US Bridges

US 36(FAP 320) over Lake Decatur

Fair

Macon County, Illinois · In Decatur · Structure no. 058002000000000

Built
1955
70 years old, rebuilt 1987
Condition
Fair
inspected February 2024
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
465 ft
3 main spans
Daily traffic
20,900
2023 count
Owner
State
State Highway Agency

About this bridge

US 36(FAP 320) over Lake Decatur is a steel continuous stringer/multi-beam or girder carrying US 36(FAP 320) over Lake Decatur in Macon County, Illinois. It was built in 1955 and reconstructed in 1987, so it is 70 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 20,900 vehicles a day, roughly 5% of them trucks, projected to reach 22,422 by 2046. The structure is 465 ft (141.7 m) long and 70 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesUS 36(FAP 320)
CrossesLake Decatur
LocationIn Decatur
RouteU.S. Route 36
CountyMacon County
StateIllinois
Coordinates39.83497, -88.91192
Functional classUrban Other Principal Arterial

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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionFebruary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44 US tons
Inventory rating33.6 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length465 ft (141.7 m)
Longest span180 ft (54.8 m)
Deck width70 ft (21.2 m)
Roadway width54 ft (16.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20,900 (2023)
Projected traffic22,422 by 2046
Trucks5%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 36(FAP 320) over Lake Decatur built?

It was built in 1955, making it 70 years old in 2025. It was reconstructed in 1987.

What condition is US 36(FAP 320) over Lake Decatur 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 February 2024.

How much traffic does US 36(FAP 320) over Lake Decatur carry?

About 20,900 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is US 36(FAP 320) over Lake Decatur?

The structure is 465 ft (141.7 m) long with a longest span of 180 ft (54.8 m) and a deck 70 ft wide.

Who owns US 36(FAP 320) over Lake Decatur?

It is owned by the State Highway Agency.