Project Overview

Since November 2005, engineering and environmental staff from the Federal Highway Administration (FHWA), the South Dakota Department of Transportation (SDDOT), Meade County, and other federal, state and local agencies have been considering various improvements to a 10-mile segment of I-90 between Exit 40 and Exit 51. The purpose is to improve interstate operations, maintain safe local access, and address future transportation demands throughout the corridor. This project will address geometric interchange and roadway design issues, including inadequate separation distances between I-90 and some segments of the service roads.

As shown below, the proposed project involves improvements to I-90, including two redesigned diamond interchanges and two relocated service roads. The four “mainline” lanes of I-90 will be realigned to allow space for eventual construction of two additional lanes, one in each direction.

Project Area Location

The proposed project is located along a 10-mile segment of I-90, which traverses the edge of the Black Hills National Forest in a northwest direction from Rapid City. The project area extends southeast from Tilford (Exit 40), which is about ten miles southeast of Sturgis to Exit 51, which is about two miles northwest of Black Hawk and seven miles from Rapid City. The Exit 51 limit matches the limit of an SDDOT project that will reconstruct the interchange at I-90 Exit 51, for which an Environmental Assessment (EA) and Finding of No Significant Impact (FONSI) was approved in February 2006 (FHWA, 2006a, 2006b). The only communities of any substantial population within or adjacent to the project area are Piedmont, located on the west side of eastbound (EB) I-90 between Exits 44 and 46, and Summerset, located near Exit 51.

* Construction schedules for the proposed improvements will be determined by availability of future funding.