US Bridges

Thomas Road over Salmon Creek

Fair

Humboldt County, California · 3.24 MI S Salmon Ck RD · Structure no. 04C0151

Built
1962
63 years old
Condition
Fair
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
185 ft
2 main spans
Daily traffic
395
2011 count
Owner
County
County Highway Agency

About this bridge

Thomas Road over Salmon Creek is a steel stringer/multi-beam or girder carrying Thomas Road over Salmon Creek in Humboldt 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 395 vehicles a day, roughly 1% of them trucks, projected to reach 327 by 2042. The structure is 185 ft (56.4 m) long and 16 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesThomas Road
CrossesSalmon Creek
Location3.24 MI S Salmon Ck RD
RouteCounty Highway 0
CountyHumboldt County
StateCalifornia
Coordinates40.21016, -123.89413
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionFebruary 2024
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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment4: Meets minimum tolerable limits to be left in place as is
Operating rating94.7 US tons
Inventory rating56.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans2
Design loadH 20
Structure length185 ft (56.4 m)
Longest span90 ft (27.4 m)
Deck width16 ft (5 m)
Roadway width16 ft (4.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic395 (2011)
Projected traffic327 by 2042
Trucks1%
Lanes on structure1
Traffic directionOne-lane bridge for two-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 Thomas Road over Salmon Creek built?

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

What condition is Thomas Road over Salmon 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 Thomas Road over Salmon Creek carry?

About 395 vehicles per day (2011 count), of which roughly 1% are trucks.

How long is Thomas Road over Salmon Creek?

The structure is 185 ft (56.4 m) long with a longest span of 90 ft (27.4 m) and a deck 16 ft wide.

Who owns Thomas Road over Salmon Creek?

It is owned by the County Highway Agency.