U.S. 95, Thorncreek Road to Moscow Project


The design process consists of selecting a preferred alternative in conjunction with the environmental process, the evaluation of design standards, and the preparation of a plans, specifications, and cost estimate (PS&E) package in conformance with these standards. The design process is outlined below.

The concept phase will begin at the same time as the environmental phase begins. The goal during the concept phase is to establish the purpose and need for the project, as well as design standards. Furthermore, possible alignment alternatives are evaluated and ranked based on environmental impacts, functional considerations and costs.

Once the concept is approved, the preliminary design phase begins. This phase consists of studies and information gathering that will be required for further environmental studies and final design. Such studies include geotechnical reports, hydrology/hydraulics studies and the evaluation of structural requirements (for bridges, box culverts and other structures).

Final design consists of preparing detailed plans for the proposed roadway and any proposed structures.

These plans, along with specifications (contract documents) and a construction cost estimate are then prepared for bidding purposes. The PS&E package preparation cannot begin until the environmental and right-of-way approvals have been obtained.

Fall 2018 Update

The Idaho Transportation Department is continuing to work on final design plans and right-of-way appraisals for the U.S. 95, Thorncreek Road to Moscow Project. ITD anticipates this work will be completed this spring.

The Federal Highway Administration and ITD evaluated many alternatives for the new highway alignment, including western, central and eastern routes. The final eastern route (E2) was chosen after a multi-year environmental review process. ITD received a Record of Decision (ROD) from the Federal Highway Administration in March of 2016. The ROD gave ITD the authority to begin final design and purchase land.

A legal motion was brought against FHWA and ITD regarding the Environmental Impact Statement and Record of Decision for this project. In August 2017, the U.S. District Court for Idaho ruled against the motion in favor of FHWA and ITD.

Please call Ken Helm at (208)799-5090 if you have any questions about the project.