US Bridges

US 20 over I 84 Eb-Wb;parma Ic

Fair

Canyon County, Idaho · 0.7 W. Caldwell Nwcl · Structure no. 000000000012220

Built
1964
61 years old, rebuilt 1979
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
212 ft
4 main spans
Daily traffic
6,500
2023 count
Owner
State
State Highway Agency

About this bridge

US 20 over I 84 Eb-Wb;parma Ic is a steel stringer/multi-beam or girder carrying US 20 over I 84 Eb-Wb;parma Ic in Canyon County, Idaho. It was built in 1964 and reconstructed in 1979, so it is 61 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 6,500 vehicles a day, roughly 12% of them trucks, projected to reach 9,750 by 2042. The structure is 212 ft (64.6 m) long and 31 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesUS 20
CrossesI 84 Eb-Wb;parma Ic
Location0.7 W. Caldwell Nwcl
RouteU.S. Route 20
CountyCanyon County
StateIdaho
Coordinates43.69022, -116.69333
Functional classUrban Other Principal Arterial

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 geometry4: Meets minimum tolerable limits to be left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating61.9 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length212 ft (64.6 m)
Longest span64 ft (19.5 m)
Deck width31 ft (9.5 m)
Roadway width29 ft (8.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,500 (2023)
Projected traffic9,750 by 2042
Trucks12%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed5 mi (8 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$3.7 million (2019 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was US 20 over I 84 Eb-Wb;parma Ic built?

It was built in 1964, making it 61 years old in 2025. It was reconstructed in 1979.

What condition is US 20 over I 84 Eb-Wb;parma 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 20 over I 84 Eb-Wb;parma Ic carry?

About 6,500 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is US 20 over I 84 Eb-Wb;parma Ic?

The structure is 212 ft (64.6 m) long with a longest span of 64 ft (19.5 m) and a deck 31 ft wide.

Who owns US 20 over I 84 Eb-Wb;parma Ic?

It is owned by the State Highway Agency.