US Bridges

Interstate 280 SB over Westborough Blvd

Good

San Mateo County, California · 04-SM-280-R22.62-SSF · Structure no. 35 0212L

Built
1967
58 years old
Condition
Good
inspected February 2025
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
179 ft
2 main spans
Daily traffic
89,000
2009 count
Owner
State
State Highway Agency

About this bridge

Interstate 280 SB over Westborough Blvd is a concrete continuous box beam or girders - multiple carrying Interstate 280 SB over Westborough Blvd in San Mateo County, California. It was built in 1967, so it is 58 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 89,000 vehicles a day, roughly 1% of them trucks, projected to reach 130,062 by 2045. The structure is 179 ft (54.6 m) long and 70 ft wide.

CarriesInterstate 280 SB
CrossesWestborough Blvd
Location04-SM-280-R22.62-SSF
RouteInterstate 280
Coordinates37.6451, -122.44927
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating88.6 US tons
Inventory rating53.2 US tons

Structure

MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length179 ft (54.6 m)
Longest span97 ft (29.5 m)
Deck width70 ft (21.2 m)
Roadway width66 ft (20.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic89,000 (2009)
Projected traffic130,062 by 2045
Trucks1%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
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 proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Interstate 280 SB over Westborough Blvd built?

It was built in 1967, making it 58 years old in 2025.

What condition is Interstate 280 SB over Westborough Blvd in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in February 2025.

How much traffic does Interstate 280 SB over Westborough Blvd carry?

About 89,000 vehicles per day (2009 count), of which roughly 1% are trucks.

How long is Interstate 280 SB over Westborough Blvd?

The structure is 179 ft (54.6 m) long with a longest span of 97 ft (29.5 m) and a deck 70 ft wide.

Who owns Interstate 280 SB over Westborough Blvd?

It is owned by the State Highway Agency.