US Bridges

Cth N over Koshkonong Creek

FairPosted for load

Dane County, Wisconsin · 1.0M N JCT Cth Tt · Structure no. B13008100000000

Built
1957
68 years old
Condition
Fair
inspected October 2024
Type
Slab
Concrete
Length
33 ft
1 main span
Daily traffic
6,200
2022 count
Owner
County
County Highway Agency

About this bridge

Cth N over Koshkonong Creek is a concrete slab carrying Cth N over Koshkonong Creek in Dane County, Wisconsin. It was built in 1957, so it is 68 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. Its operating status is: posted for other load-capacity restriction.

It carries about 6,200 vehicles a day, projected to reach 7,440 by 2042. The structure is 33 ft (10.1 m) long and 34 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

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CarriesCth N
CrossesKoshkonong Creek
Location1.0M N JCT Cth Tt
RouteCounty Highway 0N
CountyDane County
StateWisconsin
Coordinates43.12636, -89.19831
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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusPosted for other load-capacity restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41.4 US tons
Inventory rating23.3 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length33 ft (10.1 m)
Longest span32 ft (9.9 m)
Deck width34 ft (10.5 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,200 (2022)
Projected traffic7,440 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$272,000 (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Cth N over Koshkonong Creek built?

It was built in 1957, making it 68 years old in 2025.

What condition is Cth N over Koshkonong Creek 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 2024.

How much traffic does Cth N over Koshkonong Creek carry?

About 6,200 vehicles per day (2022 count).

How long is Cth N over Koshkonong Creek?

The structure is 33 ft (10.1 m) long with a longest span of 32 ft (9.9 m) and a deck 34 ft wide.

Who owns Cth N over Koshkonong Creek?

It is owned by the County Highway Agency.