US Bridges

Porter Creek Road over Porter Creek

Fair

Sonoma County, California · 24.3 MI Beging RTE 786 · Structure no. 20C0119

Built
1960
65 years old
Condition
Fair
inspected October 2023
Type
Culvert
Concrete Continuous
Length
44 ft
2 main spans
Daily traffic
5,800
2015 count
Owner
County
County Highway Agency

About this bridge

Porter Creek Road over Porter Creek is a concrete continuous culvert carrying Porter Creek Road over Porter Creek in Sonoma County, California. It was built in 1960, so it is 65 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 5,800 vehicles a day, roughly 5% of them trucks, projected to reach 7,625 by 2041. The structure is 44 ft (13.4 m) long. If it were closed, the detour would be 9.9 mi (16 km).

Location

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CarriesPorter Creek Road
CrossesPorter Creek
Location24.3 MI Beging RTE 786
RouteCounty Highway 0
CountySonoma County
StateCalifornia
Coordinates38.54942, -122.66939
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
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44.6 US tons
Inventory rating26.8 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadHS 20
Structure length44 ft (13.4 m)
Longest span22 ft (6.6 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,800 (2015)
Projected traffic7,625 by 2041
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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 Porter Creek Road over Porter Creek built?

It was built in 1960, making it 65 years old in 2025.

What condition is Porter Creek Road over Porter Creek 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 Porter Creek Road over Porter Creek carry?

About 5,800 vehicles per day (2015 count), of which roughly 5% are trucks.

How long is Porter Creek Road over Porter Creek?

The structure is 44 ft (13.4 m) long with a longest span of 22 ft (6.6 m).

Who owns Porter Creek Road over Porter Creek?

It is owned by the County Highway Agency.