US Bridges

Forest Road 900 over North Fork Big River

Fair

Mendocino County, California · 0.16 MI S JCT SR 20 · Structure no. 10F0053

Built
1982
43 years old
Condition
Fair
inspected May 2023
Type
Arch - Deck
Aluminum, Wrought Iron, or Cast Iron
Length
29 ft
1 main span
Daily traffic
25
2009 count
Owner
State
State Park, Forest, or Reservation Agency

About this bridge

Forest Road 900 over North Fork Big River is a aluminum, wrought iron, or cast iron arch - deck carrying Forest Road 900 over North Fork Big River in Mendocino County, California. It was built in 1982, so it is 43 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 25 vehicles a day, projected to reach 32 by 2041. The structure is 29 ft (8.8 m) long. If it were closed, the detour would be 9.9 mi (16 km).

Location

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CarriesForest Road 900
CrossesNorth Fork Big River
Location0.16 MI S JCT SR 20
RouteState Lands Road 0
CountyMendocino County
StateCalifornia
Coordinates39.34603, -123.51011
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
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 protection8 Very GoodNo problems noted.
Last inspectionMay 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
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeArch - Deck
MaterialAluminum, Wrought Iron, or Cast Iron
DeckNot applicable
Main spans1
Design loadUnknown
Structure length29 ft (8.8 m)
Longest span29 ft (8.8 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic25 (2009)
Projected traffic32 by 2041
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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 statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Forest Road 900 over North Fork Big River built?

It was built in 1982, making it 43 years old in 2025.

What condition is Forest Road 900 over North Fork Big River 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 May 2023.

How much traffic does Forest Road 900 over North Fork Big River carry?

About 25 vehicles per day (2009 count).

How long is Forest Road 900 over North Fork Big River?

The structure is 29 ft (8.8 m) long with a longest span of 29 ft (8.8 m).

Who owns Forest Road 900 over North Fork Big River?

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