Structure 25490 · Fremont County, IA

370 Avenue over E Nishna River Overflow

Carries 370 Avenue over E Nishna River Overflow, 069402908.

Overall conditionPoor

Set by its lowest-rated component: Substructure at 3 of 9.

How ratings work
Deck5/9 · Fair
Superstructure5/9 · Fair
Substructuresets the rating3/9 · Serious
Channelnot part of overall3/9 · Serious
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT253 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9Superstructure 5/9Substructure 3/9 · sets the rating

253 ft end to end, longest span 41 ft: about 4 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.

Built195769 years old
Length253.0 ft77.1 m
Daily traffic771counted 2021
Last inspectedApril 2023every 24 months

Location

StateIowa
CountyFremont
Location069402908
Carries370 Avenue
CrossesE Nishna River Overflow
Coordinates40.74311, -95.47977

Physical Characteristics

MaterialSteel
DesignStringer/Multi-beam
Total Length253.0 ft (77.1 m)
Max Span41.0 ft (12.5 m)
Deck Width27.9 ft (8.5 m)
Deck Area655.4 sq m
Main Spans6
Year Built1957

Traffic

Avg Daily Traffic771 (2021)
Truck Traffic10%
Lanes On Bridge2

Inspection & Ownership

Last InspectionApril 2023
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number000000000025490

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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