Challenge

In north Lewiston, Idaho, US 12 and State Highway 128, is a critical intersection that serves local businesses, vital freight routes, and access to the Port of Lewiston and Port of Wilma. The Idaho Transportation Department (ITD) was looking to address operational inefficiencies and safety concerns at this intersection, including high traffic volumes, spacing between the southern river and northern system interchange, significant crash rates, and inadequate connectivity. These challenges are all compounded by the projected traffic growth through 2050.

Solution

Our team evaluated and proposed multiple intersection improvement alternatives, including roundabouts, signalized intersections, alternative intersection and rerouting options, using a tiered analysis approach. ITD selected the alternatives that were likely to be most feasible and effective for further consideration and eventual implementation.