Gwinnett County commissioners agreed to spend $4 million to buy right-of-way for a new interchange on I-85 in the county.

The county will also manage the preliminary engineering for the interchange at I-85 and McGinnis Ferry Road. An agreement with the Georgia Department of Transportation on the project’s framework was approved Tuesday.

The money will come from a penny sales tax in the county, and the project is intended it ease congestion.

GDOT will contribute $13.3 million, including $10.6 million in federal dollars, and will manage the project’s construction.