US Bridges

State Route 128 over Flynn Creek

Good

Mendocino County, California · 01-MEN-128-11.63 · Structure no. 10 0079

Built
1955
70 years old, rebuilt 1990
Condition
Good
inspected May 2023
Type
Slab
Concrete
Length
51 ft
1 main span
Daily traffic
3,300
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 128 over Flynn Creek is a concrete slab carrying State Route 128 over Flynn Creek in Mendocino County, California. It was built in 1955 and reconstructed in 1990, so it is 70 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 3,300 vehicles a day, roughly 15% of them trucks, projected to reach 4,700 by 2043. The structure is 51 ft (15.5 m) long and 35 ft wide. If it were closed, the detour would be 19.3 mi (31 km).

CarriesState Route 128
CrossesFlynn Creek
Location01-MEN-128-11.63
RouteState Highway 128
Coordinates39.16107, -123.58349
Functional classRural Minor Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
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 rating108.2 US tons
Inventory rating65 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length51 ft (15.5 m)
Longest span46 ft (14.1 m)
Deck width35 ft (10.8 m)
Roadway width32 ft (9.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,300 (2009)
Projected traffic4,700 by 2043
Trucks15%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed19.3 mi (31 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was State Route 128 over Flynn Creek built?

It was built in 1955, making it 70 years old in 2025. It was reconstructed in 1990.

What condition is State Route 128 over Flynn Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in May 2023.

How much traffic does State Route 128 over Flynn Creek carry?

About 3,300 vehicles per day (2009 count), of which roughly 15% are trucks.

How long is State Route 128 over Flynn Creek?

The structure is 51 ft (15.5 m) long with a longest span of 46 ft (14.1 m) and a deck 35 ft wide.

Who owns State Route 128 over Flynn Creek?

It is owned by the State Highway Agency.