San Mateo County Bridge Report Card
San Mateo County scores 64 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
San Mateo County, California
San Mateo County has 361 bridges in the National Bridge Inventory, with 37 rated poor and 5 rated scour-critical. Its poor-condition share of 10.2% is above the 4.9% statewide average. Poor-condition bridges carry about 1,454,025 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives San Mateo County a Bridge Condition Exposure Score of 64/100 (D). The county has 361 bridges in the National Bridge Inventory, including 37 in poor condition and 5 rated scour-critical. Poor-condition bridges carry about 1,454,025 daily vehicle crossings. Poor condition does not mean unsafe; bridges judged unsafe are closed or restricted by transportation agencies.
How the Score Breaks Down
| Factor | Weight | County Value | Penalty |
|---|---|---|---|
| Poor-condition bridge share | 40 | 10.2% | 20.5 |
| Poor-condition traffic exposure | 25 | 11.8% of measured traffic | 8.8 |
| Scour-critical bridge share | 20 | 1.4% | 2.8 |
| Average age vs national baseline | 10 | 59 years vs 48 nationally | 4.3 |
| Traffic-data completeness | 5 | 12,344,642 measured daily crossings | 0.0 |
Score = 100 minus weighted penalties. The score is a comparative research signal, not an official safety rating. Read the full methodology.
County Comparisons
| County Poor-Condition Share | 10.2% |
| State Poor-Condition Share | 4.9% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 1.4% |
| Average Bridge Age | 59 years |
| Poor-Condition Traffic Exposure | 1,454,025 vehicles/day |
Bridges to Watch
Top Bridges to Watch in San Mateo County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Wurr RD over Pescadero Creek | Poor condition + traffic exposure | Poor | 91 | 1962 |
| U.s. Highway 101 over Cordilleras Creek | Poor condition + traffic exposure | Poor | 195,000 | 1930 |
| Interstate 280 over Southgate Avenue | Poor condition + traffic exposure | Poor | 178,000 | 1967 |
| State Route 92 over San Francisco Bay | Poor condition + traffic exposure | Poor | 120,000 | 1967 |
| US Highway 101 SB over Caltrain Up Rr Grand Onr | Poor condition + traffic exposure | Poor | 98,000 | 1948 |
| US Highway 101 NB over Caltrain Up Rr Grand Onr | Poor condition + traffic exposure | Poor | 98,000 | 1948 |
| SB State RTE 280 over Serramonte Boulevard | Poor condition + traffic exposure | Poor | 89,000 | 1967 |
| NB State RTE 280 over Serramonte Boulevard | Poor condition + traffic exposure | Poor | 89,000 | 1967 |
| Interstate 280 SB over Avalon Drive | Poor condition + traffic exposure | Poor | 50,500 | 1971 |
| Interstate 280 NB over Avalon Drive | Poor condition + traffic exposure | Poor | 50,500 | 1971 |
Important safety note
Poor condition does not mean a bridge is unsafe. It means at least one major component has significant deterioration and the bridge is a priority for maintenance, repair, or replacement. Bridges judged unsafe are closed or restricted by transportation agencies.