Ziebach County Bridge Report Card
Ziebach County scores 52 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Ziebach County, South Dakota
Ziebach County has 30 bridges in the National Bridge Inventory, with 3 rated poor and 4 rated scour-critical. Its poor-condition share of 10.0% is at or below the 16.1% statewide average. Poor-condition bridges carry about 616 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Ziebach County a Bridge Condition Exposure Score of 52/100 (F). The county has 30 bridges in the National Bridge Inventory, including 3 in poor condition and 4 rated scour-critical. Poor-condition bridges carry about 616 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 | 10.0% | 20.0 |
| Poor-condition traffic exposure | 25 | 5.6% of measured traffic | 4.2 |
| Scour-critical bridge share | 20 | 13.3% | 20.0 |
| Average age vs national baseline | 10 | 56 years vs 48 nationally | 3.3 |
| Traffic-data completeness | 5 | 10,923 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 | 10.0% |
| State Poor-Condition Share | 16.1% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 13.3% |
| Average Bridge Age | 56 years |
| Poor-Condition Traffic Exposure | 616 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Ziebach County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| IRR Sd063 over Dupree Ck | Poor condition + traffic exposure | Poor | 590 | 1961 |
| Four Corners Road over Ck | Poor condition + traffic exposure | Poor | 16 | 1930 |
| IRR County Road over Bear Ck | Poor condition + traffic exposure | Poor | 10 | 1935 |
| IRR Us212 over Bear Ck | Scour-critical foundation rating | Fair | 1,130 | 1954 |
| Thunder Butte Road over Thunder Butte Ck | Scour-critical foundation rating | Fair | 143 | 1969 |
| Thunder Butte Road over Moreau Rv | Scour-critical foundation rating | Fair | 143 | 1969 |
| IRR Us212 over Ck | High traffic | Fair | 1,291 | 1954 |
| IRR Us212 over Bear Ck | High traffic | Fair | 1,083 | 1955 |
| IRR BIA RTE 6 over Ash Creek | High traffic | Good | 814 | 1968 |
| IRR Sd063 over Rudey Ck | High traffic | Fair | 590 | 1993 |
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.