Project Background, Understanding, and Need for Study

Because of numerous bridge strikes, the South Dakota Department of Transportation (SDDOT) has determined that the I-90 Exit 387 (Hartford) interchange will need to have a new overpass structure in the near future.  The SDDOT in conjunction with the City of Hartford, Minnehaha County, the Sioux Falls Metropolitan Planning Organization (MPO) and the Federal Highway Administration (FHWA) has concluded that a study is needed to determine what size of structure will be needed to handle current and future traffic levels.

At present, the SDDOT intends to let for construction a project to reconstruct the Exit 387 interchange and portions of the Minnehaha County 151 / Western Avenue crossroad.  The exact limits of construction will be determined as part of the study.  This construction project is currently planned for Federal fiscal year 2025, for which this study will help bring to fruition.

Study expectations and objectives, identified in the study Request for Proposal (RFP), include:

1. Interchange Modification Study: The development of the Interchange Modification Justification Report (IMJR) for the interchange.
2. Environmental Study: The development of all environmental documentation necessary for the construction project to modify the interchange and related crossroad improvements.
3. Topographic Survey: Conducting the survey data necessary for design.

Study Area

The I-90 Exit 387 (Hartford) Interchange Study area includes (corridors highlighted in red in Figure 1):

• Minnehaha County 151 / 463rd Avenue /Western Avenue: from the intersection with 261st Street to the intersection with 260th Street / Mickelson Avenue, approximately 1.0 mile (referred to as Western Avenue)
• SD38: from the I-90 Westbound Ramp Terminal to the I-90 Eastbound Ramp Terminal, approximately 0.3 miles,  
• I-90 Mainline: from MRM 384± west of the I-90 Exit 387 interchange to MRM 391± east of the I-90 Exit 390 interchange, approximately 7.0 miles,
• The ramps for the I-90 Exit 387(Hartford) interchange, and
• The ramps for the I-90 Exit 390 (SD38/Buffalo Ridge) interchange
• The study area may expand depending on potential detour routes for analysis identified during the study.

Study intersections within the study area are as follows:

1. Western Avenue - 261st Street
2. Western Avenue - Jeffery Street
3. Western Avenue - EB Ramp Terminal
4. Western Avenue - WB Ramp Terminal
5. Western Avenue - Diamond Trail
6. Western Avenue - Opal Lane
7. Western Avenue - Mickelson Road
8. SD38 - EB Ramp Terminal
9. SD38 - WB Ramp Terminal