US Bridges

Junipero SERRA-NB1 over Interstate 280

Fair

San Mateo County, California · 04-SM-001-R48.38-DLC · Structure no. 35 0175S

Built
1965
60 years old
Condition
Fair
inspected October 2024
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
610 ft
7 main spans
Daily traffic
6,600
1998 count
Owner
State
State Highway Agency

About this bridge

Junipero SERRA-NB1 over Interstate 280 is a concrete continuous box beam or girders - multiple carrying Junipero SERRA-NB1 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 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 6,600 vehicles a day, roughly 2% of them trucks, projected to reach 21,517 by 2046. The structure is 610 ft (185.9 m) long and 34 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

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CarriesJunipero SERRA-NB1
CrossesInterstate 280
Location04-SM-001-R48.38-DLC
RouteState Highway 1
CountySan Mateo County
StateCalifornia
Coordinates37.70556, -122.47075
Functional classUrban Principal Arterial - Other Freeway or Expressway

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment6: Equal to present minimum criteria
Operating rating110 US tons
Inventory rating93.9 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans7
Design loadHS 20 + Mod
Structure length610 ft (185.9 m)
Longest span111 ft (33.7 m)
Deck width34 ft (10.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,600 (1998)
Projected traffic21,517 by 2046
Trucks2%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.1 mi (5 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 Junipero SERRA-NB1 over Interstate 280 built?

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

What condition is Junipero SERRA-NB1 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 October 2024.

How much traffic does Junipero SERRA-NB1 over Interstate 280 carry?

About 6,600 vehicles per day (1998 count), of which roughly 2% are trucks.

How long is Junipero SERRA-NB1 over Interstate 280?

The structure is 610 ft (185.9 m) long with a longest span of 111 ft (33.7 m) and a deck 34 ft wide.

Who owns Junipero SERRA-NB1 over Interstate 280?

It is owned by the State Highway Agency.