US Bridges

SH 55 over Big Creek

Fair

Valley County, Idaho · 4 S. Cascade · Structure no. 000000000014820

Built
1933
92 years old, rebuilt 1955
Condition
Fair
inspected September 2024
Type
Tee Beam
Concrete
Length
53 ft
1 main span
Daily traffic
4,100
2023 count
Owner
State
State Highway Agency

About this bridge

SH 55 over Big Creek is a concrete tee beam carrying SH 55 over Big Creek in Valley County, Idaho. It was built in 1933 and reconstructed in 1955, so it is 92 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 4,100 vehicles a day, roughly 17% of them trucks, projected to reach 6,150 by 2042. The structure is 53 ft (16.2 m) long and 39 ft wide. If it were closed, the detour would be 14.3 mi (23 km).

CarriesSH 55
CrossesBig Creek
Location4 S. Cascade
RouteState Highway 55
StateIdaho
Coordinates44.46761, -115.99919
Functional classRural Principal Arterial - Other

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 protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to 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 rating51 US tons
Inventory rating30 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length53 ft (16.2 m)
Longest span51 ft (15.5 m)
Deck width39 ft (11.9 m)
Roadway width36 ft (11 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,100 (2023)
Projected traffic6,150 by 2042
Trucks17%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.3 mi (23 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$818,000 (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 55 over Big Creek built?

It was built in 1933, making it 92 years old in 2025. It was reconstructed in 1955.

What condition is SH 55 over Big 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 September 2024.

How much traffic does SH 55 over Big Creek carry?

About 4,100 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is SH 55 over Big Creek?

The structure is 53 ft (16.2 m) long with a longest span of 51 ft (15.5 m) and a deck 39 ft wide.

Who owns SH 55 over Big Creek?

It is owned by the State Highway Agency.