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:

SAND HILL ROAD (S)

Over: INTERSTATE 280

04-SM-280-R1.56, San Mateo, CA

Built 1969 ADT: 101,000

SAND HILL ROAD (N)

Over: INTERSTATE 280

04-SM-280-R1.61, San Mateo, CA

Built 1969 ADT: 101,000

I-280 SOUTHBOUND

Over: ALPINE RD & LOS TRANCOS

04-SM-280-R0.01, San Mateo, CA

Built 1969 ADT: 3,500

I-280 NORTHBOUND

Over: ALPINE RD & LOS TRANCOS

04-SM-280-R0.01, San Mateo, CA

Built 1969 ADT: 3,500

CALTRAIN & UP RR

Over: U.S. HIGHWAY 101

04-SM-101-3.05-MLP, San Mateo, CA

Built 1931 ADT: 199,000

MANOR DRIVE

Over: STATE ROUTE 1

04-SM-001-R45.12-PFA, San Mateo, CA

Built 1965 ADT: 32,500

THIRD AVENUE

Over: US HIGHWAY 101

04-SM-101-13.46-SM, San Mateo, CA

Built 1953 ADT: 20,000

FASHION ISLAND BL

Over: US HIGHWAY 101

04-SM-101-11.90-SM, San Mateo, CA

Built 1985 ADT: 236,000

HOLLY STREET

Over: US HIGHWAY 101

04-SM-101-8.40, San Mateo, CA

Built 1954 ADT: 20,000

BUNKER HILL DRIVE

Over: INTERSTATE 280

04-SM-280-R12.32, San Mateo, CA

Built 1969 ADT: 111,000

W380-N280 CONNECTR

Over: N280 ON-RAMP COLLECTOR

04-SM-380-T4.71, San Mateo, CA

Built 1971 ADT: 15,000

S101-S84 CONNECTOR

Over: UP RR SPUR & VETERANS BL

04-SM-101-5.50-RDWC, San Mateo, CA

Built 1972 ADT: 22,600

SR 84 (MARSH RD)

Over: US HIGHWAY 101

04-SM-084-R25.81-MLP, San Mateo, CA

Built 1998 ADT: 199,000

N101-S84 CONNECTOR

Over: WOODSIDE ROAD

04-SM-101-5.39-RDWC, San Mateo, CA

Built 1958 ADT: 1,210

U.S. HIGHWAY 101

Over: SR 84 (WOODSIDE ROAD)

04-SM-101-5.39-RDWC, San Mateo, CA

Built 1958 ADT: 43,000

MAPLE STREET

Over: US HIGHWAY 101

04-SM-101-5.88-RDWC, San Mateo, CA

Built 1958 ADT: 195,000

MILLBRAE AVENUE

Over: U.S. HIGHWAY 101

04-SM-101-17.95-MLBR, San Mateo, CA

Built 1947 ADT: 226,000

STATE ROUTE 84

Over: SR 82 - EL CAMINO REAL

04-SM-084-24.68-RDWC, San Mateo, CA

Built 1965 ADT: 35,250

US HIGHWAY 101 SB

Over: CALTRAIN,UP RR,GRAND,ONR

04-SM-101-21.92-SSF, San Mateo, CA

Built 1948 ADT: 18,600

US HIGHWAY 101 NB

Over: CALTRAIN,UP RR,GRAND,ONR

04-SM-101-21.92-SSF, San Mateo, CA

Built 1948 ADT: 95,100

UNIVERSITY AVE NB

Over: US HIGHWAY 101

04-SM-101-0.88-EAPA, San Mateo, CA

Built 1958 ADT: 199,000

RALSTON AVENUE

Over: US HIGHWAY 101

04-SM-101-9.55-BMT, San Mateo, CA

Built 1974 ADT: 195,000

INTERSTATE 280 SB

Over: HICKEY BOULEVARD

04-SM-280-R24.20-DLC, San Mateo, CA

Built 1967 ADT: 22,200

INTERSTATE 280 NB

Over: HICKEY BOULEVARD

04-SM-280-R24.20-DLC, San Mateo, CA

Built 1967 ADT: 22,200

U.S. HIGHWAY 101

Over: AIRPORT BOULEVARD

04-SM-101-21.69-SSF, San Mateo, CA

Built 1947 ADT: 9,280

WHIPPLE AVENUE

Over: US HIGHWAY 101

04-SM-101-6.62-RDWC, San Mateo, CA

Built 1958 ADT: 195,000

N101-BAYSHORE OFF

Over: US HIGHWAY 101

04-SM-101-23.39-SSF, San Mateo, CA

Built 1957 ADT: 219,000

EAST HILLSDALE BL

Over: US HIGHWAY 101

04-SM-101-11.15-SM, San Mateo, CA

Built 1954 ADT: 15,000

UNIVERSITY AVE SB

Over: US HIGHWAY 101

04-SM-101-0.89-EAPA, San Mateo, CA

Built 1958 ADT: 199,000

WB STATE ROUTE 92

Over: STATE ROUTE 82

04-SM-092-R11.19-SM, San Mateo, CA

Built 1963 ADT: 32,000

EB STATE ROUTE 92

Over: STATE ROUTE 82

04-SM-092-R11.19-SM, San Mateo, CA

Built 1963 ADT: 32,000

WB STATE ROUTE 92

Over: CALTRAIN,UP RR,PACIFIC,

04-SM-092-R11.38-SM, San Mateo, CA

Built 1963 ADT: 300

EB STATE ROUTE 92

Over: CALTRAIN,UP RR,PACIFIC,

04-SM-092-R11.38-SM, San Mateo, CA

Built 1963 ADT: 300

WB STATE ROUTE 92

Over: DELAWARE STREET

04-SM-092-R11.61-SM, San Mateo, CA

Built 1963 ADT: 400

EB STATE ROUTE 92

Over: DELAWARE STREET

04-SM-092-R11.61-SM, San Mateo, CA

Built 1963 ADT: 300

STATE ROUTE 92

Over: PALM AVENUE

04-SM-092-R11.30-SM, San Mateo, CA

Built 1963 ADT: 6,460

ALAMEDA DE LAS PUL

Over: STATE ROUTE 92

04-SM-092-R10.56-SM, San Mateo, CA

Built 1963 ADT: 72,000

STATE ROUTE 92

Over: WEST HILLSDALE BLVD

04-SM-092-R9.38-SM, San Mateo, CA

Built 1967 ADT: 33,000

SHARP PARK ROAD

Over: STATE ROUTE 1

04-SM-001-R43.46-PFA, San Mateo, CA

Built 1965 ADT: 32,500

JOHN DALY BLVD

Over: INTERSTATE 280, SR 1

04-SM-280-M27.17L-DLC, San Mateo, CA

Built 1965 ADT: 141,000

S280-JUNIPERO SERR

Over: INTERSTATE 280

04-SM-280-M27.20L-DLC, San Mateo, CA

Built 1965 ADT: 141,000

JUNIPERO SERRA-NB1

Over: INTERSTATE 280

04-SM-001-R48.38-DLC, San Mateo, CA

Built 1965 ADT: 141,000

ST CHARLES AVENUE

Over: INTERSTATE 280

04-SM-280-M27.41L-DLC, San Mateo, CA

Built 1965 ADT: 141,000

INTERSTATE 280

Over: SOUTHGATE AVENUE

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

Built 1967 ADT: 11,000

N280-S1 CONNECTOR

Over: I 280, SR 1, & CONNS

04-SM-280-R25.26-DLC, San Mateo, CA

Built 1967 ADT: 74,000

STATE ROUTE 1 NB

Over: INTERSTATE 280

04-SM-001-R47.76-DLC, San Mateo, CA

Built 1967 ADT: 207,000

SAN PEDRO ROAD

Over: INTERSTATE 280

04-SM-280-R25.78-DLC, San Mateo, CA

Built 1965 ADT: 221,000

JUNIPERO SERRA BL

Over: INTERSTATE 280

04-SM-280-R26.04-DLC, San Mateo, CA

Built 1965 ADT: 207,000

SCHOOL STREET

Over: INTERSTATE 280

04-SM-280-R26.35-DLC, San Mateo, CA

Built 1965 ADT: 207,000

JUNIPERO SERRA BLV

Over: INTERSTATE 280

04-SM-280-R26.50-DLC, San Mateo, CA

Built 1965 ADT: 207,000

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