US Bridges

ST Charles Avenue over Interstate 280

Fair

San Mateo County, California · 04-SM-280-M27.41L-DLC · Structure no. 35 0176

Built
1965
60 years old
Condition
Fair
inspected February 2025
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
274 ft
4 main spans
Daily traffic
15,000
2004 count
Owner
State
State Highway Agency

About this bridge

ST Charles Avenue over Interstate 280 is a concrete continuous box beam or girders - multiple carrying ST Charles Avenue over Interstate 280 in San Mateo County, California. It was built in 1965, so it is 60 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 15,000 vehicles a day, roughly 2% of them trucks, projected to reach 20,157 by 2047. The structure is 274 ft (83.5 m) long and 39 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesST Charles Avenue
CrossesInterstate 280
Location04-SM-280-M27.41L-DLC
RouteCity Street 0
CountySan Mateo County
StateCalifornia
Coordinates37.70838, -122.46928
Functional classUrban Principal Arterial - Interstate

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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment6: Equal to present minimum criteria
Operating rating56.1 US tons
Inventory rating43.2 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length274 ft (83.5 m)
Longest span89 ft (27.1 m)
Deck width39 ft (12 m)
Roadway width28 ft (8.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,000 (2004)
Projected traffic20,157 by 2047
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesHighway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemYes

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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was ST Charles Avenue over Interstate 280 built?

It was built in 1965, making it 60 years old in 2025.

What condition is ST Charles Avenue over Interstate 280 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 February 2025.

How much traffic does ST Charles Avenue over Interstate 280 carry?

About 15,000 vehicles per day (2004 count), of which roughly 2% are trucks.

How long is ST Charles Avenue over Interstate 280?

The structure is 274 ft (83.5 m) long with a longest span of 89 ft (27.1 m) and a deck 39 ft wide.

Who owns ST Charles Avenue over Interstate 280?

It is owned by the State Highway Agency.