US Bridges

Il 171 SB Rmp I-55 over Des Plaines River

Fair

Cook County, Illinois · 1.5 M SW Il 43 · Structure no. 016102600000000

Built
1964
61 years old, rebuilt 2014
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
688 ft
7 main spans
Daily traffic
10,500
2024 count
Owner
State
State Highway Agency

About this bridge

Il 171 SB Rmp I-55 over Des Plaines River is a steel continuous stringer/multi-beam or girder carrying Il 171 SB Rmp I-55 over Des Plaines River in Cook County, Illinois. It was built in 1964 and reconstructed in 2014, so it is 61 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 5 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 10,500 vehicles a day, roughly 11% of them trucks, projected to reach 10,100 by 2046. The structure is 688 ft (209.6 m) long and 29 ft wide.

Location

Open in Google Maps
CarriesIl 171 SB Rmp I-55
CrossesDes Plaines River
Location1.5 M SW Il 43
CountyCook County
StateIllinois
Coordinates41.79384, -87.8248
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating87.9 US tons
Inventory rating49.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans7
Design loadHS 20
Structure length688 ft (209.6 m)
Longest span102 ft (31.1 m)
Deck width29 ft (8.9 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic10,500 (2024)
Projected traffic10,100 by 2046
Trucks11%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed—
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2.4 million
NavigationNo navigation control on waterway

Frequently asked questions

When was Il 171 SB Rmp I-55 over Des Plaines River built?

It was built in 1964, making it 61 years old in 2025. It was reconstructed in 2014.

What condition is Il 171 SB Rmp I-55 over Des Plaines River 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 May 2024.

How much traffic does Il 171 SB Rmp I-55 over Des Plaines River carry?

About 10,500 vehicles per day (2024 count), of which roughly 11% are trucks.

How long is Il 171 SB Rmp I-55 over Des Plaines River?

The structure is 688 ft (209.6 m) long with a longest span of 102 ft (31.1 m) and a deck 29 ft wide.

Who owns Il 171 SB Rmp I-55 over Des Plaines River?

It is owned by the State Highway Agency.