Structure 68004300000000 · Montgomery County, IL

Il 108 over I-55

Carries Il 108 over I-55, Il 108/i-55 Interch..

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 FT262 FT OVERALL50 FT0ELEVATION · LENGTHS TO SCALE
Deck 6/9 · sets the ratingSuperstructure 7/9Substructure 7/9

262 ft end to end, longest span 99 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.

Built197353 years old
Length262.1 ft79.9 m
Daily traffic2,000counted 2023
Last inspectedJune 2023every 24 months

Location

StateIllinois
CountyMontgomery
LocationIl 108/i-55 Interch.
CarriesIl 108
CrossesI-55
Coordinates39.27808, -89.64223

Physical Characteristics

MaterialSteel Continuous
DesignStringer/Multi-beam
Total Length262.1 ft (79.9 m)
Max Span98.8 ft (30.1 m)
Deck Width68.2 ft (20.8 m)
Deck Area1661.9 sq m
Main Spans2
Year Built1973

Traffic

Avg Daily Traffic2,000 (2023)
Truck Traffic14%
Lanes On Bridge2
Lanes Under Bridge4

Inspection & Ownership

Last InspectionJune 2023
Inspection FrequencyEvery 24 months
OwnerState Highway Agency
Historical SignificanceBridge is not eligible for the National Register
Scour CriticalNot applicable
Structure Number068004300000000

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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