I-39/Portage County B interchange, Plover, Portage County
The objective of the project is to reconstruct the interchange so it will safely handle current and future traffic volumes. Specific needs identified include:
- Addressing geometric and structural deficiencies on bridges and roadways within the interchange
- Improving safety on northbound I-39 at the County B on-ramp merge point
- Improving traffic operations at the I-39/County B ramp terminal intersections
Other conditions that are contributing to the need for the project:
- A lack of bicycle and pedestrian accommodations along County B
- The Tomorrow River State Trail underneath I-39, north of the County B interchange, is too close to the railroad
Interchange alternatives for consideration
- Diamond interchange with traffic signals
- Interchange with Northbound Entrance Loop
- Diamond interchange with roundabouts
- Diverging Diamond Interchange (DDI)
Preferred interchange alternative
The four interchange alternatives were presented at an October 2015 public involvement meeting. Since that meeting, project staff completed additional analysis, considered public comments, and identified the Diverging Diamond Interchange (DDI) as the preferred alternative.
The DDI alternative will:
- Meet vertical clearance requirements over County B and the railroad with new or reconstructed bridges.
- Address safety considerations by providing a longer northbound entrance-ramp that allows vehicles to reach safe merging speed prior to merging onto I-39.
- Provide acceptable quality of traffic flow and minimize traffic queues.
- Include pedestrian and bicycle accommodations along County B.
- Address the Tomorrow River State Trail proximity to the railroad by reconstruction the I-39 bridges over the railroad and realigning the trail.
Primary reasons for selecting the DDI alternative:
- Provides least vehicle delay for the high-volume movements at the interchange (southbound right turn and eastbound left turn).
- Received the highest number of favorable comments during the fall 2015 public outreach.
- Requires least additional right of way.
- Provides extra vehicle capacity for occasional high-traffic conditions.
Driving the DDI
To learn how to drive the DDI:
Motorists can likely expect the following during construction:
- A minimum of one lane of traffic for northbound I-39.
- Two lanes of traffic for southbound I-39 traffic during peak travel times; some single lane closures during weekdays.
- Ramps may be closed and detoured for limited periods.
- County B may be limited to one lane in each direction with periodic nighttime closures to allow bridge reconstruction.
- Complete environmental document - Fall 2017
- Additional public outreach - 2017/2018
- Real estate acquisition - 2019
- Complete design - Early 2020
- Construction currently scheduled to begin - 2021