US Bridges

Delta Road over Rock Slough

Good

Contra Costa County, California · 3 MI E Knightsen · Structure no. 28C0082

Built
2001
24 years old
Condition
Good
inspected July 2024
Type
Tee Beam
Prestressed Concrete
Length
177 ft
3 main spans
Daily traffic
532
2013 count
Owner
County
County Highway Agency

About this bridge

Delta Road over Rock Slough is a prestressed concrete tee beam carrying Delta Road over Rock Slough in Contra Costa County, California. It was built in 2001, so it is 24 years old, younger 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 532 vehicles a day, roughly 4% of them trucks, projected to reach 824 by 2046. The structure is 177 ft (54 m) long and 29 ft wide. If it were closed, the detour would be 12.4 mi (20 km).

Location

Open in Google Maps
CarriesDelta Road
CrossesRock Slough
Location3 MI E Knightsen
RouteCounty Highway 0
CountyContra Costa County
StateCalifornia
Coordinates37.97652, -121.62001
Functional classRural Major Collector

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.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection9 ExcellentNo problems noted.
Last inspectionJuly 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length177 ft (54 m)
Longest span59 ft (18 m)
Deck width29 ft (8.9 m)
Roadway width26 ft (8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic532 (2013)
Projected traffic824 by 2046
Trucks4%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed12.4 mi (20 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 Delta Road over Rock Slough built?

It was built in 2001, making it 24 years old in 2025.

What condition is Delta Road over Rock Slough 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 July 2024.

How much traffic does Delta Road over Rock Slough carry?

About 532 vehicles per day (2013 count), of which roughly 4% are trucks.

How long is Delta Road over Rock Slough?

The structure is 177 ft (54 m) long with a longest span of 59 ft (18 m) and a deck 29 ft wide.

Who owns Delta Road over Rock Slough?

It is owned by the County Highway Agency.