US Bridges

I-55 over Three Mile Branch

Fair

Montgomery County, Illinois · 2M S Il 108 · Structure no. 068201600000000

Built
1973
52 years old
Condition
Fair
inspected March 2024
Type
Culvert
Concrete
Length
34 ft
3 main spans
Daily traffic
26,500
2023 count
Owner
State
State Highway Agency

About this bridge

I-55 over Three Mile Branch is a concrete culvert carrying I-55 over Three Mile Branch in Montgomery 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 26,500 vehicles a day, roughly 32% of them trucks, projected to reach 25,856 by 2046. The structure is 34 ft (10.4 m) long. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI-55
CrossesThree Mile Branch
Location2M S Il 108
RouteInterstate 55
CountyMontgomery County
StateIllinois
Coordinates39.24922, -89.64119
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
Channel and channel protection7 GoodSome minor problems.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating91.8 US tons
Inventory rating55 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans3
Design loadHS 20
Structure length34 ft (10.4 m)
Longest span10 ft (3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26,500 (2023)
Projected traffic25,856 by 2046
Trucks32%
Lanes on structure6
Traffic directionTwo-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 over Three Mile Branch built?

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

What condition is I-55 over Three Mile Branch 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 March 2024.

How much traffic does I-55 over Three Mile Branch carry?

About 26,500 vehicles per day (2023 count), of which roughly 32% are trucks.

How long is I-55 over Three Mile Branch?

The structure is 34 ft (10.4 m) long with a longest span of 10 ft (3 m).

Who owns I-55 over Three Mile Branch?

It is owned by the State Highway Agency.