US Bridges

State Route 166 over Cuyama River

Fair

San Luis Obispo County, California · 05-SLO-166-22.86 · Structure no. 49 0180

Built
1959
66 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
306 ft
5 main spans
Daily traffic
2,600
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 166 over Cuyama River is a steel stringer/multi-beam or girder carrying State Route 166 over Cuyama River in San Luis Obispo County, California. It was built in 1959, so it is 66 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 5 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 2,600 vehicles a day, roughly 24% of them trucks, projected to reach 9,121 by 2042. The structure is 306 ft (93.3 m) long and 33 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesState Route 166
CrossesCuyama River
Location05-SLO-166-22.86
RouteState Highway 166
CountySan Luis Obispo County
StateCalifornia
Coordinates35.02202, -120.22856
Functional classRural 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating81 US tons
Inventory rating48.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length306 ft (93.3 m)
Longest span60 ft (18.3 m)
Deck width33 ft (10.2 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,600 (2009)
Projected traffic9,121 by 2042
Trucks24%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was State Route 166 over Cuyama River built?

It was built in 1959, making it 66 years old in 2025.

What condition is State Route 166 over Cuyama 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 May 2024.

How much traffic does State Route 166 over Cuyama River carry?

About 2,600 vehicles per day (2009 count), of which roughly 24% are trucks.

How long is State Route 166 over Cuyama River?

The structure is 306 ft (93.3 m) long with a longest span of 60 ft (18.3 m) and a deck 33 ft wide.

Who owns State Route 166 over Cuyama River?

It is owned by the State Highway Agency.