Winnebago County Bridge Report Card
Winnebago County scores 81 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.
Winnebago County, Illinois
Winnebago County has 465 bridges in the National Bridge Inventory, with 32 rated poor and 3 rated scour-critical. Its poor-condition share of 6.9% is at or below the 9.5% statewide average. Poor-condition bridges carry about 170,200 daily vehicle crossings.
Quote-Ready Local Facts
Copyable Facts for Reporters
BridgeLookup.com gives Winnebago County a Bridge Condition Exposure Score of 81/100 (B). The county has 465 bridges in the National Bridge Inventory, including 32 in poor condition and 3 rated scour-critical. Poor-condition bridges carry about 170,200 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 | 6.9% | 13.8 |
| Poor-condition traffic exposure | 25 | 4.7% of measured traffic | 3.5 |
| Scour-critical bridge share | 20 | 0.6% | 1.3 |
| Average age vs national baseline | 10 | 48 years vs 48 nationally | 0.0 |
| Traffic-data completeness | 5 | 3,639,945 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 | 6.9% |
| State Poor-Condition Share | 9.5% |
| National Poor-Condition Share | 6.7% |
| County Scour-Critical Share | 0.6% |
| Average Bridge Age | 48 years |
| Poor-Condition Traffic Exposure | 170,200 vehicles/day |
Bridges to Watch
Top Bridges to Watch in Winnebago County
| Bridge | Reason | Condition | Daily Traffic | Year Built |
|---|---|---|---|---|
| 15th AVE over Rock River | Poor condition + traffic exposure | Poor | 5,750 | 1980 |
| Prairie Hill RD over Rock River | Poor condition + traffic exposure | Poor | 4,200 | 1966 |
| I-39 SB over Harrison AVE | Poor condition + traffic exposure | Poor | 25,450 | 1963 |
| I-39 NB over Harrison AVE | Poor condition + traffic exposure | Poor | 21,150 | 1963 |
| Ill 251 S B over Up Rr | Poor condition + traffic exposure | Poor | 13,000 | 1967 |
| Ill 251 N B over Up Rr | Poor condition + traffic exposure | Poor | 13,000 | 1967 |
| Auburn St. over Kent Creek | Poor condition + traffic exposure | Poor | 12,400 | 1930 |
| Roscoe RD over Rock River | Poor condition + traffic exposure | Poor | 10,700 | 1967 |
| 11th Street over Keith Creek | Poor condition + traffic exposure | Poor | 9,300 | 1915 |
| Springfield AVE over N Fork Kent Creek | Poor condition + traffic exposure | Poor | 8,500 | 1959 |
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.