US Bridges

State Route 128 over Napa River

Fair

Napa County, California · 04-NAP-128-5.25 · Structure no. 21 0020

Built
1981
44 years old
Condition
Fair
inspected April 2024
Type
Box Beam or Girders - Multiple
Prestressed Concrete Continuous
Length
130 ft
2 main spans
Daily traffic
2,075
2009 count
Owner
State
State Highway Agency

About this bridge

State Route 128 over Napa River is a prestressed concrete continuous box beam or girders - multiple carrying State Route 128 over Napa River in Napa County, California. It was built in 1981, so it is 44 years old, younger 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 2,075 vehicles a day, roughly 5% of them trucks, projected to reach 3,363 by 2042. The structure is 130 ft (39.6 m) long and 36 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesState Route 128
CrossesNapa River
Location04-NAP-128-5.25
RouteState Highway 128
CountyNapa County
StateCalifornia
Coordinates38.46449, -122.41233
Functional classRural Major 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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating59.6 US tons
Inventory rating35.7 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20 + Mod
Structure length130 ft (39.6 m)
Longest span65 ft (19.8 m)
Deck width36 ft (10.9 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,075 (2009)
Projected traffic3,363 by 2042
Trucks5%
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

OwnerState Highway Agency
Maintained byState 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 State Route 128 over Napa River built?

It was built in 1981, making it 44 years old in 2025.

What condition is State Route 128 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 April 2024.

How much traffic does State Route 128 over Napa River carry?

About 2,075 vehicles per day (2009 count), of which roughly 5% are trucks.

How long is State Route 128 over Napa River?

The structure is 130 ft (39.6 m) long with a longest span of 65 ft (19.8 m) and a deck 36 ft wide.

Who owns State Route 128 over Napa River?

It is owned by the State Highway Agency.