I-29 - Exit 71 InterchangeINTERCHANGE MODIFICATION STUDY

INCREASING TRAFFIC IN SIOUX FALLS METROPOLITAN AREA

Due to anticipated growth and increasing traffic volumes in the southern Sioux Falls metropolitan area, the SDDOT plans to reconstruct the existing I-29 Exit 71 interchange as part of an anticipated 2028 construction project. Three interchange types have been carried forward from the I-29 Exit 62 to 73 Corridor Study completed in 2018:

• Compressed diamond interchange
• Single point interchange (SPI)
• Diverging diamond interchange (DDI)

The planned 2028 project will also reconstruct I-29 mainline to a 6-lane section (3 lanes in each direction) between I-29 Exit 71 and 73. The southern limits of this 6-lane reconstruction will be determined as part of the study.

The study is a collaborative effort between the South Dakota Department of Transportation (SDDOT), Federal Highway Administration (FHWA), Sioux Falls Metropolitan Planning Organization (MPO), Lincoln County, City of Tea, and City of Harrisburg.

TIMELINE TO CONSTRUCTION

The first step of the process towards construction is the interchange and environmental study, culminating with an Interchange Modification Justification Report (IMJR) and environmental document for SDDOT to submit to FHWA. Following concurrence of the proposed modifications by FHWA, the project will move into design.

• Interchange Study: through end of 2021
• Environmental Study (*NEPA): up to October 2022
• Design: 2023 - 2028

*National Environmental Policy Act (NEPA) of 1969
NEPA and Project Development Overview