A second set of bridge replacements will close Highway 417 in both directions on Saturday and Sunday, a week after the bridge over Kirkwood Avenue was replaced.
The bridges over Carling Avenue are 55 years old and weigh 600 tonnes. It will take less than 24 hours to replace them, according to the province.
More than 100 workers using state-of-the-art technology will replace the bridges overnight.
All lanes of the highway will be closed between the Parkdale and Maitland exits.
Carling Avenue westbound will also be closed between Merivale and the 417.
The rapid bridge replacement technology has been used to replace Highway 417 bridges at Island Park Drive in 2007, Clyde Avenue in 2008, Carling Avenue eastbound in 2011, and last week at Kirkwood Avenue.
People can watch the construction work live from bleachers that will be set up at Food Basics on Carling Avenue.
Construction will begin at about 6 p.m. Saturday and is scheduled to end at about 11 a.m. Sunday.