US Bridges

Chalk Hill RD over Brooks Creek

Fair

Sonoma County, California · 4.5 MI S of SR 128 · Structure no. 20C0330

Built
1956
69 years old
Condition
Fair
inspected July 2023
Type
Slab
Concrete
Length
53 ft
2 main spans
Daily traffic
850
2015 count
Owner
County
County Highway Agency

About this bridge

Chalk Hill RD over Brooks Creek is a concrete slab carrying Chalk Hill RD over Brooks Creek in Sonoma County, California. It was built in 1956, so it is 69 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 850 vehicles a day, roughly 1% of them trucks, projected to reach 1,000 by 2040. The structure is 53 ft (16.2 m) long and 29 ft wide. If it were closed, the detour would be 21.7 mi (35 km).

CarriesChalk Hill RD
CrossesBrooks Creek
Location4.5 MI S of SR 128
RouteCounty Highway 0
Coordinates38.60027, -122.77762
Functional classRural Minor 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.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating40.3 US tons
Inventory rating24.3 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans2
Design loadUnknown
Structure length53 ft (16.2 m)
Longest span26 ft (7.9 m)
Deck width29 ft (8.7 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic850 (2015)
Projected traffic1,000 by 2040
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed21.7 mi (35 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 Chalk Hill RD over Brooks Creek built?

It was built in 1956, making it 69 years old in 2025.

What condition is Chalk Hill RD over Brooks 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 July 2023.

How much traffic does Chalk Hill RD over Brooks Creek carry?

About 850 vehicles per day (2015 count), of which roughly 1% are trucks.

How long is Chalk Hill RD over Brooks Creek?

The structure is 53 ft (16.2 m) long with a longest span of 26 ft (7.9 m) and a deck 29 ft wide.

Who owns Chalk Hill RD over Brooks Creek?

It is owned by the County Highway Agency.