US Bridges

15th Ave over Rock River

Poor

Winnebago County, Illinois · 0.01 M E of Main · Structure no. 101613700000000

Built
1980
45 years old
Condition
Poor
inspected July 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
529 ft
8 main spans
Daily traffic
5,750
2022 count
Owner
City
City or Municipal Highway Agency

About this bridge

15th Ave over Rock River is a steel stringer/multi-beam or girder carrying 15th Ave over Rock River in Winnebago County, Illinois. It was built in 1980, so it is 45 years old, younger than the Illinois average of 45.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 5,750 vehicles a day, roughly 11% of them trucks, projected to reach 6,969 by 2046. The structure is 529 ft (161.2 m) long and 76 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
Carries15th Ave
CrossesRock River
Location0.01 M E of Main
CountyWinnebago County
StateIllinois
Coordinates42.25106, -89.10311
Functional classUrban Minor Arterial

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating68.6 US tons
Inventory rating41.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans8
Design loadHS 20
Structure length529 ft (161.2 m)
Longest span69 ft (21 m)
Deck width76 ft (23.2 m)
Roadway width54 ft (16.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,750 (2022)
Projected traffic6,969 by 2046
Trucks11%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal 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 15th Ave over Rock River built?

It was built in 1980, making it 45 years old in 2025.

What condition is 15th Ave over Rock River in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in July 2023.

How much traffic does 15th Ave over Rock River carry?

About 5,750 vehicles per day (2022 count), of which roughly 11% are trucks.

How long is 15th Ave over Rock River?

The structure is 529 ft (161.2 m) long with a longest span of 69 ft (21 m) and a deck 76 ft wide.

Who owns 15th Ave over Rock River?

It is owned by the City or Municipal Highway Agency.