Shiawassee County Bridge Report Card
Shiawassee County scores 59 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Shiawassee County, Michigan
Shiawassee County has 163 bridges in the National Bridge Inventory, with 15 rated poor and 21 rated scour-critical. Its poor-condition share of 9.2% is at or below the 11.0% statewide average. Poor-condition bridges carry about 52,246 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Shiawassee County a Bridge Condition Exposure Score of 59/100 (F). The county has 163 bridges in the National Bridge Inventory, including 15 in poor condition and 21 rated scour-critical. Poor-condition bridges carry about 52,246 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 | 9.2% | 18.4 |
| Poor-condition traffic exposure | 25 | 3.8% of measured traffic | 2.8 |
| Scour-critical bridge share | 20 | 12.9% | 20.0 |
| Average age vs national baseline | 10 | 44 years vs 48 nationally | 0.0 |
| Traffic-data completeness | 5 | 1,377,516 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 | 9.2% |
| State Poor-Condition Share | 11.0% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 12.9% |
| Average Bridge Age | 44 years |
| Poor-Condition Traffic Exposure | 52,246 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Shiawassee County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| Main ST over Holly Drain | Poor condition + traffic exposure | Poor | 1,209 | 1965 |
| Bennington Road over Bear Creek | Poor condition + traffic exposure | Poor | 1,026 | 1925 |
| Bath Road over S Br Lookingglass River | Poor condition + traffic exposure | Poor | 910 | 1925 |
| Vernon RD over Porter Creek | Poor condition + traffic exposure | Poor | 135 | 1938 |
| I-69 EB over Huron & Eastern Rr | Poor condition + traffic exposure | Poor | 14,378 | 1961 |
| I-69 EB over Cn Rr & Reed RD | Poor condition + traffic exposure | Poor | 13,840 | 1961 |
| I-69 WB over Cn Rr & Reed RD | Poor condition + traffic exposure | Poor | 13,840 | 1961 |
| New Lothrop Road over Shiawassee River | Poor condition + traffic exposure | Poor | 2,055 | 1955 |
| Durand Road over Northwood Creek | Poor condition + traffic exposure | Poor | 1,409 | 1930 |
| Bennington Road over Shiawassee River | Poor condition + traffic exposure | Poor | 1,096 | 1985 |
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.