US Bridges

US 20B over US 20;N.RIGBY Ic

Fair

Jefferson County, Idaho · 0.7 N. Rigby · Structure no. 000000000012720

Built
1975
50 years old
Condition
Fair
inspected March 2023
Type
Box Beam or Girders - Single or Spread
Concrete Continuous
Length
229 ft
2 main spans
Daily traffic
9,500
2023 count
Owner
State
State Highway Agency

About this bridge

US 20B over US 20;N.RIGBY Ic is a concrete continuous box beam or girders - single or spread carrying US 20B over US 20;N.RIGBY Ic in Jefferson County, Idaho. It was built in 1975, so it is 50 years old, older than the Idaho average of 45.3 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 9,500 vehicles a day, roughly 4% of them trucks, projected to reach 14,250 by 2042. The structure is 229 ft (69.8 m) long and 47 ft wide.

Location

Open in Google Maps
CarriesUS 20B
CrossesUS 20;N.RIGBY Ic
Location0.7 N. Rigby
RouteU.S. Route 20
CountyJefferson County
StateIdaho
Coordinates43.68236, -111.90556
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2023
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
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating58 US tons
Inventory rating43 US tons

Structure

Structure typeBox Beam or Girders - Single or Spread
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length229 ft (69.8 m)
Longest span112 ft (34.1 m)
Deck width47 ft (14.2 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,500 (2023)
Projected traffic14,250 by 2042
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was US 20B over US 20;N.RIGBY Ic built?

It was built in 1975, making it 50 years old in 2025.

What condition is US 20B over US 20;N.RIGBY Ic 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 March 2023.

How much traffic does US 20B over US 20;N.RIGBY Ic carry?

About 9,500 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is US 20B over US 20;N.RIGBY Ic?

The structure is 229 ft (69.8 m) long with a longest span of 112 ft (34.1 m) and a deck 47 ft wide.

Who owns US 20B over US 20;N.RIGBY Ic?

It is owned by the State Highway Agency.