Structure 900 · Des Moines County, IA

So Main ST over Cascade Landing

Carries So Main ST over Cascade Landing, 000000000.

Overall conditionPoor

Set by its lowest-rated component: Superstructure at 2 of 9.

How ratings work
Deck7/9 · Good
Superstructuresets the rating2/9 · Critical
Substructure5/9 · Fair
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT464 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 2/9 · sets the ratingSubstructure 5/9

464 ft end to end, longest span 160 ft: about 6 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 deck truss.

Built1896rebuilt 1960
Length463.9 ft141.4 m
Daily traffic743counted 2022
Last inspectedAugust 2008every 24 months

Location

StateIowa
CountyDes Moines
Location000000000
CarriesSo Main ST
CrossesCascade Landing
Coordinates40.78111, -91.09861

Physical Characteristics

MaterialSteel
DesignTruss - Deck
Total Length463.9 ft (141.4 m)
Max Span160.1 ft (48.8 m)
Deck Width40.0 ft (12.2 m)
Deck Area1725.1 sq m
Main Spans4
Year Built1896 (reconstructed 1960)

Traffic

Avg Daily Traffic743 (2022)
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2008
Inspection FrequencyEvery 24 months
OwnerCity/Municipal Highway Agency
Historical SignificanceBridge is on the National Register of Historic Places
Scour Critical9 — Foundation above flood level
Structure Number000000000000900

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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