US Bridges

White Rock Road over Mariposa Creek

Fair

Mariposa County, California · 1.6 MI S/O Old HWY · Structure no. 40C0032

Built
1968
57 years old
Condition
Fair
inspected September 2023
Type
Girder and Floorbeam System
Steel
Length
72 ft
1 main span
Daily traffic
20
2005 count
Owner
County
County Highway Agency

About this bridge

White Rock Road over Mariposa Creek is a steel girder and floorbeam system carrying White Rock Road over Mariposa Creek in Mariposa County, California. It was built in 1968, so it is 57 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 20 vehicles a day, projected to reach 51 by 2040. The structure is 72 ft (22 m) long and 16 ft wide. If it were closed, the detour would be 11.8 mi (19 km).

Location

Open in Google Maps
CarriesWhite Rock Road
CrossesMariposa Creek
Location1.6 MI S/O Old HWY
RouteCounty Highway 0
CountyMariposa County
StateCalifornia
Coordinates37.39894, -120.00369
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
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.
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 inspectionSeptember 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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating30 US tons
Inventory rating17.9 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+1 approach)
Design loadUnknown
Structure length72 ft (22 m)
Longest span50 ft (15.2 m)
Deck width16 ft (4.9 m)
Roadway width14 ft (4.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2005)
Projected traffic51 by 2040
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed11.8 mi (19 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 White Rock Road over Mariposa Creek built?

It was built in 1968, making it 57 years old in 2025.

What condition is White Rock Road over Mariposa 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 September 2023.

How much traffic does White Rock Road over Mariposa Creek carry?

About 20 vehicles per day (2005 count).

How long is White Rock Road over Mariposa Creek?

The structure is 72 ft (22 m) long with a longest span of 50 ft (15.2 m) and a deck 16 ft wide.

Who owns White Rock Road over Mariposa Creek?

It is owned by the County Highway Agency.