US Bridges

I 86 Wbl over Rock Cr;massacre Rock Br

Fair

Power County, Idaho · 12.1 W. American Falls · Structure no. 000000000010710

Built
1963
62 years old, rebuilt 1985
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
169 ft
3 main spans
Daily traffic
4,150
2023 count
Owner
State
State Highway Agency

About this bridge

I 86 Wbl over Rock Cr;massacre Rock Br is a prestressed concrete stringer/multi-beam or girder carrying I 86 Wbl over Rock Cr;massacre Rock Br in Power County, Idaho. It was built in 1963 and reconstructed in 1985, so it is 62 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 5 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 4,150 vehicles a day, roughly 26% of them trucks, projected to reach 6,225 by 2042. The structure is 169 ft (51.5 m) long and 41 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 86 Wbl
CrossesRock Cr;massacre Rock Br
Location12.1 W. American Falls
RouteInterstate 86
CountyPower County
StateIdaho
Coordinates42.6525, -113.01408
Functional classRural Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating72 US tons
Inventory rating41 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length169 ft (51.5 m)
Longest span56 ft (17.1 m)
Deck width41 ft (12.4 m)
Roadway width38 ft (11.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,150 (2023)
Projected traffic6,225 by 2042
Trucks26%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

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 I 86 Wbl over Rock Cr;massacre Rock Br built?

It was built in 1963, making it 62 years old in 2025. It was reconstructed in 1985.

What condition is I 86 Wbl over Rock Cr;massacre Rock Br 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 I 86 Wbl over Rock Cr;massacre Rock Br carry?

About 4,150 vehicles per day (2023 count), of which roughly 26% are trucks.

How long is I 86 Wbl over Rock Cr;massacre Rock Br?

The structure is 169 ft (51.5 m) long with a longest span of 56 ft (17.1 m) and a deck 41 ft wide.

Who owns I 86 Wbl over Rock Cr;massacre Rock Br?

It is owned by the State Highway Agency.