US Bridges

Alderpoint RD over Conley Creek

Fair

Humboldt County, California · 1 MI S of Blocksburg · Structure no. 04C0165

Built
1990
35 years old
Condition
Fair
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
70 ft
1 main span
Daily traffic
114
2008 count
Owner
County
County Highway Agency

About this bridge

Alderpoint RD over Conley Creek is a steel stringer/multi-beam or girder carrying Alderpoint RD over Conley Creek in Humboldt County, California. It was built in 1990, so it is 35 years old, younger 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 114 vehicles a day, roughly 5% of them trucks, projected to reach 327 by 2042. The structure is 70 ft (21.3 m) long and 26 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesAlderpoint RD
CrossesConley Creek
Location1 MI S of Blocksburg
RouteCounty Highway 0
CountyHumboldt County
StateCalifornia
Coordinates40.27345, -123.62491
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionFebruary 2024
Inspection intervalevery 12 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating36.8 US tons
Inventory rating22.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckSteel plate
Main spans1
Design loadUnknown
Structure length70 ft (21.3 m)
Longest span65 ft (19.8 m)
Deck width26 ft (8 m)
Roadway width25 ft (7.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic114 (2008)
Projected traffic327 by 2042
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

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 Alderpoint RD over Conley Creek built?

It was built in 1990, making it 35 years old in 2025.

What condition is Alderpoint RD over Conley 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 February 2024.

How much traffic does Alderpoint RD over Conley Creek carry?

About 114 vehicles per day (2008 count), of which roughly 5% are trucks.

How long is Alderpoint RD over Conley Creek?

The structure is 70 ft (21.3 m) long with a longest span of 65 ft (19.8 m) and a deck 26 ft wide.

Who owns Alderpoint RD over Conley Creek?

It is owned by the County Highway Agency.