Structure 604705 · Linn County, IA

SB I-380 over 42nd ST

Carries SB I-380 over 42nd ST, 0.5 Mi. S Of Jct. 100.

Overall conditionFair

Set by its lowest-rated component: Deck at 6 of 9.

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructure7/9 · Good
Substructure7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT191 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 7/9

191 ft end to end, longest span 97 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 multi-beam bridge.

Built198145 years old
Length190.9 ft58.2 m
Daily traffic28,050counted 2022
Last inspectedNovember 2024every 24 months

Location

StateIowa
CountyLinn
Location0.5 Mi. S Of Jct. 100
CarriesSB I-380
Crosses42nd ST
Coordinates42.02174, -91.66887

Physical Characteristics

MaterialPrestressed Concrete
DesignStringer/Multi-beam
Total Length190.9 ft (58.2 m)
Max Span97.1 ft (29.6 m)
Deck Width59.1 ft (18 m)
Deck Area1047.6 sq m
Main Spans3
Year Built1981

Traffic

Avg Daily Traffic28,050 (2022)
Truck Traffic13%
Lanes On Bridge3
Lanes Under Bridge5

Inspection & Ownership

Last InspectionNovember 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number000000000604705

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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