US Bridges

I-39 Sb/Us 51SB over I-80

Fair

LaSalle County, Illinois · 2.56 MI W of FAS 256 · Structure no. 050017800000000

Built
1979
46 years old
Condition
Fair
inspected March 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
255 ft
2 main spans
Daily traffic
9,300
2023 count
Owner
State
State Highway Agency

About this bridge

I-39 Sb/Us 51SB over I-80 is a prestressed concrete stringer/multi-beam or girder carrying I-39 Sb/Us 51SB over I-80 in LaSalle County, Illinois. It was built in 1979, so it is 46 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 9,300 vehicles a day, roughly 44% of them trucks, projected to reach 9,141 by 2046. The structure is 255 ft (77.7 m) long and 56 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesI-39 Sb/Us 51SB
CrossesI-80
Location2.56 MI W of FAS 256
RouteInterstate 39
CountyLaSalle County
StateIllinois
Coordinates41.36778, -89.05908
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 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 rating61.1 US tons
Inventory rating36.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2 (+2 approach)
Design loadHS 20
Structure length255 ft (77.7 m)
Longest span106 ft (32.3 m)
Deck width56 ft (17.1 m)
Roadway width50 ft (15.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,300 (2023)
Projected traffic9,141 by 2046
Trucks44%
Lanes on structure2
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed8.1 mi (13 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkNon-Interstate STRAHNET route

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 I-39 Sb/Us 51SB over I-80 built?

It was built in 1979, making it 46 years old in 2025.

What condition is I-39 Sb/Us 51SB over I-80 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 March 2023.

How much traffic does I-39 Sb/Us 51SB over I-80 carry?

About 9,300 vehicles per day (2023 count), of which roughly 44% are trucks.

How long is I-39 Sb/Us 51SB over I-80?

The structure is 255 ft (77.7 m) long with a longest span of 106 ft (32.3 m) and a deck 56 ft wide.

Who owns I-39 Sb/Us 51SB over I-80?

It is owned by the State Highway Agency.