Structure 284421 · Pottawattamie County, IA

300th Street over Middle Silver Creek

Carries 300th Street over Middle Silver Creek, 074411902.

Overall conditionGood

Set by its lowest-rated component: Deck and Substructure at 7 of 9.

How ratings work
Decksets the rating7/9 · Good
Superstructure8/9 · Very Good
Substructuresets the rating7/9 · Good
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT231 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9 · sets the ratingSuperstructure 8/9Substructure 7/9 · sets the rating

231 ft end to end, longest span 80 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.

Built200323 years old
Length231.0 ft70.4 m
Daily traffic79counted 2022
Last inspectedJuly 2023every 48 months

Location

StateIowa
CountyPottawattamie
Location074411902
Carries300th Street
CrossesMiddle Silver Creek
Coordinates41.19628, -95.61295

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length231.0 ft (70.4 m)
Max Span80.1 ft (24.4 m)
Deck Width27.2 ft (8.3 m)
Deck Area584.3 sq m
Main Spans3
Year Built2003

Traffic

Avg Daily Traffic79 (2022)
Lanes On Bridge2

Inspection & Ownership

Last InspectionJuly 2023
Inspection FrequencyEvery 48 months
OwnerCounty Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number000000000284421

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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