US Bridges

Chestnut ST over Rock River

Fair

Winnebago County, Illinois · 0.1 MI E of Main ST · Structure no. 101613300000000

Built
1962
63 years old, rebuilt 1998
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
448 ft
4 main spans
Daily traffic
8,200
2023 count
Owner
State
State Highway Agency

About this bridge

Chestnut ST over Rock River is a steel continuous stringer/multi-beam or girder carrying Chestnut ST over Rock River in Winnebago County, Illinois. It was built in 1962 and reconstructed in 1998, so it is 63 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 8,200 vehicles a day, roughly 3% of them trucks, projected to reach 6,868 by 2046. The structure is 448 ft (136.6 m) long and 64 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesChestnut ST
CrossesRock River
Location0.1 MI E of Main ST
RouteU.S. Route 20
CountyWinnebago County
StateIllinois
Coordinates42.2689, -89.09402
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
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 rating72.5 US tons
Inventory rating43.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length448 ft (136.6 m)
Longest span111 ft (33.8 m)
Deck width64 ft (19.5 m)
Roadway width52 ft (15.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,200 (2023)
Projected traffic6,868 by 2046
Trucks3%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was Chestnut ST over Rock River built?

It was built in 1962, making it 63 years old in 2025. It was reconstructed in 1998.

What condition is Chestnut ST over Rock 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 Chestnut ST over Rock River carry?

About 8,200 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is Chestnut ST over Rock River?

The structure is 448 ft (136.6 m) long with a longest span of 111 ft (33.8 m) and a deck 64 ft wide.

Who owns Chestnut ST over Rock River?

It is owned by the State Highway Agency.