US Bridges

IRR I029 over Twin City RR

Fair

Roberts County, South Dakota · 4.5 S Sd 10 Interch · Structure no. 000000055115238

Built
1982
43 years old
Condition
Fair
inspected July 2024
Type
Culvert
Steel
Length
82 ft
1 main span
Daily traffic
4,890
2023 count
Owner
State
State Highway Agency

About this bridge

IRR I029 over Twin City RR is a steel culvert carrying IRR I029 over Twin City RR in Roberts County, South Dakota. It was built in 1982, so it is 43 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 4,890 vehicles a day, roughly 27% of them trucks, projected to reach 6,366 by 2043. The structure is 82 ft (25 m) long. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesIRR I029
CrossesTwin City RR
Location4.5 S Sd 10 Interch
RouteInterstate 29
CountyRoberts County
StateSouth Dakota
Coordinates45.58967, -96.98921
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
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment9: Superior to present desirable criteria
Operating rating47.2 US tons
Inventory rating36.4 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans1
Design loadHS 20 + Mod
Structure length82 ft (25 m)
Longest span72 ft (21.8 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,890 (2023)
Projected traffic6,366 by 2043
Trucks27%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesRailroad
Detour if closed5 mi (8 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$8 million
NavigationNot applicable (no waterway)

Frequently asked questions

When was IRR I029 over Twin City RR built?

It was built in 1982, making it 43 years old in 2025.

What condition is IRR I029 over Twin City RR 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 July 2024.

How much traffic does IRR I029 over Twin City RR carry?

About 4,890 vehicles per day (2023 count), of which roughly 27% are trucks.

How long is IRR I029 over Twin City RR?

The structure is 82 ft (25 m) long with a longest span of 72 ft (21.8 m).

Who owns IRR I029 over Twin City RR?

It is owned by the State Highway Agency.