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I-84, Karcher Interchange Improvements (2022)

Improvements to the Karcher Interchange will provide an additional westbound lane across the interchange and through Caldwell Blvd. These updates will reduce congestion and enhance safety.

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Project Update

Thank you to everyone who participated in our online and in-person open house between July 7 – 14, 2022. The project team will review comments and input submitted by community members and make plans for next steps in the project. Materials and information from the open house are available in the Downloads & Resources section below.

Improvements Include:

  • Re-configuring westbound and eastbound off-ramps to improve safety and traffic flow.
  • Expanding the interchange bridge to provide a dedicated lane for the westbound off-ramp traffic to enter.
  • Adding a westbound lane on SH-55 between Caldwell Blvd to Sundance Rd.
  • Repaving roadway surfaces throughout the project.
  • Adjustments to signals at ramp intersections, Caldwell Blvd and Cassia St to accommodate SH-55  pavement widening.
  • Installing a pedestrian flashing beacon at the eastbound on-ramp.
  • Widening some sidewalks within project limits.

 

Community Involvement

ITD will provide several opportunities for the public to comment on improvements to the Karcher Interchange.

Public participation and input are crucial to the design process. Feedback given at the open house may influence the final design and help decide how traffic is managed during construction.

Safety Benefits

Improving the Karcher Interchange will eliminate queuing on the westbound off-ramp, allow for better flow of traffic on SH-55, and reduce sideswipe crashes by allowing longer merging distances. With an additional westbound lane on SH-55, drivers wouldn’t need to make last-minute, unpredictable lane changes to jockey for better positioning.

Sidewalks improvements are being incorporated to better align with Nampa’s Master Bike and Pedestrian Plan. Buffer zones will separate bikes and pedestrians from the street. Cyclists and pedestrians can expect greater visibility with the addition of a pedestrian flashing beacon at the eastbound on-ramp. Drivers will be able to see an advanced pedestrian flashing beacon to allow for a better response time in slowing down for crossing pedestrians.

Funding

This design is being funded with Transportation Expansion and Congestion Mitigation (TECM) funds as part of Governor Little’s Leading Idaho initiative. The program allows ITD to accelerate project timelines to address rapid growth and build critical infrastructure today that would otherwise take many years to fund and build.

The I-84 corridor is one of 13 approved TECM corridors in the state. Funding for the construction phases on this corridor will be determined based on project readiness and funding availability.

Preliminary estimates value the improvements needed in this corridor at $20 million to $25 million, which includes design, right-of-way and construction costs. Work will be completed in one season once funding in secured.

 

Working

**All contact information will be kept confidential,
but all comments will be publicly visible**
Interactive Comment Map

Click on map to place comment.

View Map
Winter 2021/Spring 2022
Field work and design process begins
Summer 2022
Gather public input
Fall 2022
Design plans finalized
Winter 2022
Purchase right-of-way
Early Spring 2023
Prepare construction plans
Frequently Asked Questions
You've got questions, we've got answers! Here are some of the most common questions we've received about this project.
When will construction begin?
When will construction begin?

Funding for construction is not yet identified, however ITD will be ready with a construction plan set in Spring 2023.

What are the current and projected traffic volumes?
What are the current and projected traffic volumes?

Current interchange traffic volumes, or “ADTs” (Average Daily Trips), are estimated at 47,959 vehicles per day. It is expected that this number will reach 69,417 by 2045.

Will the proposed improvements help with “traffic stacking” on I-84 at the westbound off-ramp?
Will the proposed improvements help with “traffic stacking” on I-84 at the westbound off-ramp?

Yes, the Karcher Interchange westbound off-ramp free running right entering into a dedicated lane across the interchange, and signal improvements are expected to reduce the traffic stacking that occurs on I-84. The new lane will give traffic additional space, while the signal improvements and free-running right will improve traffic flow onto State Highway 55.

Will ITD improve any bicycle or pedestrian facilities as a part of this project?
Will ITD improve any bicycle or pedestrian facilities as a part of this project?

Yes, a new pedestrian flashing beacon will be installed at the Karcher Interchange eastbound on-ramp.  Sidewalks on the north side of State Highway 55 between Middleton Road and Caldwell Blvd will be widened, as well as the sidewalks on the south side of SH-55 between Caldwell Blvd and the westbound Karcher Interchange on-ramp.

Were there any meetings or public open houses?
Were there any meetings or public open houses?

Yes, an open house took place Summer of 2022. It was an opportunity to learn more about the project and the preliminary designs, and also provided feedback to ITD. Public participation and input are crucial to the design process. Feedback given at the public meeting may influence the final design and help decide how traffic is managed during construction.

Why is ITD widening westbound ramps and southbound lanes, but not eastbound ramps or other spots?
Why is ITD widening westbound ramps and southbound lanes, but not eastbound ramps or other spots?

The decision to widen westbound ramps and southbound lanes was based on the I-84 Traffic Analysis conducted in 2018. The goal was to eliminate queuing on mainline I-84 due to insufficient storage and to optimize signal operations on Karcher Road.

Why does the additional westbound Karcher lane only go to Sundance Road and not all the way to Middleton Road?
Why does the additional westbound Karcher lane only go to Sundance Road and not all the way to Middleton Road?

The new westbound lane on Karcher Road is designed to provide traffic coming off the I-84 westbound interstate ramp a dedicated lane to head towards Caldwell Boulevard. The third westbound lane will taper back into two thru lanes beyond the curve to provide for a safe merge into the through lane.

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