US Bridges

I029 S over Six Mile Ck

Fair

Brookings County, South Dakota · 1.1 N US14 By-Pass · Structure no. 000000006184139

Built
1970
55 years old
Condition
Fair
inspected August 2023
Type
Slab
Concrete Continuous
Length
129 ft
5 main spans
Daily traffic
6,165
2024 count
Owner
State
State Highway Agency

About this bridge

I029 S over Six Mile Ck is a concrete continuous slab carrying I029 S over Six Mile Ck in Brookings County, South Dakota. It was built in 1970, so it is 55 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 6,165 vehicles a day, roughly 23% of them trucks, projected to reach 10,030 by 2044. The structure is 129 ft (39.2 m) long and 41 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

CarriesI029 S
CrossesSix Mile Ck
Location1.1 N US14 By-Pass
RouteInterstate 29
Coordinates44.34256, -96.75825
Functional classRural Principal Arterial - Interstate

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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating65.5 US tons
Inventory rating39.2 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20 + Mod
Structure length129 ft (39.2 m)
Longest span26 ft (7.9 m)
Deck width41 ft (12.4 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,165 (2024)
Projected traffic10,030 by 2044
Trucks23%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed0.6 mi (1 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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—
NavigationNo navigation control on waterway

Frequently asked questions

When was I029 S over Six Mile Ck built?

It was built in 1970, making it 55 years old in 2025.

What condition is I029 S 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 August 2023.

How much traffic does I029 S over Six Mile Ck carry?

About 6,165 vehicles per day (2024 count), of which roughly 23% are trucks.

How long is I029 S over Six Mile Ck?

The structure is 129 ft (39.2 m) long with a longest span of 26 ft (7.9 m) and a deck 41 ft wide.

Who owns I029 S over Six Mile Ck?

It is owned by the State Highway Agency.