Beginning Monday, drivers will not be able to turn left from Harrodsburg Road onto Mason Headley and Waller Avenue.
The medians are being reconstructed because the current configuration "is not pedestrian friendly" and is not compliant with the Americans with Disabilities Act, the city said in a news release.
The construction is expected to take about eight weeks. Work was originally scheduled to begin in July but was delayed by storms.
The city described the project as follows:
"The right turn lanes near the corner islands will be closed, routing traffic over temporary paving on the left side of the islands. The outbound right turn lane from Harrodsburg to Mason Headley will be closed and the lane width on Waller Avenue near St. Joseph Hospital will be adjusted to allow for work on curbs, accessible ramps and drainage structures.
"Once the perimeter areas are finished, traffic will be shifted back to the right side of the island. The left turn lane onto Harrodsburg Road from Mason Headley will then be closed. The other lanes will remain open."