US Bridges

Pratt Avenue over Napa River

Fair

Napa County, California · 0.1 MI S Silverado Trail · Structure no. 21C0072

Built
1921
104 years old
Condition
Fair
inspected May 2023
Type
Girder and Floorbeam System
Concrete Continuous
Length
120 ft
2 main spans
Daily traffic
1,106
1978 count
Owner
County
County Highway Agency

About this bridge

Pratt Avenue over Napa River is a concrete continuous girder and floorbeam system carrying Pratt Avenue over Napa River in Napa County, California. It was built in 1921, so it is 104 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 1,106 vehicles a day, roughly 10% of them trucks, projected to reach 1,817 by 2040. The structure is 120 ft (36.6 m) long and 23 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesPratt Avenue
CrossesNapa River
Location0.1 MI S Silverado Trail
RouteCounty Highway 0
CountyNapa County
StateCalifornia
Coordinates38.52055, -122.47274
Functional classRural Minor Arterial

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.
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 geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating55 US tons
Inventory rating33.2 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadUnknown
Structure length120 ft (36.6 m)
Longest span57 ft (17.4 m)
Deck width23 ft (7 m)
Roadway width19 ft (5.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,106 (1978)
Projected traffic1,817 by 2040
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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 Pratt Avenue over Napa River built?

It was built in 1921, making it 104 years old in 2025.

What condition is Pratt Avenue over Napa 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 Pratt Avenue over Napa River carry?

About 1,106 vehicles per day (1978 count), of which roughly 10% are trucks.

How long is Pratt Avenue over Napa River?

The structure is 120 ft (36.6 m) long with a longest span of 57 ft (17.4 m) and a deck 23 ft wide.

Who owns Pratt Avenue over Napa River?

It is owned by the County Highway Agency.