US Bridges

IRR I029 N over 146 ST

Good

Grant County, South Dakota · 2 S Roberts CO Line · Structure no. 000000026085040

Built
1977
48 years old
Condition
Good
inspected November 2024
Type
Slab
Concrete Continuous
Length
119 ft
3 main spans
Daily traffic
3,650
2024 count
Owner
State
State Highway Agency

About this bridge

IRR I029 N over 146 ST is a concrete continuous slab carrying IRR I029 N over 146 ST in Grant County, South Dakota. It was built in 1977, so it is 48 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 good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 3,650 vehicles a day, roughly 40% of them trucks, projected to reach 5,146 by 2044. The structure is 119 ft (36.3 m) long and 43 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

CarriesIRR I029 N
Crosses146 ST
Location2 S Roberts CO Line
RouteInterstate 29
Coordinates45.26786, -97.0516
Functional classRural Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating81.1 US tons
Inventory rating48.6 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length119 ft (36.3 m)
Longest span43 ft (13 m)
Deck width43 ft (13 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,650 (2024)
Projected traffic5,146 by 2044
Trucks40%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was IRR I029 N over 146 ST built?

It was built in 1977, making it 48 years old in 2025.

What condition is IRR I029 N over 146 ST in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in November 2024.

How much traffic does IRR I029 N over 146 ST carry?

About 3,650 vehicles per day (2024 count), of which roughly 40% are trucks.

How long is IRR I029 N over 146 ST?

The structure is 119 ft (36.3 m) long with a longest span of 43 ft (13 m) and a deck 43 ft wide.

Who owns IRR I029 N over 146 ST?

It is owned by the State Highway Agency.