US Bridges

Trancas ST over Napa River

Fair

Napa County, California · 1.3 MI E SR 29 · Structure no. 21C0003

Built
1960
65 years old
Condition
Fair
inspected August 2023
Type
Tee Beam
Concrete Continuous
Length
342 ft
3 main spans
Daily traffic
14,755
2017 count
Owner
City
City or Municipal Highway Agency

About this bridge

Trancas ST over Napa River is a concrete continuous tee beam carrying Trancas ST over Napa River in Napa County, California. It was built in 1960, so it is 65 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 6 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 14,755 vehicles a day, roughly 2% of them trucks, projected to reach 35,863 by 2041. The structure is 342 ft (104.2 m) long and 65 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesTrancas ST
CrossesNapa River
Location1.3 MI E SR 29
RouteCity Street 0
CountyNapa County
StateCalifornia
Coordinates38.32482, -122.28444
Functional classUrban Other Principal 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating33.6 US tons
Inventory rating25.7 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3 (+4 approach)
Design loadHS 20
Structure length342 ft (104.2 m)
Longest span76 ft (23.1 m)
Deck width65 ft (19.7 m)
Roadway width64 ft (19.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic14,755 (2017)
Projected traffic35,863 by 2041
Trucks2%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal 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 Trancas ST over Napa River built?

It was built in 1960, making it 65 years old in 2025.

What condition is Trancas ST 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 August 2023.

How much traffic does Trancas ST over Napa River carry?

About 14,755 vehicles per day (2017 count), of which roughly 2% are trucks.

How long is Trancas ST over Napa River?

The structure is 342 ft (104.2 m) long with a longest span of 76 ft (23.1 m) and a deck 65 ft wide.

Who owns Trancas ST over Napa River?

It is owned by the City or Municipal Highway Agency.