US Bridges

SH 75 over Salmon River

Fair

Blaine County, Idaho · 1.5 SE Sawtooth City · Structure no. 000000000017710

Built
1977
48 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
45 ft
1 main span
Daily traffic
1,000
2023 count
Owner
State
State Highway Agency

About this bridge

SH 75 over Salmon River is a prestressed concrete stringer/multi-beam or girder carrying SH 75 over Salmon River in Blaine County, Idaho. It was built in 1977, so it is 48 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 1,000 vehicles a day, roughly 11% of them trucks, projected to reach 1,500 by 2042. The structure is 45 ft (13.7 m) long and 41 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSH 75
CrossesSalmon River
Location1.5 SE Sawtooth City
RouteState Highway 75
CountyBlaine County
StateIdaho
Coordinates43.88411, -114.76394
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure8 Very GoodNo problems noted.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating57 US tons
Inventory rating29 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length45 ft (13.7 m)
Longest span44 ft (13.4 m)
Deck width41 ft (12.6 m)
Roadway width38 ft (11.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,000 (2023)
Projected traffic1,500 by 2042
Trucks11%
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$653,000 (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 75 over Salmon River built?

It was built in 1977, making it 48 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 1,000 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is SH 75 over Salmon River?

The structure is 45 ft (13.7 m) long with a longest span of 44 ft (13.4 m) and a deck 41 ft wide.

Who owns SH 75 over Salmon River?

It is owned by the State Highway Agency.