US Bridges

State Park Road over Upper Durphy Creek

Fair

Humboldt County, California · Richardson Grove St. Pk. · Structure no. 04P0002

Built
1965
60 years old
Condition
Fair
inspected July 2023
Type
Culvert
Steel
Length
23 ft
3 main spans
Daily traffic
300
1982 count
Owner
State
State Park, Forest, or Reservation Agency

About this bridge

State Park Road over Upper Durphy Creek is a steel culvert carrying State Park Road over Upper Durphy Creek in Humboldt County, California. It was built in 1965, so it is 60 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 300 vehicles a day, roughly 5% of them trucks, projected to reach 1,073 by 2041. The structure is 23 ft (7.1 m) long and 32 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesState Park Road
CrossesUpper Durphy Creek
LocationRichardson Grove St. Pk.
RouteState Lands Road 0
CountyHumboldt County
StateCalifornia
Coordinates40.02062, -123.79407
Functional classRural Local

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.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating44.6 US tons
Inventory rating26.8 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans3
Design loadUnknown
Structure length23 ft (7.1 m)
Longest span10 ft (3.2 m)
Deck width32 ft (9.9 m)
Roadway width21 ft (6.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic300 (1982)
Projected traffic1,073 by 2041
Trucks5%
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 Park, Forest, or Reservation Agency
Maintained byState Park, Forest, or Reservation 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 Park Road over Upper Durphy Creek built?

It was built in 1965, making it 60 years old in 2025.

What condition is State Park Road over Upper Durphy 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 July 2023.

How much traffic does State Park Road over Upper Durphy Creek carry?

About 300 vehicles per day (1982 count), of which roughly 5% are trucks.

How long is State Park Road over Upper Durphy Creek?

The structure is 23 ft (7.1 m) long with a longest span of 10 ft (3.2 m) and a deck 32 ft wide.

Who owns State Park Road over Upper Durphy Creek?

It is owned by the State Park, Forest, or Reservation Agency.