US Bridges

Cth T over Koshkonong Creek

PoorPosted for load

Dane County, Wisconsin · 0.3M W JCT Cth N · Structure no. B13048000000000

Built
1939
86 years old
Condition
Poor
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
29 ft
1 main span
Daily traffic
1,716
2023 count
Owner
County
County Highway Agency

About this bridge

Cth T over Koshkonong Creek is a steel stringer/multi-beam or girder carrying Cth T over Koshkonong Creek in Dane County, Wisconsin. It was built in 1939, so it is 86 years old, older than the Wisconsin average of 40.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. Its operating status is: posted for other load-capacity restriction.

It carries about 1,716 vehicles a day, projected to reach 972 by 2042. The structure is 29 ft (8.7 m) long and 33 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

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CarriesCth T
CrossesKoshkonong Creek
Location0.3M W JCT Cth N
RouteCounty Highway 0T
CountyDane County
StateWisconsin
Coordinates43.14164, -89.21333
Functional classRural Minor Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure4 PoorAdvanced section loss, deterioration, 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 inspectionOctober 2024
Inspection intervalevery 12 months
Operating statusPosted for other load-capacity restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating43.2 US tons
Inventory rating25 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length29 ft (8.7 m)
Longest span27 ft (8.2 m)
Deck width33 ft (10 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,716 (2023)
Projected traffic972 by 2042
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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$211,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Cth T over Koshkonong Creek built?

It was built in 1939, making it 86 years old in 2025.

What condition is Cth T over Koshkonong Creek in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in October 2024.

How much traffic does Cth T over Koshkonong Creek carry?

About 1,716 vehicles per day (2023 count).

How long is Cth T over Koshkonong Creek?

The structure is 29 ft (8.7 m) long with a longest span of 27 ft (8.2 m) and a deck 33 ft wide.

Who owns Cth T over Koshkonong Creek?

It is owned by the County Highway Agency.