US Bridges

Cth M over Rock River

Fair

Rock County, Wisconsin · 0.1M S JCT Cth F to N · Structure no. B53001600000000

Built
1956
69 years old, rebuilt 2018
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
489 ft
6 main spans
Daily traffic
1,413
2023 count
Owner
County
County Highway Agency

About this bridge

Cth M over Rock River is a steel continuous stringer/multi-beam or girder carrying Cth M over Rock River in Rock County, Wisconsin. It was built in 1956 and reconstructed in 2018, so it is 69 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 6 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 1,413 vehicles a day, projected to reach 2,000 by 2042. The structure is 489 ft (149 m) long and 29 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesCth M
CrossesRock River
Location0.1M S JCT Cth F to N
RouteCounty Highway 0M
CountyRock County
StateWisconsin
Coordinates42.80383, -89.09017
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal 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 spans6
Design loadHS 20
Structure length489 ft (149 m)
Longest span80 ft (24.4 m)
Deck width29 ft (8.9 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,413 (2023)
Projected traffic2,000 by 2042
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed5 mi (8 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 Cth M over Rock River built?

It was built in 1956, making it 69 years old in 2025. It was reconstructed in 2018.

What condition is Cth M over Rock 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 2023.

How much traffic does Cth M over Rock River carry?

About 1,413 vehicles per day (2023 count).

How long is Cth M over Rock River?

The structure is 489 ft (149 m) long with a longest span of 80 ft (24.4 m) and a deck 29 ft wide.

Who owns Cth M over Rock River?

It is owned by the County Highway Agency.