Ontonagon County Bridge Report Card
Ontonagon County scores 37 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Ontonagon County, Michigan
Ontonagon County has 66 bridges in the National Bridge Inventory, with 10 rated poor and 7 rated scour-critical. Its poor-condition share of 15.2% is above the 11.0% statewide average. Poor-condition bridges carry about 7,888 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Ontonagon County a Bridge Condition Exposure Score of 37/100 (F). The county has 66 bridges in the National Bridge Inventory, including 10 in poor condition and 7 rated scour-critical. Poor-condition bridges carry about 7,888 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 | 15.2% | 30.3 |
| Poor-condition traffic exposure | 25 | 13.5% of measured traffic | 10.1 |
| Scour-critical bridge share | 20 | 10.6% | 20.0 |
| Average age vs national baseline | 10 | 54 years vs 48 nationally | 2.5 |
| Traffic-data completeness | 5 | 58,572 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 | 15.2% |
| State Poor-Condition Share | 11.0% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 10.6% |
| Average Bridge Age | 54 years |
| Poor-Condition Traffic Exposure | 7,888 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Ontonagon County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| M-28 over Wapato Creek | Poor condition + traffic exposure | Poor | 1,845 | 1938 |
| Gardner Road over E Branch Ontonogon River | Poor condition + traffic exposure | Poor | 100 | 1954 |
| Us-45 over Clear Creek | Poor condition + traffic exposure | Poor | 1,648 | 1931 |
| M-64 over Pine River | Poor condition + traffic exposure | Poor | 1,032 | 1968 |
| Old M-107 over Big Iron River | Poor condition + traffic exposure | Poor | 831 | 1938 |
| Old M-107 over Little Iron River | Poor condition + traffic exposure | Poor | 831 | 1967 |
| Old M-107 over Union River | Poor condition + traffic exposure | Poor | 831 | 1976 |
| Bond Falls Road over Mid Br Ontonagon River | Poor condition + traffic exposure | Poor | 400 | 1940 |
| Main ST over Mineral River | Poor condition + traffic exposure | Poor | 250 | 1955 |
| Lakeshore Drive over Firesteel River | Poor condition + traffic exposure | Poor | 120 | 1976 |
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.