I-90 Exit 406 Interchange Modification Study and Environmental Assessment

Environmental Assessment Now Available

The Environmental Assessment (EA) for this project has been signed by SDDOT and FHWA, marking the beginning of the public comment period for the project, and specifically on the EA and the Proposed Action that has been recommended. Links to the EA document and its appendices are below. Copies of the EA are also available for viewing at Brandon City Hall and the SDDOT Area Office in Sioux Falls.

Formal comments on the project and the Environmental Assessment will be accepted until Friday, October 4, 2019.


Project Overview

The South Dakota Department of Transportation (SDDOT), City of Brandon, Sioux Falls Metropolitan Planning Organization (MPO), and Federal Highway Administration (FHWA), have identified a need to revisit and further study the originally proposed alternatives and other potential improvements to the 1-90 Exit 406 interchange. The study includes an Interchange Modification Justification Report (IMJR) and associated environmental investigation.

Study Overview



Steve Gramm
SDDOT Project Manager

Ben White
Consultant Project Manager


Send Us Your Comments

Public Comment Summaries


Public Information Meeting #3

As part of the comment period, the project team hosted a public meeting on the evening of Wednesday, September 18th in Brandon. Details about the meeting, including the formal public advertisement are as follows:

Environmental Assessment Documents


Public Information Meeting #2

Build Alternative Figures

The following alternatives were carried forward for further evaluation in the development of a proposed action for this project.


Public Information Meeting #1