US Bridges

N.Fk. Boise R. Rd. over North Fork Boise River

Fair

Boise County, Idaho · (deer Park Bridge) · Structure no. 040203000001170

Built
1949
76 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
133 ft
3 main spans
Daily traffic
59
1992 count
Owner
Federal
U.S. Forest Service

About this bridge

N.Fk. Boise R. Rd. over North Fork Boise River is a steel continuous stringer/multi-beam or girder carrying N.Fk. Boise R. Rd. over North Fork Boise River in Boise County, Idaho. It was built in 1949, so it is 76 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 59 vehicles a day, projected to reach 88 by 2045. The structure is 133 ft (40.6 m) long and 16 ft wide. If it were closed, the detour would be 36.7 mi (59 km).

Location

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CarriesN.Fk. Boise R. Rd.
CrossesNorth Fork Boise River
Location(deer Park Bridge)
RouteFederal Lands Road 327
CountyBoise County
StateIdaho
Coordinates43.91275, -115.40637
Functional classRural Local

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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating35.7 US tons
Inventory rating27.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckWood or timber
Main spans3
Design loadHS 20
Structure length133 ft (40.6 m)
Longest span50 ft (15.2 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic59 (1992)
Projected traffic88 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed36.7 mi (59 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was N.Fk. Boise R. Rd. over North Fork Boise River built?

It was built in 1949, making it 76 years old in 2025.

What condition is N.Fk. Boise R. Rd. over North Fork Boise 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 2023.

How much traffic does N.Fk. Boise R. Rd. over North Fork Boise River carry?

About 59 vehicles per day (1992 count).

How long is N.Fk. Boise R. Rd. over North Fork Boise River?

The structure is 133 ft (40.6 m) long with a longest span of 50 ft (15.2 m) and a deck 16 ft wide.

Who owns N.Fk. Boise R. Rd. over North Fork Boise River?

It is owned by the U.S. Forest Service.