US Bridges

Llano RD over Laguna De Santa Rosa

Fair

Sonoma County, California · 0.5 MI N of ST HWY 116 · Structure no. 20C0233

Built
1962
63 years old
Condition
Fair
inspected May 2023
Type
Slab
Concrete Continuous
Length
179 ft
6 main spans
Daily traffic
2,500
2015 count
Owner
County
County Highway Agency

About this bridge

Llano RD over Laguna De Santa Rosa is a concrete continuous slab carrying Llano RD over Laguna De Santa Rosa in Sonoma County, California. It was built in 1962, so it is 63 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 2,500 vehicles a day, roughly 5% of them trucks, projected to reach 3,000 by 2040. The structure is 179 ft (54.6 m) long and 32 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesLlano RD
CrossesLaguna De Santa Rosa
Location0.5 MI N of ST HWY 116
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.36567, -122.7688
Functional classRural Major Collector

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59.6 US tons
Inventory rating36 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans6
Design loadUnknown
Structure length179 ft (54.6 m)
Longest span32 ft (9.8 m)
Deck width32 ft (9.9 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,500 (2015)
Projected traffic3,000 by 2040
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Llano RD over Laguna De Santa Rosa built?

It was built in 1962, making it 63 years old in 2025.

What condition is Llano RD over Laguna De Santa Rosa 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 2023.

How much traffic does Llano RD over Laguna De Santa Rosa carry?

About 2,500 vehicles per day (2015 count), of which roughly 5% are trucks.

How long is Llano RD over Laguna De Santa Rosa?

The structure is 179 ft (54.6 m) long with a longest span of 32 ft (9.8 m) and a deck 32 ft wide.

Who owns Llano RD over Laguna De Santa Rosa?

It is owned by the County Highway Agency.