Structure 117581 · Clay County, IA

310th ST over Little Sioux River

Carries 310th ST over Little Sioux River, 097372802.

Overall conditionGood

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

How ratings work
Decksets the rating7/9 · Good
Superstructuresets the rating7/9 · 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 FT223 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 7/9Superstructure 7/9Substructure 7/9

223 ft end to end, longest span 49 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 slab bridge.

Built198640 years old
Length223.1 ft68 m
Daily traffic81counted 2022
Last inspectedDecember 2022every 48 months

Location

StateIowa
CountyClay
Location097372802
Carries310th ST
CrossesLittle Sioux River
Coordinates43.19794, -95.22929

Physical Characteristics

MaterialConcrete Continuous
DesignSlab
Total Length223.1 ft (68 m)
Max Span48.9 ft (14.9 m)
Deck Width32.2 ft (9.8 m)
Deck Area666.4 sq m
Main Spans5
Year Built1986

Traffic

Avg Daily Traffic81 (2022)
Lanes On Bridge2

Inspection & Ownership

Last InspectionDecember 2022
Inspection FrequencyEvery 48 months
OwnerCounty Highway Agency
Historical SignificanceBridge is possibly eligible (requires evaluation)
Scour Critical8 — Stable, low risk
Structure Number000000000117581

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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