US Bridges

427 Ave over Rock Ck

PoorPosted for load

Miner County, South Dakota · 2.0E & 2.4S Carthage · Structure no. 000000049090044

Built
1930
95 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
25 ft
1 main span
Daily traffic
20
2022 count
Owner
County
County Highway Agency

About this bridge

427 Ave over Rock Ck is a steel stringer/multi-beam or girder carrying 427 Ave over Rock Ck in Miner County, South Dakota. It was built in 1930, so it is 95 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 20 vehicles a day, roughly 2% of them trucks, projected to reach 20 by 2032. The structure is 25 ft (7.6 m) long and 21 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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Carries427 Ave
CrossesRock Ck
Location2.0E & 2.4S Carthage
RouteCounty Highway 0
CountyMiner County
StateSouth Dakota
Coordinates44.13396, -97.67047
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
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating39.8 US tons
Inventory rating23.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckWood or timber
Main spans1
Design loadUnknown
Structure length25 ft (7.6 m)
Longest span23 ft (6.9 m)
Deck width21 ft (6.5 m)
Roadway width21 ft (6.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2022)
Projected traffic20 by 2032
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 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 427 Ave over Rock Ck built?

It was built in 1930, making it 95 years old in 2025.

What condition is 427 Ave over Rock 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 427 Ave over Rock Ck carry?

About 20 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is 427 Ave over Rock Ck?

The structure is 25 ft (7.6 m) long with a longest span of 23 ft (6.9 m) and a deck 21 ft wide.

Who owns 427 Ave over Rock Ck?

It is owned by the County Highway Agency.