US Bridges

SH 55 over Boulder Creek

Fair

Valley County, Idaho · At Donnelly Scl · Structure no. 000000000014851

Built
1999
26 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
57 ft
1 main span
Daily traffic
6,000
2023 count
Owner
State
State Highway Agency

About this bridge

SH 55 over Boulder Creek is a prestressed concrete stringer/multi-beam or girder carrying SH 55 over Boulder Creek in Valley County, Idaho. It was built in 1999, so it is 26 years old, younger 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 6,000 vehicles a day, roughly 15% of them trucks, projected to reach 9,000 by 2042. The structure is 57 ft (17.4 m) long and 43 ft wide. If it were closed, the detour would be 5 mi (8 km).

Location

Open in Google Maps
CarriesSH 55
CrossesBoulder Creek
LocationAt Donnelly Scl
RouteState Highway 55
CountyValley County
StateIdaho
Coordinates44.72692, -116.07436
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.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMay 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating78 US tons
Inventory rating47 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length57 ft (17.4 m)
Longest span55 ft (16.8 m)
Deck width43 ft (13 m)
Roadway width35 ft (10.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,000 (2023)
Projected traffic9,000 by 2042
Trucks15%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed5 mi (8 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 SH 55 over Boulder Creek built?

It was built in 1999, making it 26 years old in 2025.

What condition is SH 55 over Boulder 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 May 2024.

How much traffic does SH 55 over Boulder Creek carry?

About 6,000 vehicles per day (2023 count), of which roughly 15% are trucks.

How long is SH 55 over Boulder Creek?

The structure is 57 ft (17.4 m) long with a longest span of 55 ft (16.8 m) and a deck 43 ft wide.

Who owns SH 55 over Boulder Creek?

It is owned by the State Highway Agency.