US Bridges

I-155 NB over I-55 SB

Fair

Logan County, Illinois · I-55/155 NW Lincoln · Structure no. 054005000000000

Built
1973
52 years old
Condition
Fair
inspected January 2025
Type
Stringer/Multi-beam or Girder
Steel
Length
194 ft
1 main span
Daily traffic
5,300
2023 count
Owner
State
State Highway Agency

About this bridge

I-155 NB over I-55 SB is a steel stringer/multi-beam or girder carrying I-155 NB over I-55 SB in Logan 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 5,300 vehicles a day, roughly 19% of them trucks, projected to reach 5,300 by 2046. The structure is 194 ft (59.1 m) long and 42 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-155 NB
CrossesI-55 SB
LocationI-55/155 NW Lincoln
RouteInterstate 155
CountyLogan County
StateIllinois
Coordinates40.17812, -89.4159
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJanuary 2025
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 rating58.2 US tons
Inventory rating35.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHS 20 + Mod
Structure length194 ft (59.1 m)
Longest span114 ft (34.8 m)
Deck width42 ft (12.8 m)
Roadway width38 ft (11.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,300 (2023)
Projected traffic5,300 by 2046
Trucks19%
Lanes on structure2
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 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-155 NB over I-55 SB built?

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

What condition is I-155 NB over I-55 SB 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 2025.

How much traffic does I-155 NB over I-55 SB carry?

About 5,300 vehicles per day (2023 count), of which roughly 19% are trucks.

How long is I-155 NB over I-55 SB?

The structure is 194 ft (59.1 m) long with a longest span of 114 ft (34.8 m) and a deck 42 ft wide.

Who owns I-155 NB over I-55 SB?

It is owned by the State Highway Agency.