US Bridges

409th Ave over North Br Twelve Mile Ck

Poor

Davison County, South Dakota · 2.3 N & 2 W Ethan · Structure no. 000000018150187

Built
1945
80 years old, rebuilt 1965
Condition
Poor
inspected August 2024
Type
Slab
Concrete
Length
35 ft
3 main spans
Daily traffic
64
2022 count
Owner
County
County Highway Agency

About this bridge

409th Ave over North Br Twelve Mile Ck is a concrete slab carrying 409th Ave over North Br Twelve Mile Ck in Davison County, South Dakota. It was built in 1945 and reconstructed in 1965, so it is 80 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.

It carries about 64 vehicles a day, roughly 2% of them trucks, projected to reach 64 by 2032. The structure is 35 ft (10.7 m) long and 34 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Carries409th Ave
CrossesNorth Br Twelve Mile Ck
Location2.3 N & 2 W Ethan
RouteCounty Highway 0
Coordinates43.57757, -98.02587
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
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.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry8: Equal to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36 US tons
Inventory rating21.6 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadUnknown
Structure length35 ft (10.7 m)
Longest span10 ft (3 m)
Deck width34 ft (10.5 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic64 (2022)
Projected traffic64 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was 409th Ave over North Br Twelve Mile Ck built?

It was built in 1945, making it 80 years old in 2025. It was reconstructed in 1965.

What condition is 409th Ave over North Br Twelve Mile 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 409th Ave over North Br Twelve Mile Ck carry?

About 64 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is 409th Ave over North Br Twelve Mile Ck?

The structure is 35 ft (10.7 m) long with a longest span of 10 ft (3 m) and a deck 34 ft wide.

Who owns 409th Ave over North Br Twelve Mile Ck?

It is owned by the County Highway Agency.