US Bridges

Ill 161 over Overflow Silver CR

Fair

St. Clair County, Illinois · 1.8 M E Ill 158 · Structure no. 082009400000000

Built
1932
93 years old, rebuilt 1980
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
126 ft
3 main spans
Daily traffic
4,950
2023 count
Owner
State
State Highway Agency

About this bridge

Ill 161 over Overflow Silver CR is a steel continuous stringer/multi-beam or girder carrying Ill 161 over Overflow Silver CR in St. Clair County, Illinois. It was built in 1932 and reconstructed in 1980, so it is 93 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 4,950 vehicles a day, roughly 9% of them trucks, projected to reach 5,404 by 2046. The structure is 126 ft (38.3 m) long and 35 ft wide. If it were closed, the detour would be 9.9 mi (16 km).

Location

Open in Google Maps
CarriesIll 161
CrossesOverflow Silver CR
Location1.8 M E Ill 158
RouteState Highway 161
CountySt. Clair County
StateIllinois
Coordinates38.52549, -89.83396
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
Deck7 GoodSome minor problems.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating38.6 US tons
Inventory rating27.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length126 ft (38.3 m)
Longest span41 ft (12.6 m)
Deck width35 ft (10.7 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,950 (2023)
Projected traffic5,404 by 2046
Trucks9%
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 Ill 161 over Overflow Silver CR built?

It was built in 1932, making it 93 years old in 2025. It was reconstructed in 1980.

What condition is Ill 161 over Overflow Silver CR 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 April 2023.

How much traffic does Ill 161 over Overflow Silver CR carry?

About 4,950 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is Ill 161 over Overflow Silver CR?

The structure is 126 ft (38.3 m) long with a longest span of 41 ft (12.6 m) and a deck 35 ft wide.

Who owns Ill 161 over Overflow Silver CR?

It is owned by the State Highway Agency.