Boise County Bridge Report Card
Boise County scores 75 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Boise County, Idaho
Boise County has 89 bridges in the National Bridge Inventory, with 5 rated poor and 6 rated scour-critical. Its poor-condition share of 5.6% is above the 5.4% statewide average. Poor-condition bridges carry about 220 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Boise County a Bridge Condition Exposure Score of 75/100 (C). The county has 89 bridges in the National Bridge Inventory, including 5 in poor condition and 6 rated scour-critical. Poor-condition bridges carry about 220 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 | 5.6% | 11.2 |
| Poor-condition traffic exposure | 25 | 0.2% of measured traffic | 0.2 |
| Scour-critical bridge share | 20 | 6.7% | 13.5 |
| Average age vs national baseline | 10 | 47 years vs 48 nationally | 0.0 |
| Traffic-data completeness | 5 | 104,028 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 | 5.6% |
| State Poor-Condition Share | 5.4% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 6.7% |
| Average Bridge Age | 47 years |
| Poor-Condition Traffic Exposure | 220 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Boise County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Anderson Creek RD over Anderson Creek | Poor condition + traffic exposure | Poor | 100 | 1983 |
| Boulder Creek Road over Mores Creek | Poor condition + traffic exposure | Poor | 50 | 1982 |
| Cottonwd-bannock over Mores Creek | Poor condition + traffic exposure | Poor | 30 | 1962 |
| Shafer Creek Road over Shafer Creek | Poor condition + traffic exposure | Poor | 20 | 1914 |
| Avelene Ck. Road over Grimes Creek | Poor condition + traffic exposure | Poor | 20 | 1954 |
| SH 55 over S.fk.payette River | Scour-critical foundation rating | Fair | 7,300 | 1955 |
| SH 55 over N.fk.payette River | Scour-critical foundation rating | Fair | 4,700 | 1984 |
| SH 21 over Clear Creek;at Lowman | Scour-critical foundation rating | Fair | 1,200 | 1939 |
| SH 21 over S.fk.payette R;lowman Br | Scour-critical foundation rating | Fair | 410 | 1948 |
| Banks Grade over N. Fk. Payette River | Scour-critical foundation rating | Good | 350 | 1957 |
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.