US Bridges

I-55 NB over Mackinaw River

Fair

McLean County, Illinois · 2 MI SW of Lexington · Structure no. 057016800000000

Built
1973
52 years old
Condition
Fair
inspected May 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
333 ft
3 main spans
Daily traffic
11,900
2023 count
Owner
State
State Highway Agency

About this bridge

I-55 NB over Mackinaw River is a prestressed concrete stringer/multi-beam or girder carrying I-55 NB over Mackinaw River in McLean County, Illinois. It was built in 1973, so it is 52 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 11,900 vehicles a day, roughly 32% of them trucks, projected to reach 11,363 by 2046. The structure is 333 ft (101.5 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-55 NB
CrossesMackinaw River
Location2 MI SW of Lexington
RouteInterstate 55
CountyMcLean County
StateIllinois
Coordinates40.62985, -88.81601
Functional classRural 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.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating85 US tons
Inventory rating52.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3 (+2 approach)
Design loadHS 20 + Mod
Structure length333 ft (101.5 m)
Longest span93 ft (28.3 m)
Deck width42 ft (12.8 m)
Roadway width38 ft (11.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic11,900 (2023)
Projected traffic11,363 by 2046
Trucks32%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
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—
NavigationNo navigation control on waterway

Frequently asked questions

When was I-55 NB over Mackinaw River built?

It was built in 1973, making it 52 years old in 2025.

What condition is I-55 NB over Mackinaw River 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 May 2023.

How much traffic does I-55 NB over Mackinaw River carry?

About 11,900 vehicles per day (2023 count), of which roughly 32% are trucks.

How long is I-55 NB over Mackinaw River?

The structure is 333 ft (101.5 m) long with a longest span of 93 ft (28.3 m) and a deck 42 ft wide.

Who owns I-55 NB over Mackinaw River?

It is owned by the State Highway Agency.