The Sallins bypass and the Osberstown interchange will be open by the end of March.
The interchange will provide a motorway link to Millennium Park in Naas, while the bypass itself will take many of the in excess of 22,000 vehicles which pass through Sallins each day.
These two projects were being worked on in tandem with the three lane motorway widening project, which has been completed between Naas and Newbridge.
The three projects come with a combined bill of €110m.
The Sallins bypass was first mooted 13 years ago.
According to KCC today “the current environment we are all dealing with did not assist in the delivery of the scheme for the end of this year.”
The creation of a third lane on either side of the Naas - Newbridge bypass has been completed and the widened road opened over a year ago.