US Bridges

STC3787;SWAN Falls over Mora Canal

Fair

Ada County, Idaho · 1.4 S. 0.3 E. Kuna · Structure no. 000000000026245

Built
1981
44 years old
Condition
Fair
inspected October 2023
Type
Tee Beam
Prestressed Concrete
Length
70 ft
2 main spans
Daily traffic
1,600
2023 count
Owner
County
County Highway Agency

About this bridge

STC3787;SWAN Falls over Mora Canal is a prestressed concrete tee beam carrying STC3787;SWAN Falls over Mora Canal in Ada County, Idaho. It was built in 1981, so it is 44 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 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 1,600 vehicles a day, projected to reach 2,400 by 2042. The structure is 70 ft (21.3 m) long and 32 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesSTC3787;SWAN Falls
CrossesMora Canal
Location1.4 S. 0.3 E. Kuna
RouteCounty Highway 3787
CountyAda County
StateIdaho
Coordinates43.47083, -116.41367
Functional classUrban 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
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 rating38 US tons
Inventory rating23 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length70 ft (21.3 m)
Longest span35 ft (10.7 m)
Deck width32 ft (9.8 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,600 (2023)
Projected traffic2,400 by 2042
Trucks0%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$941,000 (2021 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was STC3787;SWAN Falls over Mora Canal built?

It was built in 1981, making it 44 years old in 2025.

What condition is STC3787;SWAN Falls over Mora 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 October 2023.

How much traffic does STC3787;SWAN Falls over Mora Canal carry?

About 1,600 vehicles per day (2023 count).

How long is STC3787;SWAN Falls over Mora Canal?

The structure is 70 ft (21.3 m) long with a longest span of 35 ft (10.7 m) and a deck 32 ft wide.

Who owns STC3787;SWAN Falls over Mora Canal?

It is owned by the County Highway Agency.