Structure 52951 · Woodbury County, IA

US 20 EB over Little Sioux River

Carries US 20 EB over Little Sioux River, 0.4 Mi. W Of Jct. Ia 31.

Overall conditionFair

Set by its lowest-rated component: Deck at 5 of 9.

How ratings work
Decksets the rating5/9 · Fair
Superstructure8/9 · Very Good
Substructure7/9 · Good
Channelnot part of overall8/9 · Very Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT493 FT OVERALL100 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9 · sets the ratingSuperstructure 8/9Substructure 7/9

493 ft end to end, longest span 122 ft: about 7 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.

Built20179 years old
Length492.8 ft150.2 m
Daily traffic3,250counted 2022
Last inspectedMarch 2024every 24 months

Location

StateIowa
CountyWoodbury
Location0.4 Mi. W Of Jct. Ia 31
CarriesUS 20 EB
CrossesLittle Sioux River
Coordinates42.48231, -95.79427

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length492.8 ft (150.2 m)
Max Span122.0 ft (37.2 m)
Deck Width43.3 ft (13.2 m)
Deck Area1982.6 sq m
Main Spans4
Year Built2017

Traffic

Avg Daily Traffic3,250 (2022)
Truck Traffic26%
Lanes On Bridge2

Inspection & Ownership

Last InspectionMarch 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000000000052951

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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