US Bridges

SH 55 over S.Fk.Payette River

Fair

Boise County, Idaho · At Banks · Structure no. 000000000014790

Built
1955
70 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Concrete
Length
275 ft
3 main spans
Daily traffic
7,300
2023 count
Owner
State
State Highway Agency

About this bridge

SH 55 over S.Fk.Payette River is a concrete stringer/multi-beam or girder carrying SH 55 over S.Fk.Payette River in Boise County, Idaho. It was built in 1955, so it is 70 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 7,300 vehicles a day, roughly 2% of them trucks, projected to reach 10,950 by 2042. The structure is 275 ft (83.8 m) long and 38 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSH 55
CrossesS.Fk.Payette River
LocationAt Banks
RouteState Highway 55
CountyBoise County
StateIdaho
Coordinates44.08395, -116.11557
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.
Superstructure7 GoodSome minor problems.
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
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation7: Better than present minimum 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 rating68 US tons
Inventory rating40 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length275 ft (83.8 m)
Longest span110 ft (33.5 m)
Deck width38 ft (11.5 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,300 (2023)
Projected traffic10,950 by 2042
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed98.8 mi (159 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$4.8 million (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SH 55 over S.Fk.Payette River built?

It was built in 1955, making it 70 years old in 2025.

What condition is SH 55 over S.Fk.Payette 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 September 2024.

How much traffic does SH 55 over S.Fk.Payette River carry?

About 7,300 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is SH 55 over S.Fk.Payette River?

The structure is 275 ft (83.8 m) long with a longest span of 110 ft (33.5 m) and a deck 38 ft wide.

Who owns SH 55 over S.Fk.Payette River?

It is owned by the State Highway Agency.