US Bridges

Williamson Rd/Sbi over I-55

Fair

Macoupin County, Illinois · .8M N Staunton Intch · Structure no. 059004400000000

Built
1973
52 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
254 ft
2 main spans
Daily traffic
1,900
2023 count
Owner
State
State Highway Agency

About this bridge

Williamson Rd/Sbi over I-55 is a steel continuous stringer/multi-beam or girder carrying Williamson Rd/Sbi over I-55 in Macoupin 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 1,900 vehicles a day, roughly 3% of them trucks, projected to reach 2,020 by 2046. The structure is 254 ft (77.4 m) long and 46 ft wide.

Location

Open in Google Maps
CarriesWilliamson Rd/Sbi
CrossesI-55
Location.8M N Staunton Intch
RouteCounty Highway 0
CountyMacoupin County
StateIllinois
Coordinates39.03176, -89.75371
Functional classRural Major Collector

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating101.7 US tons
Inventory rating48.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans2 (+2 approach)
Design loadHS 20
Structure length254 ft (77.4 m)
Longest span101 ft (30.8 m)
Deck width46 ft (14 m)
Roadway width43 ft (13 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,900 (2023)
Projected traffic2,020 by 2046
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemNo

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 Williamson Rd/Sbi over I-55 built?

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

What condition is Williamson Rd/Sbi over I-55 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 August 2023.

How much traffic does Williamson Rd/Sbi over I-55 carry?

About 1,900 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is Williamson Rd/Sbi over I-55?

The structure is 254 ft (77.4 m) long with a longest span of 101 ft (30.8 m) and a deck 46 ft wide.

Who owns Williamson Rd/Sbi over I-55?

It is owned by the State Highway Agency.