Structure 99000900000000 · Will County, IL

I- 55 NB over Des Plaines River

Carries I- 55 NB over Des Plaines River, 2.3 M S Of US 6.

Overall conditionFair

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

How ratings work
Decksets the rating5/9 · Fair
Superstructuresets the rating5/9 · Fair
Substructuresets the rating5/9 · Fair
Channelnot part of overall7/9 · Good
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT1,406 FT OVERALL250 FT0ELEVATION · LENGTHS TO SCALE
Deck 5/9Superstructure 5/9Substructure 5/9

1,406 ft end to end, longest span 486 ft: about 3.9 football fields. 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 through truss.

Built1957rebuilt 2002
Length1405.8 ft428.5 m
Daily traffic31,250counted 2024
Last inspectedAugust 2023every 24 months

Location

StateIllinois
CountyWill
Location2.3 M S Of US 6
CarriesI- 55 NB
CrossesDes Plaines River
Coordinates41.42004, -88.19436

Physical Characteristics

MaterialSteel Continuous
DesignTruss - Thru
Total Length1405.8 ft (428.5 m)
Max Span485.9 ft (148.1 m)
Deck Width35.8 ft (10.9 m)
Deck Area4670.6 sq m
Main Spans3
Year Built1957 (reconstructed 2002)

Traffic

Avg Daily Traffic31,250 (2024)
Truck Traffic5%
Lanes On Bridge2

Inspection & Ownership

Last InspectionAugust 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number099000900000000

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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