Toronto's transportation services department is advising motorists to consider using alternate routes while the machines, each weighing 400 tonnes, are moved.
Transportation director Myles Currie says public transit should be considered first because two recommended alternates, Bathurst and Dufferin streets, will be a lot busier than usual.
The Allen from Lawrence to Eglinton avenues will close, starting at 9 p.m. The closure will grow to a stretch between Sheppard and Eglinton avenues at 11 p.m. and that will remain closed until 5 a.m. Monday.
The boring machines, named Dennis and Lea, have been digging out the western segment of the Eglinton Crosstown underground tunnel, part of the light rapid transit project.
People will be able to reach the site on foot and early birds can watch as the machines are extracted, between 2 a.m. and 5 a.m. on both Saturday and Sunday. Bleachers will be set up to accommodate the curious.
Once the machines are moved to the east side of Allen Road they will continue their tunnel drives east toward Yonge Street.
Dennis and Lea were launched at Black Creek Drive in the spring of 2013. They have been drilling eastward, creating tunnels 5.75 metres in diameter, at a rate of 10 metres a day.