US Bridges

Interstate 280 SB over Avalon Drive

Poor

San Mateo County, California · 04-SM-280-R22.04-SSF · Structure no. 35 0228L

Built
1971
54 years old
Condition
Poor
inspected February 2025
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
148 ft
2 main spans
Daily traffic
50,500
2009 count
Owner
State
State Highway Agency

About this bridge

Interstate 280 SB over Avalon Drive is a concrete continuous box beam or girders - multiple carrying Interstate 280 SB over Avalon Drive in San Mateo County, California. It was built in 1971, so it is 54 years old, younger than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 50,500 vehicles a day, roughly 2% of them trucks, projected to reach 72,237 by 2047. The structure is 148 ft (45.1 m) long and 70 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

CarriesInterstate 280 SB
CrossesAvalon Drive
Location04-SM-280-R22.04-SSF
RouteInterstate 280
Coordinates37.63942, -122.44184
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
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 geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating39.2 US tons
Inventory rating27.9 US tons

Structure

MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20 + Mod
Structure length148 ft (45.1 m)
Longest span83 ft (25.3 m)
Deck width70 ft (21.2 m)
Roadway width66 ft (20.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50,500 (2009)
Projected traffic72,237 by 2047
Trucks2%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$3.7 million (2018 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was Interstate 280 SB over Avalon Drive built?

It was built in 1971, making it 54 years old in 2025.

What condition is Interstate 280 SB over Avalon Drive in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in February 2025.

How much traffic does Interstate 280 SB over Avalon Drive carry?

About 50,500 vehicles per day (2009 count), of which roughly 2% are trucks.

How long is Interstate 280 SB over Avalon Drive?

The structure is 148 ft (45.1 m) long with a longest span of 83 ft (25.3 m) and a deck 70 ft wide.

Who owns Interstate 280 SB over Avalon Drive?

It is owned by the State Highway Agency.