US Bridges

US 20 over Henrys Fk. Snake River

Good

Fremont County, Idaho · 17.8 N. Ashton · Structure no. 000000000012676

Built
2001
24 years old
Condition
Good
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
255 ft
2 main spans
Daily traffic
6,400
2023 count
Owner
State
State Highway Agency

About this bridge

US 20 over Henrys Fk. Snake River is a steel continuous stringer/multi-beam or girder carrying US 20 over Henrys Fk. Snake River in Fremont County, Idaho. It was built in 2001, so it is 24 years old, younger than the Idaho average of 45.3 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 6,400 vehicles a day, roughly 21% of them trucks, projected to reach 9,600 by 2042. The structure is 255 ft (77.7 m) long and 41 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesUS 20
CrossesHenrys Fk. Snake River
Location17.8 N. Ashton
RouteU.S. Route 20
CountyFremont County
StateIdaho
Coordinates44.32444, -111.44889
Functional classRural Principal Arterial - Other

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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating63.1 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 25 or greater
Structure length255 ft (77.7 m)
Longest span125 ft (38.1 m)
Deck width41 ft (12.6 m)
Roadway width39 ft (11.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,400 (2023)
Projected traffic9,600 by 2042
Trucks21%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 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$3.2 million (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was US 20 over Henrys Fk. Snake River built?

It was built in 2001, making it 24 years old in 2025.

What condition is US 20 over Henrys Fk. Snake River 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 July 2024.

How much traffic does US 20 over Henrys Fk. Snake River carry?

About 6,400 vehicles per day (2023 count), of which roughly 21% are trucks.

How long is US 20 over Henrys Fk. Snake River?

The structure is 255 ft (77.7 m) long with a longest span of 125 ft (38.1 m) and a deck 41 ft wide.

Who owns US 20 over Henrys Fk. Snake River?

It is owned by the State Highway Agency.