US Bridges

Il 120 WB over Des Plaines River

Fair

Lake County, Illinois · 2.5 M W of US 41 · Structure no. 049004700000000

Built
1959
66 years old, rebuilt 2024
Condition
Fair
inspected December 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
179 ft
3 main spans
Daily traffic
30,700
2023 count
Owner
State
State Highway Agency

About this bridge

Il 120 WB over Des Plaines River is a steel continuous stringer/multi-beam or girder carrying Il 120 WB over Des Plaines River in Lake County, Illinois. It was built in 1959 and reconstructed in 2024, so it is 66 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 30,700 vehicles a day, roughly 4% of them trucks, projected to reach 15,351 by 2046. The structure is 179 ft (54.7 m) long and 37 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesIl 120 WB
CrossesDes Plaines River
Location2.5 M W of US 41
RouteState Highway 120
CountyLake County
StateIllinois
Coordinates42.34391, -87.94108
Functional classUrban Other Principal Arterial

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck9 ExcellentNo problems noted.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionDecember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating42.5 US tons
Inventory rating32.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length179 ft (54.7 m)
Longest span69 ft (21 m)
Deck width37 ft (11.3 m)
Roadway width34 ft (10.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic30,700 (2023)
Projected traffic15,351 by 2046
Trucks4%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 km)
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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.2 million
NavigationNo navigation control on waterway

Frequently asked questions

When was Il 120 WB over Des Plaines River built?

It was built in 1959, making it 66 years old in 2025. It was reconstructed in 2024.

What condition is Il 120 WB 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 December 2024.

How much traffic does Il 120 WB over Des Plaines River carry?

About 30,700 vehicles per day (2023 count), of which roughly 4% are trucks.

How long is Il 120 WB over Des Plaines River?

The structure is 179 ft (54.7 m) long with a longest span of 69 ft (21 m) and a deck 37 ft wide.

Who owns Il 120 WB over Des Plaines River?

It is owned by the State Highway Agency.