Structure 15005600000000 · Coles County, IL

Fas 661(ch 20) over Kaskaskia River

Carries Fas 661(ch 20) over Kaskaskia River, N Of Cooks Mills.

Overall conditionFair

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

How ratings work
Decksets the rating6/9 · Satisfactory
Superstructuresets the rating6/9 · Satisfactory
Substructure7/9 · Good
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT279 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 6/9 · sets the ratingSubstructure 7/9

279 ft end to end, longest span 76 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.

Built1937rebuilt 1981
Length278.9 ft85 m
Daily traffic600counted 2024
Last inspectedJanuary 2025every 24 months

Location

StateIllinois
CountyColes
LocationN Of Cooks Mills
CarriesFas 661(ch 20)
CrossesKaskaskia River
Coordinates39.58323, -88.41357

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length278.9 ft (85 m)
Max Span76.1 ft (23.2 m)
Deck Width33.1 ft (10.1 m)
Deck Area858.5 sq m
Main Spans4
Year Built1937 (reconstructed 1981)

Traffic

Avg Daily Traffic600 (2024)
Truck Traffic10%
Lanes On Bridge2

Inspection & Ownership

Last InspectionJanuary 2025
Inspection FrequencyEvery 24 months
OwnerCounty Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number015005600000000

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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