US Bridges

TR 340 over Iroquois River

Fair

Iroquois County, Illinois · 1.25 MI N. US 24 · Structure no. 038373200000000

Built
1912
113 years old
Condition
Fair
inspected September 2023
Type
Tee Beam
Concrete Continuous
Length
178 ft
3 main spans
Daily traffic
200
2022 count
Owner
Town / Township
Town or Township Highway Agency

About this bridge

TR 340 over Iroquois River is a concrete continuous tee beam carrying TR 340 over Iroquois River in Iroquois County, Illinois. It was built in 1912, so it is 113 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 200 vehicles a day, roughly 20% of them trucks, projected to reach 177 by 2046. The structure is 178 ft (54.3 m) long and 18 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

Open in Google Maps
CarriesTR 340
CrossesIroquois River
Location1.25 MI N. US 24
RouteCounty Highway 0
CountyIroquois County
StateIllinois
Coordinates40.79173, -87.65356
Functional classRural Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment2: Basically intolerable, requiring high priority of replacement
Operating rating41.8 US tons
Inventory rating25.4 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadUnknown
Structure length178 ft (54.3 m)
Longest span55 ft (16.8 m)
Deck width18 ft (5.6 m)
Roadway width16 ft (4.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic200 (2022)
Projected traffic177 by 2046
Trucks20%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerTown or Township Highway Agency
Maintained byTown or Township Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$519,000
NavigationNo navigation control on waterway

Frequently asked questions

When was TR 340 over Iroquois River built?

It was built in 1912, making it 113 years old in 2025.

What condition is TR 340 over Iroquois River 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 September 2023.

How much traffic does TR 340 over Iroquois River carry?

About 200 vehicles per day (2022 count), of which roughly 20% are trucks.

How long is TR 340 over Iroquois River?

The structure is 178 ft (54.3 m) long with a longest span of 55 ft (16.8 m) and a deck 18 ft wide.

Who owns TR 340 over Iroquois River?

It is owned by the Town or Township Highway Agency.