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:

STATE ROUTE 1 SB

Over: SOUTHGATE AVENUE

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

Built 1968 ADT: 13,300

STATE ROUTE 1 NB

Over: SOUTHGATE AVENUE

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

Built 1968 ADT: 13,300

INTERSTATE 280 SB

Over: STATE ROUTE 92

04-SM-280-10.81, San Mateo, CA

Built 1973 ADT: 22,200

INTERSTATE 280 NB

Over: STATE ROUTE 92

04-SM-280-10.81, San Mateo, CA

Built 1973 ADT: 72,000

N280-W92 CONNECTOR

Over: INTERSTATE 280, SR 92

04-SM-280-10.91, San Mateo, CA

Built 1974 ADT: 111,000

S280-E92 CONNECTOR

Over: INTERSTATE 280, SR 92

04-SM-280-10.80, San Mateo, CA

Built 1973 ADT: 111,000

INTERSTATE 280 SB

Over: EDGEWOOD ROAD

04-SM-280-6.65, San Mateo, CA

Built 1973 ADT: 3,500

INTERSTATE 280 NB

Over: EDGEWOOD ROAD

04-SM-280-6.65, San Mateo, CA

Built 1973 ADT: 3,500

PEDESTRIAN WALKWAY

Over: STATE ROUTE 84

04-SM-084-25.13-RDWC, San Mateo, CA

Built 1967 ADT: 43,000

SR 92 WB & RAMPS

Over: U.S. 101, MARINA LAGOON

04-SM-092-R11.78-SM, San Mateo, CA

Built 1971 ADT: 9,930

SR 92 EB & RAMPS

Over: U.S. 101, MARINA LAGOON

04-SM-092-R11.78-SM, San Mateo, CA

Built 1971 ADT: 4,610

INTERSTATE 380

Over: CALTRAIN,UP RR,BART,ETC

04-SM-380-5.73-SBR, San Mateo, CA

Built 1971 ADT: 13,100

E380-N101 CONNECTR

Over: I 380,US 101, RAMPS, 7TH

04-SM-380-6.37-SBR, San Mateo, CA

Built 1976 ADT: 11,000

INTERSTATE 380 WB

Over: US 101, RAMPS, CITY ST

04-SM-380-6.33-SBR, San Mateo, CA

Built 1976 ADT: 188,000

INTERSTATE 380 EB

Over: US 101, RAMPS, CITY ST

04-SM-380-6.32-SBR, San Mateo, CA

Built 1976 ADT: 188,000

S101-W380 CONNECTR

Over: 7TH AVENUE

04-SM-101-R20.65-SBR, San Mateo, CA

Built 1976 ADT: 4,500

INTERSTATE 380 WB

Over: 7TH AVENUE

04-SM-380-6.20-SBR, San Mateo, CA

Built 1976 ADT: 11,000

INTERSTATE 380 EB

Over: 7TH AVENUE

04-SM-380-6.20-SBR, San Mateo, CA

Built 1976 ADT: 11,000

N101-W380 CONNECTR

Over: I 380, US 101, 7TH, CONN

04-SM-101-R20.52, San Mateo, CA

Built 1976 ADT: 60,000

E380-S101 CONNECTR

Over: S101-SAN BRUNO AV,7TH AV

04-SM-380-6.19-SBR, San Mateo, CA

Built 1976 ADT: 11,950

SAN BRUNO AVENUE

Over: U.S. HIGHWAY 101

04-SM-101-R20.39-SBR, San Mateo, CA

Built 1976 ADT: 55,000

W380-N&S101 CONN

Over: US 101,I 380,EB CON,RMPS

04-SM-380-6.40-SBR, San Mateo, CA

Built 1976 ADT: 20,400

N&S101-E380 CNNCTR

Over: US 101, RMPS, NORTH CHNL

04-SM-101-R20.69-SBR, San Mateo, CA

Built 1976 ADT: 248,000

SFO AIRPRT-S101 ON

Over: U.S. HIGHWAY 101

04-SM-101-19.09, San Mateo, CA

Built 1987 ADT: 8,000

S101-SFO AIRPT OFF

Over: U.S. HIGHWAY 101

04-SM-101-19.26, San Mateo, CA

Built 1987 ADT: 16,900

INTERSTATE 280 SB

Over: CANADA ROAD

04-SM-280-R6.60, San Mateo, CA

Built 1973 ADT: 3,700

INTERSTATE 280 NB

Over: CANADA ROAD

04-SM-280-R6.60, San Mateo, CA

Built 1973 ADT: 3,700

MARINERS ISLAND BL

Over: STATE ROUTE 92

04-SM-092-R12.78-SM, San Mateo, CA

Built 1977 ADT: 105,000

CRYSTAL SP BIKE OC

Over: INTERSTATE 280

04-SM-280-10.56, San Mateo, CA

Built 1973 ADT: 109,000

SFO-W380 CONN RMP

Over: N101-SAN BRUNO OFF-RAMP

04-SM-380-6.44, San Mateo, CA

Built 1987 ADT: 6,000

N280-S1 CONNECTOR

Over: SOUTHGATE AVENUE

04-SM-280-R25.32-DLC, San Mateo, CA

Built 1968 ADT: 11,000

VINTAGE PARK DRIVE

Over: STATE ROUTE 92

04-SM-092-R13.25-FSTC, San Mateo, CA

Built 1991 ADT: 105,000

D ST-S280&S1 ONRMP

Over: I 280, SULLIVAN-S280 RMP

04-SM-280-R25.60-DLC, San Mateo, CA

Built 1993 ADT: 221,000

OYSTER POINT BLVD

Over: US HIGHWAY 101

04-SM-101-22.82-SSF, San Mateo, CA

Built 1994 ADT: 196,000

S101-OYSTER POINT

Over: US HIGHWAY 101

04-SM-101-22.78, San Mateo, CA

Built 2004 ADT: 6,000

OYSTER POINT-S101

Over: US HIGHWAY 101

04-SM-101-22.70-SSF, San Mateo, CA

Built 1995 ADT: 219,000

BART TRACKS

Over: STATE ROUTE 82

04-SM-082-23.00-CLM, San Mateo, CA

Built 1994 ADT: 28,500

S101-SFO AIRPT OFF

Over: US 101, 2 AIRPRT-S101 ON

04-SM-101-19.12, San Mateo, CA

Built 2000 ADT: 248,000

SFO AIRPRT-S101 ON

Over: U.S. HIGHWAY 101

04-SM-101-19.29, San Mateo, CA

Built 2000 ADT: 235,000

N101-SFO ARPRT OFF

Over: MILLBRAE AV-N101 ON RAMP

04-SM-101-18.54, San Mateo, CA

Built 2000 ADT: 8,000

UTILITIES/PIPES

Over: INTERSTATE 280

04-SM-280-R25.87-DLC, San Mateo, CA

Built 1998 ADT: 5,000

BART

Over: US101, I-380 AIRPRT RMPS

04-SM-101-19.30, San Mateo, CA

Built 2001 ADT: 248,000

PEDESTRIAN WALKWAY

Over: U.S. HIGHWAY 101

04-SM-101-9.72-BMT, San Mateo, CA

Built 2009 ADT: 236,000

ISLAND PARKWAY

Over: MARINE PKWY TO NB 101

04-SM-101-9.60-RDWC, San Mateo, CA

Built 2004 ADT: 5,000

PEDESTRIAN WALKWAY

Over: U.S. HIGHWAY 101

04-SM-101-16.53-BURL, San Mateo, CA

Built 2009 ADT: 15,000

PEDESTRIAN WALKWAY

Over: U.S. HIGHWAY 101

04-SM-101-13.95-SM, San Mateo, CA

Built 2009 ADT: 232,000

PEDESTRIAN WALKWAY

Over: U.S. HIGHWAY 101

04-SM-101-2.57-MLP, San Mateo, CA

Built 2012 ADT: 199,000

PENINSULA AVENUE

Over: U.S. HIGHWAY 101

04-SM-101-14.69-SM, San Mateo, CA

Built 2010 ADT: 232,000

BROADWAY AVE

Over: U.S. HIGHWAY 101

04-SM-101-16.61-BURL, San Mateo, CA

Built 2016 ADT: 226,000

PEDESTRIAN WALKWAY

Over: U.S. HIGHWAY 101,E FRONT

04-SM-101-0.47-EAPA, San Mateo, CA

Built 2019 ADT: 25,000

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

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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