I-90 Corridor Study: Washington to SH-41

Feedback and comments from the public collected during our open houses and via the online survey were incorporated into the concept designs where possible.

Currently, the I-90 corridor project’s primary focus is I-90 widening between Post Falls and Coeur d’Alene. Additional projects will be advanced through the design and construction process based on priorities identified in the traffic analysis.

The 15-mile corridor will be prioritized for design and construction as funding is identified. The highest priority section, widening I-90 from SH-41 to Northwest Boulevard, began construction in 2025.

The two design alternatives presented at the November 2022 open houses were again deliberated by the design team with the feedback the public provided. A preferred alternative has not been selected at this time.

As the interstate exists today, if the Idaho side of the freeway widens to three lanes, a bottleneck would be created at the border.

As the project designs are finalized, ITD and the Washington State Department of Transportation will remain in close contact and will coordinate to maximize traveler mobility and safety. No matter the number of lanes on the Washington side, the Idaho side would be widened as it would relieve more congestion points in Idaho.

Priorities for corridor improvements are focused on the urban areas of Coeur d’Alene and Post Falls as this is where traffic is heaviest, and relief is needed the most. In order of current priority, widening I-90 to the Washington state line may be one of the last improvements to be implemented.

A collector-distributor road, or a C-D road, separates freeway through traffic from other vehicles entering or exiting the freeway, making it safer for drivers to enter and exit in congested areas with tightly spaced interchanges.

With a C-D system, rather entering an on-ramp and immediately accessing the freeway, drivers will first enter a parallel roadway that “collects” vehicles from several on-ramps and then rejoins to the freeway at a less-congested area where it is easier to merge. This same parallel roadway also “distributes” traffic to off-ramps.

Collector-distributor roads are proposed from US-95 to Fourth Street and in Alternative B in the Post Falls area.

Yes. Determination of noise walls is a two-part process and falls within both the study (current) and design (next) phases. In our current study phase, ITD will soon begin a noise analysis to determine locations where noise walls are feasible.

If a noise wall is shown to be feasible in the study phase, ITD is required in the design phase to ballot the benefited recipients to determine whether the noise wall is desirable to construct. When the noise wall analysis is complete, ITD will proactively notify residents and property owners to share information directly. The noise wall analysis will also be presented at future open houses.

This study 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 corridor is one of 13 approved TECM corridors in the state. Funding for the future design and 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 $1 billion to $1.2 billion in 2022 costs, which includes design, right of way and construction costs. Work will likely be completed in stages over many years.

The new interchange at SH-41 has been in design since October 2017 and was funded for construction when the project was ready to be advertised in 2022. The interchange project was designed to be compatible with anticipated future needs, like expansion.

The goal of this study is to identify capacity and safety improvements on I-90, including geometrics, improved on- and off-ramps, and interchanges needed to accommodate future growth. The study began in 2021 with funding from Leading Idaho.

This study is funded by the Transportation Expansion and Congestion Mitigation bonding program, which was established by the Idaho Legislature to allow the department to quickly design projects to address rapid growth and build critical infrastructure today that would otherwise take many years to fund and build.

The study focuses on expanding the interstate, with impacts anticipated to the Centennial Trail as a result of widening. The project team has met with the Centennial Trail Foundation and other advocates of alternative transportation like the City of Coeur d’Alene Walk/Bike Alliance to maintain connectivity.

This study is not scoped to consider light rail or other mass transition options, though the idea of connecting Spokane, Washington, with Coeur d’Alene, Idaho, has been discussed. Ultimately, the state of Idaho provides very minimal dedicated funding for public transportation. With little state funding, required match money for federal opportunities must come from cities, counties, etc. There is no enabling legislation that allows local areas to approve a local funding option that could support the initial capital and ongoing operational costs of light rail.

Significant resources are needed to build light rail or high-capacity transit networks. In the early 2000s Spokane Transit Authority studied light rail, and the report estimated a rail line between Spokane and Liberty Lake to cost $226 million. A more recent study in 2020 by the Community Planning Association of Southwest Idaho, known as COMPASS, estimated that regional rail between Boise and Caldwell would cost $800 million.