Structure 600765 · Woodbury County, IA

I 129 over Missouri River & I-29

Carries I 129 over Missouri River & I-29, 0.5 Mi.w.of Jct.29.

Overall conditionFair

Set by its lowest-rated component: Superstructure and Substructure at 5 of 9.

How ratings work
Deck6/9 · Satisfactory
Superstructuresets the rating5/9 · Fair
Substructuresets the rating5/9 · Fair
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT2,607 FT OVERALL500 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9Superstructure 5/9 · sets the ratingSubstructure 5/9 · sets the rating

2,607 ft end to end, longest span 450 ft: about 7.2 football fields. 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 girder bridge.

Built197650 years old
Length2607.0 ft794.6 m
Daily traffic15,800counted 2022
Last inspectedOctober 2023every 24 months

Location

StateIowa
CountyWoodbury
Location0.5 Mi.w.of Jct.29
CarriesI 129
CrossesMissouri River & I-29
Coordinates42.44689, -96.38091

Physical Characteristics

MaterialSteel Continuous
DesignGirder and Floorbeam
Total Length2607.0 ft (794.6 m)
Max Span450.1 ft (137.2 m)
Deck Width85.3 ft (26 m)
Deck Area20659.6 sq m
Main Spans15
Year Built1976

Traffic

Avg Daily Traffic15,800 (2022)
Truck Traffic17%
Lanes On Bridge4
Lanes Under Bridge6

Inspection & Ownership

Last InspectionOctober 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical5 — Stable for scour
Structure Number000000000600765

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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