US Bridges

IH 39 NB over Rock River

Good

Rock County, Wisconsin · 21 M N JCT IH 43 · Structure no. B53035800000000

Built
2016
9 years old
Condition
Good
inspected September 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
718 ft
6 main spans
Daily traffic
26,750
2022 count
Owner
State
State Highway Agency

About this bridge

IH 39 NB over Rock River is a prestressed concrete continuous stringer/multi-beam or girder carrying IH 39 NB over Rock River in Rock County, Wisconsin. It was built in 2016, so it is 9 years old, younger than the Wisconsin average of 40.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 26,750 vehicles a day, roughly 29% of them trucks, projected to reach 32,100 by 2042. The structure is 718 ft (218.9 m) long and 63 ft wide.

Location

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CarriesIH 39 NB
CrossesRock River
Location21 M N JCT IH 43
RouteInterstate 0
CountyRock County
StateWisconsin
Coordinates42.82833, -89.02556
Functional classRural Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation8: Equal to present desirable criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50.4 US tons
Inventory rating38.9 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckNot applicable
Main spans6
Design loadHL 93
Structure length718 ft (218.9 m)
Longest span128 ft (39 m)
Deck width63 ft (19.2 m)
Roadway width36 ft (11 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26,750 (2022)
Projected traffic32,100 by 2042
Trucks29%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway and waterway
Detour if closed—
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState 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$4.2 million (2024 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was IH 39 NB over Rock River built?

It was built in 2016, making it 9 years old in 2025.

What condition is IH 39 NB over Rock River in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in September 2023.

How much traffic does IH 39 NB over Rock River carry?

About 26,750 vehicles per day (2022 count), of which roughly 29% are trucks.

How long is IH 39 NB over Rock River?

The structure is 718 ft (218.9 m) long with a longest span of 128 ft (39 m) and a deck 63 ft wide.

Who owns IH 39 NB over Rock River?

It is owned by the State Highway Agency.