US Bridges

Twnshp RD 186th ST over Cobb Ck

PoorPosted for load

Deuel County, South Dakota · 4S & 5.1E Clear Lake · Structure no. 000000020151200

Built
1950
75 years old, rebuilt 1982
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
28 ft
1 main span
Daily traffic
45
2022 count
Owner
County
County Highway Agency

About this bridge

Twnshp RD 186th ST over Cobb Ck is a steel stringer/multi-beam or girder carrying Twnshp RD 186th ST over Cobb Ck in Deuel County, South Dakota. It was built in 1950 and reconstructed in 1982, so it is 75 years old, older than the South Dakota average of 48.9 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 load restriction.

It carries about 45 vehicles a day, roughly 2% of them trucks, projected to reach 45 by 2032. The structure is 28 ft (8.6 m) long and 26 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

CarriesTwnshp RD 186th ST
CrossesCobb Ck
Location4S & 5.1E Clear Lake
RouteCounty Highway 0
Coordinates44.68874, -96.58092
Functional classRural Local

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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating24 US tons
Inventory rating12.1 US tons

Structure

MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadUnknown
Structure length28 ft (8.6 m)
Longest span27 ft (8.2 m)
Deck width26 ft (7.9 m)
Roadway width26 ft (7.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic45 (2022)
Projected traffic45 by 2032
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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$500,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Twnshp RD 186th ST over Cobb Ck built?

It was built in 1950, making it 75 years old in 2025. It was reconstructed in 1982.

What condition is Twnshp RD 186th ST over Cobb Ck 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 August 2024.

How much traffic does Twnshp RD 186th ST over Cobb Ck carry?

About 45 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is Twnshp RD 186th ST over Cobb Ck?

The structure is 28 ft (8.6 m) long with a longest span of 27 ft (8.2 m) and a deck 26 ft wide.

Who owns Twnshp RD 186th ST over Cobb Ck?

It is owned by the County Highway Agency.