US Bridges

Il 171 over I-355

Fair

Will County, Illinois · 0.62 M S of 139th ST · Structure no. 099033300000000

Built
2007
18 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
322 ft
2 main spans
Daily traffic
11,500
2023 count
Owner
State
State Highway Agency

About this bridge

Il 171 over I-355 is a prestressed concrete continuous stringer/multi-beam or girder carrying Il 171 over I-355 in Will County, Illinois. It was built in 2007, so it is 18 years old, younger 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 11,500 vehicles a day, roughly 12% of them trucks, projected to reach 17,856 by 2046. The structure is 322 ft (98.2 m) long and 101 ft wide.

Location

Open in Google Maps
CarriesIl 171
CrossesI-355
Location0.62 M S of 139th ST
RouteState Highway 171
CountyWill County
StateIllinois
Coordinates41.63245, -88.01471
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating72.5 US tons
Inventory rating43.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans2 (+2 approach)
Design loadHS 20
Structure length322 ft (98.2 m)
Longest span132 ft (40.2 m)
Deck width101 ft (30.8 m)
Roadway width97 ft (29.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,500 (2023)
Projected traffic17,856 by 2046
Trucks12%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
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 proposedNone recorded
Estimated improvement cost—
NavigationNot applicable (no waterway)

Frequently asked questions

When was Il 171 over I-355 built?

It was built in 2007, making it 18 years old in 2025.

What condition is Il 171 over I-355 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 August 2023.

How much traffic does Il 171 over I-355 carry?

About 11,500 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is Il 171 over I-355?

The structure is 322 ft (98.2 m) long with a longest span of 132 ft (40.2 m) and a deck 101 ft wide.

Who owns Il 171 over I-355?

It is owned by the State Highway Agency.