Structure 109661 · Cherokee County, IA

Local 470th ST over Mill Creek

Carries Local 470th ST over Mill Creek, 093403201.

Overall conditionFair

Set by its lowest-rated component: Substructure at 6 of 9.

How ratings work
Deck7/9 · Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT208 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 6/9 · sets the rating

208 ft end to end, longest span 69 ft: about 3 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a multi-beam bridge.

Built197452 years old
Length208.0 ft63.4 m
Daily traffic71counted 2022
Last inspectedAugust 2023every 24 months

Location

StateIowa
CountyCherokee
Location093403201
CarriesLocal 470th ST
CrossesMill Creek
Coordinates42.83739, -95.60007

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length208.0 ft (63.4 m)
Max Span68.9 ft (21 m)
Deck Width25.9 ft (7.9 m)
Deck Area500.9 sq m
Main Spans3
Year Built1974

Traffic

Avg Daily Traffic71 (2022)
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000000000109661

How Bridge Ratings Work

Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."

0Failed
1Imminent failure
2Critical
3Serious
4Poor
5Fair
6Satisfactory
7Good
8Very good
9Excellent
Good · lowest component 7–9
Fair · lowest component 5–6
Poor · lowest component 0–4

A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.

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