US Bridges

Thorne RD over Kiswaukee River

Fair

McHenry County, Illinois · 1.0 MI N. of US-20 · Structure no. 056500700000000

Built
1959
66 years old
Condition
Fair
inspected October 2024
Type
Culvert
Steel
Length
29 ft
4 main spans
Daily traffic
275
2021 count
Owner
Town / Township
Town or Township Highway Agency

About this bridge

Thorne RD over Kiswaukee River is a steel culvert carrying Thorne RD over Kiswaukee River in McHenry County, Illinois. It was built in 1959, so it is 66 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 275 vehicles a day, roughly 13% of them trucks, projected to reach 330 by 2046. The structure is 29 ft (8.8 m) long and 20 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesThorne RD
CrossesKiswaukee River
Location1.0 MI N. of US-20
RouteCounty Highway 0
CountyMcHenry County
StateIllinois
Coordinates42.26498, -88.66465
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
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionOctober 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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36.4 US tons
Inventory rating21.8 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadUnknown
Structure length29 ft (8.8 m)
Longest span6 ft (1.8 m)
Deck width20 ft (6.1 m)
Roadway width18 ft (5.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic275 (2021)
Projected traffic330 by 2046
Trucks13%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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$77,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Thorne RD over Kiswaukee River built?

It was built in 1959, making it 66 years old in 2025.

What condition is Thorne RD over Kiswaukee 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 October 2024.

How much traffic does Thorne RD over Kiswaukee River carry?

About 275 vehicles per day (2021 count), of which roughly 13% are trucks.

How long is Thorne RD over Kiswaukee River?

The structure is 29 ft (8.8 m) long with a longest span of 6 ft (1.8 m) and a deck 20 ft wide.

Who owns Thorne RD over Kiswaukee River?

It is owned by the Town or Township Highway Agency.