Mellette County Bridge Report Card
Mellette County scores 66 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Mellette County, South Dakota
Mellette County has 28 bridges in the National Bridge Inventory, with 2 rated poor and 3 rated scour-critical. Its poor-condition share of 7.1% is at or below the 16.1% statewide average. Poor-condition bridges carry about 19 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Mellette County a Bridge Condition Exposure Score of 66/100 (D). The county has 28 bridges in the National Bridge Inventory, including 2 in poor condition and 3 rated scour-critical. Poor-condition bridges carry about 19 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 | 7.1% | 14.3 |
| Poor-condition traffic exposure | 25 | 0.2% of measured traffic | 0.1 |
| Scour-critical bridge share | 20 | 10.7% | 20.0 |
| Average age vs national baseline | 10 | 46 years vs 48 nationally | 0.0 |
| Traffic-data completeness | 5 | 9,606 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 | 7.1% |
| State Poor-Condition Share | 16.1% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 10.7% |
| Average Bridge Age | 46 years |
| Poor-Condition Traffic Exposure | 19 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Mellette County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Pine Creek (unorg) over Pine Ck | Poor condition + traffic exposure | Poor | 10 | 1992 |
| County Highway #7 over Cottonwood Ck | Poor condition + traffic exposure | Poor | 9 | 1982 |
| Sd044 over Black Pipe Ck | Scour-critical foundation rating | Fair | 302 | 1987 |
| County Highway #23 over White Horse Ck | Scour-critical foundation rating | Fair | 55 | 1957 |
| County Highway #11 over Little White Rv | Scour-critical foundation rating | Fair | 35 | 1962 |
| IRR Ar Us083 over Ck | High traffic | Good | 1,525 | 1965 |
| IRR Ar Us083 over Horse Head Ck | High traffic | Fair | 1,525 | 1966 |
| Us083 over White Rv | High traffic | Good | 1,188 | 2021 |
| Us083 over Little White Rv | High traffic | Good | 1,188 | 2022 |
| Sd044 over Little White Rv | High traffic | Fair | 739 | 1973 |
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.