US Bridges

I-55 NB over US 51B (main St)

Fair

McLean County, Illinois · Inter I 55 & US 51B · Structure no. 057002400000000

Built
1962
63 years old, rebuilt 2010
Condition
Fair
inspected February 2025
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
210 ft
4 main spans
Daily traffic
15,750
2023 count
Owner
State
State Highway Agency

About this bridge

I-55 NB over US 51B (main St) is a steel continuous stringer/multi-beam or girder carrying I-55 NB over US 51B (main St) in McLean County, Illinois. It was built in 1962 and reconstructed in 2010, so it is 63 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 15,750 vehicles a day, roughly 27% of them trucks, projected to reach 14,645 by 2046. The structure is 210 ft (63.9 m) long and 81 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-55 NB
CrossesUS 51B (main St)
LocationInter I 55 & US 51B
RouteInterstate 55
CountyMcLean County
StateIllinois
Coordinates40.53882, -88.99634
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionFebruary 2025
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 rating75 US tons
Inventory rating45 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20 + Mod
Structure length210 ft (63.9 m)
Longest span57 ft (17.4 m)
Deck width81 ft (24.7 m)
Roadway width78 ft (23.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic15,750 (2023)
Projected traffic14,645 by 2046
Trucks27%
Lanes on structure3
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
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-55 NB over US 51B (main St) built?

It was built in 1962, making it 63 years old in 2025. It was reconstructed in 2010.

What condition is I-55 NB over US 51B (main St) 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 February 2025.

How much traffic does I-55 NB over US 51B (main St) carry?

About 15,750 vehicles per day (2023 count), of which roughly 27% are trucks.

How long is I-55 NB over US 51B (main St)?

The structure is 210 ft (63.9 m) long with a longest span of 57 ft (17.4 m) and a deck 81 ft wide.

Who owns I-55 NB over US 51B (main St)?

It is owned by the State Highway Agency.