US Bridges

306 ST (fas 6370) over I029

Fair

Union County, South Dakota · 9.0 S Sd 46 Interchange · Structure no. 000000064006090

Built
1960
65 years old, rebuilt 1988
Condition
Fair
inspected February 2025
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
252 ft
4 main spans
Daily traffic
270
2023 count
Owner
State
State Highway Agency

About this bridge

306 ST (fas 6370) over I029 is a steel continuous stringer/multi-beam or girder carrying 306 ST (fas 6370) over I029 in Union County, South Dakota. It was built in 1960 and reconstructed in 1988, so it is 65 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 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 270 vehicles a day, roughly 3% of them trucks, projected to reach 270 by 2043. The structure is 252 ft (76.9 m) long and 33 ft wide.

Location

Open in Google Maps
Carries306 ST (fas 6370)
CrossesI029
Location9.0 S Sd 46 Interchange
RouteCounty Highway 0
CountyUnion County
StateSouth Dakota
Coordinates42.95355, -96.79449
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating58.3 US tons
Inventory rating34.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length252 ft (76.9 m)
Longest span70 ft (21.3 m)
Deck width33 ft (10 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic270 (2023)
Projected traffic270 by 2043
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was 306 ST (fas 6370) over I029 built?

It was built in 1960, making it 65 years old in 2025. It was reconstructed in 1988.

What condition is 306 ST (fas 6370) over I029 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 February 2025.

How much traffic does 306 ST (fas 6370) over I029 carry?

About 270 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is 306 ST (fas 6370) over I029?

The structure is 252 ft (76.9 m) long with a longest span of 70 ft (21.3 m) and a deck 33 ft wide.

Who owns 306 ST (fas 6370) over I029?

It is owned by the State Highway Agency.