Day County Bridge Report Card

Day County scores 45 out of 100 on BridgeLookup's Bridge Condition Exposure Score, based on FHWA National Bridge Inventory records.

F45 / 100

Local infrastructure snapshot

Day County, South Dakota

Day County has 34 bridges in the National Bridge Inventory, with 9 rated poor and 0 rated scour-critical. Its poor-condition share of 26.5% is above the 16.1% statewide average. Poor-condition bridges carry about 796 daily vehicle crossings.

34Total Bridges

9Poor (26.5%)

10Fair (29.4%)

0Scour-Critical

Quote-Ready Local Facts

26.5%of county bridges are in poor condition, compared with 16.1% statewide and 6.7% nationally.

796daily vehicle crossings are on poor-condition bridges in the county.

0bridges are rated scour-critical, or 0.0% of the county bridge inventory.

Copyable Facts for Reporters

BridgeLookup.com gives Day County a Bridge Condition Exposure Score of 45/100 (F). The county has 34 bridges in the National Bridge Inventory, including 9 in poor condition and 0 rated scour-critical. Poor-condition bridges carry about 796 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	26.5%	40.0
Poor-condition traffic exposure	25	16.9% of measured traffic	12.7
Scour-critical bridge share	20	0.0%	0.0
Average age vs national baseline	10	54 years vs 48 nationally	2.5
Traffic-data completeness	5	4,709 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	26.5%
State Poor-Condition Share	16.1%
National Poor-Condition Share	6.7%
County Scour-Critical Share	0.0%
Average Bridge Age	54 years
Poor-Condition Traffic Exposure	796 vehicles/day

Bridges to Watch

Busiest Poor-Condition Bridge425th Avenue over Burlington Northern Rr — 274 vehicles/day Oldest Listed Bridge412th Avenue over Creek — built in 1920 All County BridgesBrowse every bridge record in Day County.

Top Bridges to Watch in Day County

Bridge	Reason	Condition	Daily Traffic	Year Built
425th Avenue over Burlington Northern Rr	Poor condition + traffic exposure	Poor	274	1960
423rd Avenue over Burlington Northern Rr	Poor condition + traffic exposure	Poor	218	1938
137th Street over Creek	Poor condition + traffic exposure	Poor	115	1926
12590-416th Avenue over Ck	Poor condition + traffic exposure	Poor	70	1932
412th Avenue over Creek	Poor condition + traffic exposure	Poor	69	1920
418th Avenue over Antelope Creek	Poor condition + traffic exposure	Poor	15	1928
127th Street over Creek	Poor condition + traffic exposure	Poor	15	1930
133rd Street over Creek	Poor condition + traffic exposure	Poor	10	1935
421st Avenue over Antelope Creek	Poor condition + traffic exposure	Poor	10	1935
446a Avenue over Blue Dog Lake	High traffic	Good	852	2023

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.