San Mateo County, CA

393 public highway bridges

San Mateo County Bridge Snapshot

San Mateo County, California contains 393 public highway bridges in the FHWA National Bridge Inventory. Roughly 16.3% are rated “Good,” 31.3% “Fair,” 5.3% “Poor,” and 5.3% are classified as structurally deficient — the federal designation for spans whose deck, superstructure, or substructure has been rated 4 or below on the 0–9 NBI scale. Structurally deficient does not mean unsafe to cross; it means the bridge is on the priority list for repair or replacement.

Inspections in CA are conducted by certified engineers from the state Department of Transportation on a 24-month cycle, and results are reported back to the FHWA each spring. The list below shows every NBI-tracked bridge in the county, sorted by inventory load rating. Use the “Sort by” controls to surface the lowest-rated spans first, and click any row for full inspection history, traffic counts, and condition trends.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

393

Total Bridges

16.3%

Good

5.3%

Poor

5.3%

Structurally Deficient

Condition Distribution

Good

16.3% (64)

Fair

31.3% (123)

Poor

5.3% (21)

SD

5.3% (21)

All Bridges (393)

Sort:

WASHINGTON STREET

Over: INTERSTATE 280

04-SM-280-R25.97-DLC, San Mateo, CA

Built 1965 ADT: 207,000

SULLIVAN-S280 ONRP

Over: S280-S1 CONNECTOR RAMP

04-SM-280-R25.34-DLC, San Mateo, CA

Built 1967 ADT: 221,000

PALOMA AVENUE

Over: STATE ROUTE 1

04-SM-001-R44.21-PFA, San Mateo, CA

Built 1965 ADT: 32,500

PEDESTRIAN WALKWAY

Over: STATE ROUTE 1

04-SM-001-R44.88-PFA, San Mateo, CA

Built 1965 ADT: 32,500

FOSTER CITY BLVD

Over: STATE ROUTE 92

04-SM-092-R13.61-FSTC, San Mateo, CA

Built 1967 ADT: 86,000

STATE ROUTE 1

Over: GATEWAY DRIVE

04-SM-001-R46.51-DLC, San Mateo, CA

Built 1964 ADT: 7,990

INTERSTATE 280 SB

Over: CRYSTAL SPRINGS OFF-RAMP

04-SM-280-R20.04-SBR, San Mateo, CA

Built 1967 ADT: 44,650

S280-CRYSTAL SP OR

Over: WHITMAN WAY

04-SM-280-R20.22-SBR, San Mateo, CA

Built 1967 ADT: 15,000

INTERSTATE 280 SB

Over: WHITMAN WAY

04-SM-280-R20.22-SBR, San Mateo, CA

Built 1967 ADT: 15,000

INTERSTATE 280 NB

Over: WHITMAN WAY

04-SM-280-R20.22-SBR, San Mateo, CA

Built 1967 ADT: 15,000

HILLSDALE BLVD

Over: STATE ROUTE 82

04-SM-082-9.35-SM, San Mateo, CA

Built 1965 ADT: 37,000

N280-N35 CNNTR RMP

Over: INTERSTATE 280

04-SM-035-L23.00-SBR, San Mateo, CA

Built 1967 ADT: 110,000

CRYSTAL SPRINGS RD

Over: INTERSTATE 280

04-SM-280-R19.36-SBR, San Mateo, CA

Built 1967 ADT: 111,000

INTERSTATE 280 SB

Over: KING DRIVE

04-SM-280-R23.16-DLC, San Mateo, CA

Built 1967 ADT: 6,610

INTERSTATE 280 NB

Over: KING DRIVE

04-SM-280-R23.16-DLC, San Mateo, CA

Built 1967 ADT: 6,610

STATE ROUTE 92

Over: DE ANZA BOULEVARD

04-SM-092-R8.67-SM, San Mateo, CA

Built 1967 ADT: 9,510

S1-S35 CONNECTOR

Over: STATE ROUTE 1

04-SM-001-R46.65-DLC, San Mateo, CA

Built 1972 ADT: 43,500

SB STATE ROUTE 35

Over: NB & SB RTE 1 AND RAMPS

04-SM-035-R28.66-DLC, San Mateo, CA

Built 1972 ADT: 25,000

NB STATE ROUTE 35

Over: NB & SB RTE 1 AND RAMPS

04-SM-035-R28.66-DLC, San Mateo, CA

Built 1972 ADT: 43,500

RALSTON POLHEMUS R

Over: STATE ROUTE 92

04-SM-092-R7.93, San Mateo, CA

Built 1967 ADT: 8,200

SB STATE RTE 280

Over: SERRAMONTE BOULEVARD

04-SM-280-R24.63-DLC, San Mateo, CA

Built 1967 ADT: 15,400

NB STATE RTE 280

Over: SERRAMONTE BOULEVARD

04-SM-280-R24.63-DLC, San Mateo, CA

Built 1967 ADT: 15,400

STATE ROUTE 280 SB

Over: HAYNE ROAD

04-SM-280-R14.22-HIL, San Mateo, CA

Built 1969 ADT: 2,020

STATE ROUTE 280 NB

Over: HAYNE ROAD

04-SM-280-R14.22-HIL, San Mateo, CA

Built 1969 ADT: 2,020

STATE ROUTE 280 SB

Over: HILLCREST BOULEVARD

04-SM-280-R17.92-MLBR, San Mateo, CA

Built 1969 ADT: 3,500

STATE ROUTE 280 NB

Over: HILLCREST BOULEVARD

04-SM-280-R17.92-MLBR, San Mateo, CA

Built 1969 ADT: 3,500

INTERSTATE 280 SB

Over: WESTBOROUGH BLVD

04-SM-280-R22.62-SSF, San Mateo, CA

Built 1967 ADT: 8,500

INTERSTATE 280 NB

Over: WESTBOROUGH BLVD

04-SM-280-R22.62-SSF, San Mateo, CA

Built 1967 ADT: 8,500

SB STATE RTE 280

Over: LARKSPUR DRIVE

04-SM-280-R18.52-MLBR, San Mateo, CA

Built 1969 ADT: 8,500

NB STATE RTE 280

Over: LARKSPUR DRIVE

04-SM-280-R18.52-MLBR, San Mateo, CA

Built 1969 ADT: 8,500

INTERSTATE 280

Over: I 380 & S280-E380 CNNCTR

04-SM-280-R20.97-SBR, San Mateo, CA

Built 1971 ADT: 89,300

SAN BRUNO-N280 ONR

Over: S280-E380 CONNECTOR RAMP

04-SM-280-R20.96-SBR, San Mateo, CA

Built 1971 ADT: 150,000

W380-S280 CONNECTR

Over: I 280, CONN, FRNTGE RD

04-SM-380-4.65-SBR, San Mateo, CA

Built 1971 ADT: 156,000

WB RTE380 (FUTURE)

Over: S280-E380 CONNECTOR RAMP

04-SM-380-4.67-SBR, San Mateo, CA

Built 1973 ADT: 43,500

EB RTE380 (FUTURE)

Over: S280-E380 CONNECTOR RAMP

04-SM-380-4.67-SBR, San Mateo, CA

Built 1973 ADT: 43,500

INTERSTATE 380

Over: SR 82 (EL CAMINO REAL)

04-SM-380-5.45-SBR, San Mateo, CA

Built 1971 ADT: 36,000

SNEATH LANE

Over: INTERSTATE 280

04-SM-280-R21.30-SBR, San Mateo, CA

Built 1971 ADT: 101,000

INTERSTATE 380

Over: CHERRY AVENUE

04-SM-380-T4.98-SBR, San Mateo, CA

Built 1971 ADT: 4,950

INTERSTATE 280

Over: SAN BRUNO AVENUE

04-SM-280-R20.75-SBR, San Mateo, CA

Built 1971 ADT: 8,000

INTERSTATE 280 SB

Over: AVALON DRIVE

04-SM-280-R22.04-SSF, San Mateo, CA

Built 1971 ADT: 19,000

INTERSTATE 280 NB

Over: AVALON DRIVE

04-SM-280-R22.04-SSF, San Mateo, CA

Built 1971 ADT: 19,000

INTERSTATE 280

Over: FARM HILL BOULEVARD

04-SM-280-R4.65-WDS, San Mateo, CA

Built 1969 ADT: 3,700

INTERSTATE 280 NB

Over: FARM HILL BOULEVARD

04-SM-280-R4.65-WDS, San Mateo, CA

Built 1969 ADT: 3,700

INTERSTATE 280 SB

Over: CANADA ROAD

04-SM-280-R4.99-WDS, San Mateo, CA

Built 1969 ADT: 3,700

INTERSTATE 280 NB

Over: CANADA ROAD

04-SM-280-R4.99-WDS, San Mateo, CA

Built 1969 ADT: 3,700

INTERSTATE 280 SB

Over: SR 84 (WOODSIDE EXP)

04-SM-280-R3.32-WDS, San Mateo, CA

Built 1969 ADT: 29,750

INTERSTATE 280 NB

Over: SR 84 (WOODSIDE EXP)

04-SM-280-R3.32-WDS, San Mateo, CA

Built 1969 ADT: 30,000

STATE ROUTE 1

Over: ST. FRANCIS BOULEVARD

04-SM-001-R47.03-DLC, San Mateo, CA

Built 1972 ADT: 4,630

STATE ROUTE 1

Over: CLARINADA AVENUE

04-SM-001-R47.27-DLC, San Mateo, CA

Built 1968 ADT: 8,220

N1-S280 CONNECTOR

Over: SOUTHGATE AVENUE

04-SM-001-R47.62-DLC, San Mateo, CA

Built 1968 ADT: 13,300

Read our methodology — how this data is sourced, computed, and verified.

Related

Browse all → | Rankings →

Data sourced from official U.S. government datasets. See our methodology for details. Retrieved and formatted by PlainBridges Editorial

Reviewed byPlainbridges Editorial, Plain Bridges Editorial Team · June 6, 2026