US Bridges

I-39 Sb/Us 51SB over B & N RR

Fair

LaSalle County, Illinois · 0.75 MI N of US 34 · Structure no. 050016300000000

Built
1977
48 years old
Condition
Fair
inspected January 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
169 ft
3 main spans
Daily traffic
8,200
2023 count
Owner
State
State Highway Agency

About this bridge

I-39 Sb/Us 51SB over B & N RR is a prestressed concrete stringer/multi-beam or girder carrying I-39 Sb/Us 51SB over B & N RR in LaSalle County, Illinois. It was built in 1977, so it is 48 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 8,200 vehicles a day, roughly 48% of them trucks, projected to reach 9,494 by 2046. The structure is 169 ft (51.5 m) long and 42 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-39 Sb/Us 51SB
CrossesB & N RR
Location0.75 MI N of US 34
RouteInterstate 39
CountyLaSalle County
StateIllinois
Coordinates41.56534, -89.06199
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.7 US tons
Inventory rating27.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length169 ft (51.5 m)
Longest span65 ft (19.8 m)
Deck width42 ft (12.8 m)
Roadway width38 ft (11.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,200 (2023)
Projected traffic9,494 by 2046
Trucks48%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesRailroad
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate 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 B & N RR built?

It was built in 1977, making it 48 years old in 2025.

What condition is I-39 Sb/Us 51SB over B & N RR 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 January 2024.

How much traffic does I-39 Sb/Us 51SB over B & N RR carry?

About 8,200 vehicles per day (2023 count), of which roughly 48% are trucks.

How long is I-39 Sb/Us 51SB over B & N RR?

The structure is 169 ft (51.5 m) long with a longest span of 65 ft (19.8 m) and a deck 42 ft wide.

Who owns I-39 Sb/Us 51SB over B & N RR?

It is owned by the State Highway Agency.