US Bridges

US 20 Wbl over Texas Slough

Good

Madison County, Idaho · At Thornton · Structure no. 000000000012520

Built
1981
44 years old
Condition
Good
inspected March 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
64 ft
1 main span
Daily traffic
15,250
2023 count
Owner
State
State Highway Agency

About this bridge

US 20 Wbl over Texas Slough is a prestressed concrete stringer/multi-beam or girder carrying US 20 Wbl over Texas Slough in Madison County, Idaho. It was built in 1981, so it is 44 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 15,250 vehicles a day, roughly 7% of them trucks, projected to reach 22,875 by 2042. The structure is 64 ft (19.5 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesUS 20 Wbl
CrossesTexas Slough
LocationAt Thornton
RouteU.S. Route 20
CountyMadison County
StateIdaho
Coordinates43.75556, -111.84944
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
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating64 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length64 ft (19.5 m)
Longest span61 ft (18.6 m)
Deck width44 ft (13.3 m)
Roadway width41 ft (12.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,250 (2023)
Projected traffic22,875 by 2042
Trucks7%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 20 Wbl over Texas Slough built?

It was built in 1981, making it 44 years old in 2025.

What condition is US 20 Wbl over Texas Slough 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 March 2024.

How much traffic does US 20 Wbl over Texas Slough carry?

About 15,250 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is US 20 Wbl over Texas Slough?

The structure is 64 ft (19.5 m) long with a longest span of 61 ft (18.6 m) and a deck 44 ft wide.

Who owns US 20 Wbl over Texas Slough?

It is owned by the State Highway Agency.