US Bridges

Siskiyou Ave over Interstate 5

Fair

Siskiyou County, California · 02-SIS-005-2.92-DMR · Structure no. 02 0097

Built
1966
59 years old
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
250 ft
4 main spans
Daily traffic
1,400
2024 count
Owner
State
State Highway Agency

About this bridge

Siskiyou Ave over Interstate 5 is a steel stringer/multi-beam or girder carrying Siskiyou Ave over Interstate 5 in Siskiyou County, California. It was built in 1966, so it is 59 years old, older than the California average of 54.8 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 1,400 vehicles a day, roughly 15% of them trucks, projected to reach 4,606 by 2045. The structure is 250 ft (76.1 m) long and 37 ft wide. If it were closed, the detour would be 11.8 mi (19 km).

Location

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CarriesSiskiyou Ave
CrossesInterstate 5
Location02-SIS-005-2.92-DMR
RouteCity Street 0
CountySiskiyou County
StateCalifornia
Coordinates41.22335, -122.27615
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.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment6: Equal to present minimum criteria
Operating rating74.3 US tons
Inventory rating44.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length250 ft (76.1 m)
Longest span90 ft (27.4 m)
Deck width37 ft (11.3 m)
Roadway width30 ft (9.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,400 (2024)
Projected traffic4,606 by 2045
Trucks15%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed11.8 mi (19 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Siskiyou Ave over Interstate 5 built?

It was built in 1966, making it 59 years old in 2025.

What condition is Siskiyou Ave over Interstate 5 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 Siskiyou Ave over Interstate 5 carry?

About 1,400 vehicles per day (2024 count), of which roughly 15% are trucks.

How long is Siskiyou Ave over Interstate 5?

The structure is 250 ft (76.1 m) long with a longest span of 90 ft (27.4 m) and a deck 37 ft wide.

Who owns Siskiyou Ave over Interstate 5?

It is owned by the State Highway Agency.