The Lafontaine tunnel, which turned 50 years old March 11, will be undergoing a $1-billion facelift in the next few years.
Work on the tunnel is expected to begin in 2019 after the new Champlain bridge is completed.
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The tunnel is the longest underwater tunnel in Canada and on average 120,000 vehicles drive through it daily.
“Due to the extent of the project, there will be a major impact [on traffic],” said Transports Quebec spokesperson Laurent Lessard.
“Measures to mitigate [traffic] are already being planned for.”
Renovations to the tunnel are expected to take four years.