deck 48 ft wide.

Who owns IH 43 NB over Sth 20?

It is owned by the State Highway Agency.