Johnson County Bridge Report Card

Johnson County scores 79 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.

C79 / 100

Local infrastructure snapshot

Johnson County, Iowa

Johnson County has 376 bridges in the National Bridge Inventory, with 34 rated poor and 1 rated scour-critical. Its poor-condition share of 9.0% is at or below the 18.6% statewide average. Poor-condition bridges carry about 55,023 daily vehicle crossings.

376Total Bridges

34Poor (9.0%)

186Fair (49.5%)

1Scour-Critical

Quote-Ready Local Facts

9.0%of county bridges are in poor condition, compared with 18.6% statewide and 6.7% nationally.

55,023daily vehicle crossings are on poor-condition bridges in the county.

1bridges are rated scour-critical, or 0.3% of the county bridge inventory.

Copyable Facts for Reporters

BridgeLookup.com gives Johnson County a Bridge Condition Exposure Score of 79/100 (C). The county has 376 bridges in the National Bridge Inventory, including 34 in poor condition and 1 rated scour-critical. Poor-condition bridges carry about 55,023 daily vehicle crossings. Poor condition does not mean unsafe; bridges judged unsafe are closed or restricted by transportation agencies.

Download all county report-card scores as CSV.

How the Score Breaks Down

Factor	Weight	County Value	Penalty
Poor-condition bridge share	40	9.0%	18.1
Poor-condition traffic exposure	25	3.5% of measured traffic	2.6
Scour-critical bridge share	20	0.3%	0.5
Average age vs national baseline	10	46 years vs 48 nationally	0.0
Traffic-data completeness	5	1,565,584 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	9.0%
State Poor-Condition Share	18.6%
National Poor-Condition Share	6.7%
County Scour-Critical Share	0.3%
Average Bridge Age	46 years
Poor-Condition Traffic Exposure	55,023 vehicles/day

Bridges to Watch

Busiest Poor-Condition BridgeGilbert ST over Ralston Creek — 14,025 vehicles/day Oldest Listed BridgeCenter ST over Hurtzel Run — built in 1900 All County BridgesBrowse every bridge record in Johnson County.

Top Bridges to Watch in Johnson County

Bridge	Reason	Condition	Daily Traffic	Year Built
Iowa Johnson RD over Stream	Poor condition + traffic exposure	Poor	11	1925
Gilbert ST over Ralston Creek	Poor condition + traffic exposure	Poor	14,025	1972
Ia 1 NB over Iowa River	Poor condition + traffic exposure	Poor	10,950	1915
Iowa AVE over Iowa River	Poor condition + traffic exposure	Poor	5,400	1916
Kirkwood AVE over Ralston Creek	Poor condition + traffic exposure	Poor	4,693	1935
Dodge ST over Over Iais Rr	Poor condition + traffic exposure	Poor	4,688	1970
Washington ST over Ralston Creek	Poor condition + traffic exposure	Poor	2,487	1910
Johnson ST over Ralston Creek	Poor condition + traffic exposure	Poor	2,356	1930
Evans ST over Ralston Creek	Poor condition + traffic exposure	Poor	2,176	1911
FM 520th ST over Iowa River	Poor condition + traffic exposure	Poor	2,060	1971

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.