US Bridges

State Route 255 over Samoa Channel

Fair

Humboldt County, California · 01-HUM-255-1.37-EUR · Structure no. 04 0228

Built
1971
54 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
2,507 ft
20 main spans
Daily traffic
7,300
2010 count
Owner
State
State Highway Agency

About this bridge

State Route 255 over Samoa Channel is a prestressed concrete continuous stringer/multi-beam or girder carrying State Route 255 over Samoa Channel in Humboldt County, California. It was built in 1971, so it is 54 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 7,300 vehicles a day, roughly 9% of them trucks, projected to reach 8,941 by 2041. The structure is 2,507 ft (764 m) long and 34 ft wide. If it were closed, the detour would be 13 mi (21 km).

Location

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CarriesState Route 255
CrossesSamoa Channel
Location01-HUM-255-1.37-EUR
RouteState Highway 255
CountyHumboldt County
StateCalifornia
Coordinates40.8199, -124.16726
Functional classUrban 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
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 protection8 Very GoodNo problems noted.
Last inspectionSeptember 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 rating42.9 US tons
Inventory rating22.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans20
Design loadHS 20
Structure length2,507 ft (764 m)
Longest span225 ft (68.6 m)
Deck width34 ft (10.4 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,300 (2010)
Projected traffic8,941 by 2041
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway, waterway and railroad
Detour if closed13 mi (21 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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was State Route 255 over Samoa Channel built?

It was built in 1971, making it 54 years old in 2025.

What condition is State Route 255 over Samoa Channel 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 September 2023.

How much traffic does State Route 255 over Samoa Channel carry?

About 7,300 vehicles per day (2010 count), of which roughly 9% are trucks.

How long is State Route 255 over Samoa Channel?

The structure is 2,507 ft (764 m) long with a longest span of 225 ft (68.6 m) and a deck 34 ft wide.

Who owns State Route 255 over Samoa Channel?

It is owned by the State Highway Agency.