There is one more weekend of work necessary on the Turcot Interchange before its new configuration comes into effect.
Once it's done the new spaghetti-like loop of ground-level transfers will be in place and several highway entrances and exits will be closed for years to come.
Access to Highway 20 West will also change near the Angrignon entrance.
The consortium building the Turcot Interchange, KPH Turcot, said the next two years will be the most disruptive for drivers.
"This is the biggest phase of the Turcot project," said Sylvie Gervais.
"I would say the biggest because it impacts all the ramps, all the highways, so it will change the habits of users."
Work for weekend of Dec. 8
This weekend westbound traffic will be blocked along the Ville Marie Tunnel and Highway 20 as of midnight Friday.
The closure will start at Exit 5 for Highway 10/Bonaventure Expressway, and all westbound lanes will be closed until the Mercier Bridge.
Drivers on the southbound Decarie Expressway will only have one available route as the entrances to Highway 20 West and the Eastbound Ville Marie will be closed.
All lanes are scheduled to reopen at 5 a.m. Monday Dec. 11.
One official expected that weekend closures for sections of the Turcot would continue for months to come.
Starting Monday at 5 a.m. driving along Highway 20 and through the Turcot Interchange will be very different, as multiple entrances and exits are closed.
The Fort and Lucien L'Allier entrances to the westbound Ville Marie will be closed until 2019 because the elevated portion of the highway is being demolished.
Instead drivers will come out of the tunnel and swerve left to the lowered section of the new Route 136.
The only entrance to the westbound highway on the west side of downtown will be via Rose de Lima, which can only be accessed at St. Antoine St.
On Wednesday officials with Transport Quebec said there was a chance the closure of Highway 720 West scheduled for Monday could be delayed because of the crane mishap that happened last week.
There will still not be any access to Highway 15 South for westbound drivers -- they will have to use the Bonaventure Expressway exit that is accessible in the tunnel.
Drivers going west will find the westbound lanes of Highway 20 quite different from what they are used to. The highway through the Turcot Yards has been shifted north, closer to the escarpment, and the exit for Angrignon Blvd. will be on the righthand side.
There is also going to be a new entrance for those who head west from Ste. Anne de Bellevue Rd. and Angrignon Blvd. Those motorists will get onto Pullman Rd., then enter Highway 20 West from the lefthand side.
The decades-old entrances at Monk St. and Notre Dame St. for Highway 20 West will no longer exist.
The new configuration will also affect drivers coming from Highway 15 North and South who want to head west.
Those coming from the Decarie Expressway who want to head west will have to be in the centre lane -- which will curve to the east, as if heading downtown, before looping around and going underneath the highway.
Part of that loop will also be used by drivers coming from Highway 15 North.
Drivers coming from the South Shore and Verdun will also need to decide early on if they want to go to Highway 15 North, or to the 20.
Instead of taking a ramp in the Turcot, the decision point is near De La Vererendrye where a road parallel to the old, elevated Highway 15 North has been built.
Drivers will have to be in one lane if heading north to the Decarie Expressway, or on the new road if going to Highway 20 West.
This new configuration will be in place until 2019.