I-90, ID-41 Interchange

Traffic volumes continue to grow, prompting the redesign of the interchange to safely accommodate more drivers.

Redesigning the intersection will involve replacing bridges, realigning on- and off-ramps, providing continued access for cyclists and pedestrians, and constructing capacity for planned and possible expansion. The new design will be a single-point urban interchange (SPUI).

Project updates

Selected design

The team developed this design after the public meeting and property owner contacts in November 2018. As an offset SPUI, it merges the advantages of both the half-diamond interchange and the SPUI previously proposed.

By using one signal, rather than two signals, to control movements, the SPUI design will likely be more efficient and decrease travel times. This design will achieve the efficiencies of a SPUI interchange with excellent compatibility with future expansion for an estimated $39 million.

Design details

The highway will still shift to the west and pass under I-90. Ramps will meet at a single point just north of the interstate. Eastbound ramps will pass underneath the interstate to connect with the highway. The westbound off-ramp will be elongated and will not curve.

Because the interchange will be shifted north, there will be fewer impacts to the local system. The signal currently controlling the Ross Point Road, Seltice Way, ID-41 and I-90 intersection will be removed and replaced with a stop sign at Ross Point Road. After being shifted, the highway will connect with Seltice Way at Herborn Place and be controlled with a signal.

After construction, the Centennial Trail will likely pass underneath the interstate and continue north. A connection to the neighborhood south of Seltice Way will be constructed.

View offset SPUI design

Seltice to Mullan

In spring 2019, the limits of this project were expanded to include the ID-41 and Mullan Avenue intersection–which was set to be improved within a few years after the interchange redesign–to ease construction impacts and to bring benefits to the public sooner.

Although this portion has yet to be designed, changes to the ID-41 and Mullan Avenue intersection are expected, as well as some type of curbed median to limit left turns onto the highway between the interchange and Mullan Avenue. Limiting left turns eases congestion and improves safety.

January 2019

Preferred design selected

After receiving public feedback and continued discussions with the city of Post Falls, ITD has selected a new design to improve safety and capacity at the interchange. Called an offset SPUI, the latest design eliminates the loop ramp, reduces impacts to Seltice Way and achieves the efficiencies of a single-point urban interchange at a lower cost.

ITD will continue to develop details for the final design and construction.

Preferred design selected

Winter 2018/2019

Selecting an alternative

ITD is continuing coordination with local jurisdictions, and after evaluating public comments submitted after the open house, will select an alternative--whether it be the single-point urban interchange or the half-diamond interchange--to pursue. The decision will likely be made before 2019.

Fall 2018

Value Planning

ITD met with the city, planners and engineering firms to assess the needs of the project before creatively and collaboratively identifying solutions. Nine alternatives were explored by the group, and the department has selected two alternatives to present to the public at the meeting in early November.

Spring 2018

Early design

Engineers began collecting data to assess the needs of the project, ranging from traffic volumes to stakeholder identification, to develop various interchange designs.