US Bridges

STC6705;ST Clair over W. Branch Sand Creek

Fair

Bonneville County, Idaho · 3.8 S. 1.9 E. Idaho Falls · Structure no. 000000000020800

Built
1966
59 years old
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
44 ft
1 main span
Daily traffic
2,500
2023 count
Owner
City
City or Municipal Highway Agency

About this bridge

STC6705;ST Clair over W. Branch Sand Creek is a prestressed concrete stringer/multi-beam or girder carrying STC6705;ST Clair over W. Branch Sand Creek in Bonneville County, Idaho. It was built in 1966, so it is 59 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 2,500 vehicles a day, roughly 4% of them trucks, projected to reach 3,750 by 2042. The structure is 44 ft (13.4 m) long and 39 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesSTC6705;ST Clair
CrossesW. Branch Sand Creek
Location3.8 S. 1.9 E. Idaho Falls
RouteCounty Highway 6705
CountyBonneville County
StateIdaho
Coordinates43.43633, -112.00386
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
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 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
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 rating30 US tons
Inventory rating18 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length44 ft (13.4 m)
Longest span42 ft (12.8 m)
Deck width39 ft (11.9 m)
Roadway width34 ft (10.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,500 (2023)
Projected traffic3,750 by 2042
Trucks4%
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

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$696,000 (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was STC6705;ST Clair over W. Branch Sand Creek built?

It was built in 1966, making it 59 years old in 2025.

What condition is STC6705;ST Clair over W. Branch Sand Creek 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 2024.

How much traffic does STC6705;ST Clair over W. Branch Sand Creek carry?

About 2,500 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is STC6705;ST Clair over W. Branch Sand Creek?

The structure is 44 ft (13.4 m) long with a longest span of 42 ft (12.8 m) and a deck 39 ft wide.

Who owns STC6705;ST Clair over W. Branch Sand Creek?

It is owned by the City or Municipal Highway Agency.