US Bridges

Stilson Road over Farmers Union Canal

Fair

Ada County, Idaho · In Boise;stilson Rd. · Structure no. 000000000026325

Built
1979
46 years old
Condition
Fair
inspected March 2021
Type
Tee Beam
Prestressed Concrete
Length
22 ft
1 main span
Daily traffic
500
2023 count
Owner
County
County Highway Agency

About this bridge

Stilson Road over Farmers Union Canal is a prestressed concrete tee beam carrying Stilson Road over Farmers Union Canal in Ada County, Idaho. It was built in 1979, so it is 46 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 500 vehicles a day, roughly 10% of them trucks, projected to reach 750 by 2039. The structure is 22 ft (6.7 m) long and 36 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

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CarriesStilson Road
CrossesFarmers Union Canal
LocationIn Boise;stilson Rd.
RouteCity Street 0
CountyAda County
StateIdaho
Coordinates43.63693, -116.23968
Functional classUrban 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMarch 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.5 US tons
Inventory rating41.7 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length22 ft (6.7 m)
Longest span21 ft (6.4 m)
Deck width36 ft (11 m)
Roadway width29 ft (8.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic500 (2023)
Projected traffic750 by 2039
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Stilson Road over Farmers Union Canal built?

It was built in 1979, making it 46 years old in 2025.

What condition is Stilson Road over Farmers Union Canal 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 March 2021.

How much traffic does Stilson Road over Farmers Union Canal carry?

About 500 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is Stilson Road over Farmers Union Canal?

The structure is 22 ft (6.7 m) long with a longest span of 21 ft (6.4 m) and a deck 36 ft wide.

Who owns Stilson Road over Farmers Union Canal?

It is owned by the County Highway Agency.