Sierra County Bridge Report Card
Sierra County scores 81 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Sierra County, California
Sierra County has 66 bridges in the National Bridge Inventory, with 4 rated poor and 0 rated scour-critical. Its poor-condition share of 6.1% is above the 4.9% statewide average. Poor-condition bridges carry about 2,540 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Sierra County a Bridge Condition Exposure Score of 81/100 (B). The county has 66 bridges in the National Bridge Inventory, including 4 in poor condition and 0 rated scour-critical. Poor-condition bridges carry about 2,540 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 | 6.1% | 12.1 |
| Poor-condition traffic exposure | 25 | 7.1% of measured traffic | 5.3 |
| Scour-critical bridge share | 20 | 0.0% | 0.0 |
| Average age vs national baseline | 10 | 52 years vs 48 nationally | 1.7 |
| Traffic-data completeness | 5 | 35,640 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 | 6.1% |
| State Poor-Condition Share | 4.9% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 0.0% |
| Average Bridge Age | 52 years |
| Poor-Condition Traffic Exposure | 2,540 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Sierra County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Railroad Avenue over East Branch Smithneck CR | Poor condition + traffic exposure | Poor | 1,000 | 1987 |
| Westside RD over South Branch Carman Crk | Poor condition + traffic exposure | Poor | 670 | 1950 |
| Westside RD over North Branch Carman Crk | Poor condition + traffic exposure | Poor | 670 | 1950 |
| Packer Lake Road over Salmon Creek | Poor condition + traffic exposure | Poor | 200 | 1960 |
| U.s. Highway 395 over Long Valley RD | High traffic | Good | 4,600 | 1976 |
| U.s. Highway 395 over Long Valley RD | High traffic | Good | 2,300 | 1976 |
| State Route 89 over Little Truckee River | High traffic | Fair | 2,000 | 1982 |
| State Route 49 over Smithneck Creek | High traffic | Good | 1,900 | 1965 |
| State Route 89 over Turner Canyon | High traffic | Good | 1,400 | 1975 |
| State Route 49 over Downie River | High traffic | Good | 1,200 | 1938 |
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.