US Bridges

I-55 (nb) over Illinois Central RR

Fair

Sangamon County, Illinois · 1M N Glenarm Intchg · Structure no. 084011200000000

Built
1971
54 years old, rebuilt 1979
Condition
Fair
inspected May 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
340 ft
2 main spans
Daily traffic
17,850
2023 count
Owner
State
State Highway Agency

About this bridge

I-55 (nb) over Illinois Central RR is a steel continuous stringer/multi-beam or girder carrying I-55 (nb) over Illinois Central RR in Sangamon County, Illinois. It was built in 1971 and reconstructed in 1979, so it is 54 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 17,850 vehicles a day, roughly 25% of them trucks, projected to reach 17,978 by 2046. The structure is 340 ft (103.6 m) long and 58 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI-55 (nb)
CrossesIllinois Central RR
Location1M N Glenarm Intchg
RouteInterstate 55
CountySangamon County
StateIllinois
Coordinates39.63033, -89.64661
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating54.7 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2 (+2 approach)
Design loadHS 20 + Mod
Structure length340 ft (103.6 m)
Longest span110 ft (33.4 m)
Deck width58 ft (17.7 m)
Roadway width54 ft (16.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic17,850 (2023)
Projected traffic17,978 by 2046
Trucks25%
Lanes on structure3
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-55 (nb) over Illinois Central RR built?

It was built in 1971, making it 54 years old in 2025. It was reconstructed in 1979.

What condition is I-55 (nb) over Illinois Central 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 May 2023.

How much traffic does I-55 (nb) over Illinois Central RR carry?

About 17,850 vehicles per day (2023 count), of which roughly 25% are trucks.

How long is I-55 (nb) over Illinois Central RR?

The structure is 340 ft (103.6 m) long with a longest span of 110 ft (33.4 m) and a deck 58 ft wide.

Who owns I-55 (nb) over Illinois Central RR?

It is owned by the State Highway Agency.