US Bridges

SH 75 over Salmon River

Fair

Custer County, Idaho · 5.0 S. Stanley · Structure no. 000000000017760

Built
1985
40 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
154 ft
2 main spans
Daily traffic
800
2023 count
Owner
State
State Highway Agency

About this bridge

SH 75 over Salmon River is a prestressed concrete continuous stringer/multi-beam or girder carrying SH 75 over Salmon River in Custer County, Idaho. It was built in 1985, so it is 40 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 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 800 vehicles a day, roughly 16% of them trucks, projected to reach 1,200 by 2042. The structure is 154 ft (46.9 m) long and 40 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSH 75
CrossesSalmon River
Location5.0 S. Stanley
RouteState Highway 75
CountyCuster County
StateIdaho
Coordinates44.16319, -114.88625
Functional classRural Minor Arterial

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating92 US tons
Inventory rating55 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 25 or greater
Structure length154 ft (46.9 m)
Longest span74 ft (22.6 m)
Deck width40 ft (12.2 m)
Roadway width37 ft (11.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic800 (2023)
Projected traffic1,200 by 2042
Trucks16%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

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$1.7 million (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 75 over Salmon River built?

It was built in 1985, making it 40 years old in 2025.

What condition is SH 75 over Salmon River 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 July 2024.

How much traffic does SH 75 over Salmon River carry?

About 800 vehicles per day (2023 count), of which roughly 16% are trucks.

How long is SH 75 over Salmon River?

The structure is 154 ft (46.9 m) long with a longest span of 74 ft (22.6 m) and a deck 40 ft wide.

Who owns SH 75 over Salmon River?

It is owned by the State Highway Agency.