US Bridges

Il 173 over Des Plaines River

Good

Lake County, Illinois · 0.2 M E of US 41 · Structure no. 049005900000000

Built
1929
96 years old, rebuilt 2011
Condition
Good
inspected July 2021
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
114 ft
3 main spans
Daily traffic
11,200
2023 count
Owner
State
State Highway Agency

About this bridge

Il 173 over Des Plaines River is a prestressed concrete box beam or girders - multiple carrying Il 173 over Des Plaines River in Lake County, Illinois. It was built in 1929 and reconstructed in 2011, so it is 96 years old, older than the Illinois average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 11,200 vehicles a day, roughly 5% of them trucks, projected to reach 10,504 by 2046. The structure is 114 ft (34.7 m) long and 41 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesIl 173
CrossesDes Plaines River
Location0.2 M E of US 41
RouteState Highway 173
CountyLake County
StateIllinois
Coordinates42.46536, -87.94288
Functional classUrban Other Principal Arterial

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2021
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than 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 alignment7: Better than present minimum criteria
Operating rating69.7 US tons
Inventory rating53.6 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length114 ft (34.7 m)
Longest span38 ft (11.6 m)
Deck width41 ft (12.5 m)
Roadway width40 ft (12.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,200 (2023)
Projected traffic10,504 by 2046
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed9.9 mi (16 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Il 173 over Des Plaines River built?

It was built in 1929, making it 96 years old in 2025. It was reconstructed in 2011.

What condition is Il 173 over Des Plaines River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in July 2021.

How much traffic does Il 173 over Des Plaines River carry?

About 11,200 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is Il 173 over Des Plaines River?

The structure is 114 ft (34.7 m) long with a longest span of 38 ft (11.6 m) and a deck 41 ft wide.

Who owns Il 173 over Des Plaines River?

It is owned by the State Highway Agency.