US Bridges

I-355 SB over US 20

Fair

DuPage County, Illinois · 1.5 M S Il 19 · Structure no. 022011100000000

Built
1970
55 years old, rebuilt 1988
Condition
Fair
inspected November 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
187 ft
3 main spans
Daily traffic
70,250
2023 count
Owner
State
State Highway Agency

About this bridge

I-355 SB over US 20 is a steel continuous stringer/multi-beam or girder carrying I-355 SB over US 20 in DuPage County, Illinois. It was built in 1970 and reconstructed in 1988, so it is 55 years old, older than the Illinois average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 70,250 vehicles a day, roughly 10% of them trucks, projected to reach 54,641 by 2046. The structure is 187 ft (56.9 m) long and 61 ft wide.

Location

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CarriesI-355 SB
CrossesUS 20
Location1.5 M S Il 19
RouteInterstate 355
CountyDuPage County
StateIllinois
Coordinates41.95162, -88.03486
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating56.8 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length187 ft (56.9 m)
Longest span96 ft (29.3 m)
Deck width61 ft (18.5 m)
Roadway width58 ft (17.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic70,250 (2023)
Projected traffic54,641 by 2046
Trucks10%
Lanes on structure3
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed—
TollOn a toll road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I-355 SB over US 20 built?

It was built in 1970, making it 55 years old in 2025. It was reconstructed in 1988.

What condition is I-355 SB over US 20 in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2023.

How much traffic does I-355 SB over US 20 carry?

About 70,250 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is I-355 SB over US 20?

The structure is 187 ft (56.9 m) long with a longest span of 96 ft (29.3 m) and a deck 61 ft wide.

Who owns I-355 SB over US 20?

It is owned by the State Highway Agency.