When will construction begin?
Construction is expected to begin Summer/Fall 2023.
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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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.
The traffic separator on Karcher Road near Sundance Road will be extended to Cassia Street to address safety concerns with widening Karcher Road. Left hand turns along this stretch of Karcher will be restricted.
To view a detailed map of the design plans, please click this link.
Community Involvement
ITD hosted an in-person Public Open House on July 7, 2022 with a one-week window for online participation.
- 139 people attended in person
- 260 people participated online
Public participation and input are crucial to the design process. Feedback given at the open house was incorporated into the final design.”
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.
Downloads & Resources
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?
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.