US Bridges

S 3100 W over Texas Slough;se.Thornton

Fair

Madison County, Idaho · 1.0 S. 0.2 E. Thornton · Structure no. 000000000032880

Built
1978
47 years old
Condition
Fair
inspected April 2023
Type
Frame
Concrete
Length
36 ft
1 main span
Daily traffic
70
2023 count
Owner
County
County Highway Agency

About this bridge

S 3100 W over Texas Slough;se.Thornton is a concrete frame carrying S 3100 W over Texas Slough;se.Thornton in Madison County, Idaho. It was built in 1978, so it is 47 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 6 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 70 vehicles a day, roughly 10% of them trucks, projected to reach 105 by 2039. The structure is 36 ft (11 m) long and 30 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesS 3100 W
CrossesTexas Slough;se.Thornton
Location1.0 S. 0.2 E. Thornton
RouteCounty Highway 0
CountyMadison County
StateIdaho
Coordinates43.74253, -111.84028
Functional classRural Local

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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating38 US tons
Inventory rating23 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length36 ft (11 m)
Longest span36 ft (11 m)
Deck width30 ft (9.1 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic70 (2023)
Projected traffic105 by 2039
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 S 3100 W over Texas Slough;se.Thornton built?

It was built in 1978, making it 47 years old in 2025.

What condition is S 3100 W over Texas Slough;se.Thornton 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 April 2023.

How much traffic does S 3100 W over Texas Slough;se.Thornton carry?

About 70 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is S 3100 W over Texas Slough;se.Thornton?

The structure is 36 ft (11 m) long with a longest span of 36 ft (11 m) and a deck 30 ft wide.

Who owns S 3100 W over Texas Slough;se.Thornton?

It is owned by the County Highway Agency.