Structure 82003900000000 · St. Clair County, IL

Ill 15 over Harding Ditch

Carries Ill 15 over Harding Ditch, 0.3 M W Jct 157.

Overall conditionFair

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

How ratings work
Deck8/9 · Very Good
Superstructure7/9 · Good
Substructuresets the rating6/9 · Satisfactory
Channelnot part of overall6/9 · Satisfactory
0 failed4 poor6 fair9 excellent

Elevation

Side view, colored by inspection rating
SEMI-TRUCK · 72 FT157 FT OVERALL25 FT0ELEVATION · LENGTHS TO SCALE
Deck 8/9Superstructure 7/9Substructure 6/9 · sets the rating

157 ft end to end, longest span 60 ft: about 2 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.

Built1940rebuilt 1984
Length157.2 ft47.9 m
Daily traffic30,000counted 2023
Last inspectedMarch 2024every 24 months

Location

StateIllinois
CountySt. Clair
Location0.3 M W Jct 157
CarriesIll 15
CrossesHarding Ditch
Coordinates38.57014, -90.09423

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length157.2 ft (47.9 m)
Max Span60.0 ft (18.3 m)
Deck Width71.2 ft (21.7 m)
Deck Area1039.4 sq m
Main Spans3
Year Built1940 (reconstructed 1984)

Traffic

Avg Daily Traffic30,000 (2023)
Truck Traffic6%
Lanes On Bridge4

Inspection & Ownership

Last InspectionMarch 2024
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour Critical8 — Stable, low risk
Structure Number082003900000000

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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