US Bridges

473rd Avenue over Six Mile Ck

Fair

Brookings County, South Dakota · 2E & 2.4N Brookings · Structure no. 000000006190136

Built
1985
40 years old
Condition
Fair
inspected September 2023
Type
Tee Beam
Prestressed Concrete
Length
66 ft
1 main span
Daily traffic
92
2022 count
Owner
County
County Highway Agency

About this bridge

473rd Avenue over Six Mile Ck is a prestressed concrete tee beam carrying 473rd Avenue over Six Mile Ck in Brookings County, South Dakota. It was built in 1985, so it is 40 years old, younger than the South Dakota average of 48.9 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.

It carries about 92 vehicles a day, roughly 2% of them trucks, projected to reach 92 by 2032. The structure is 66 ft (20.1 m) long and 27 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
Carries473rd Avenue
CrossesSix Mile Ck
Location2E & 2.4N Brookings
RouteCounty Highway 0
CountyBrookings County
StateSouth Dakota
Coordinates44.34614, -96.74786
Functional classRural Local

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum 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 typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHS 20
Structure length66 ft (20.1 m)
Longest span65 ft (19.7 m)
Deck width27 ft (8.2 m)
Roadway width26 ft (8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic92 (2022)
Projected traffic92 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$1.2 million (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was 473rd Avenue over Six Mile Ck built?

It was built in 1985, making it 40 years old in 2025.

What condition is 473rd Avenue over Six Mile Ck 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 September 2023.

How much traffic does 473rd Avenue over Six Mile Ck carry?

About 92 vehicles per day (2022 count), of which roughly 2% are trucks.

How long is 473rd Avenue over Six Mile Ck?

The structure is 66 ft (20.1 m) long with a longest span of 65 ft (19.7 m) and a deck 27 ft wide.

Who owns 473rd Avenue over Six Mile Ck?

It is owned by the County Highway Agency.