Drivers heading to or from Montreal this weekend will face substantial challenges using several routes.

The Lafontaine Tunnel will be subject to extensive closures from midnight Friday until 5 a.m. Monday.

All southbound lanes on Highway 25 will be closed between Sherbrooke St. and the Tellier/Futailles entrance overnight Friday, Saturday, and Sunday.

Two lanes will be open to southbound drivers from 7:30 a.m. until midnight Saturday, and from 8 a.m. Sunday until midnight.

Drivers coming into Montreal will be only one lane available between 10 p.m. Friday and 7:30 a.m. Saturday, and again from 10 p.m. Sunday until 5 a.m. Monday.

Two northbound lanes will be open during the day on Saturday and Sunday.

Turcot Interchange

The approach to downtown via Highway 20 and the Decarie Expressway is off limits as of midnight Friday July 14.

The ramp from Highway 15 south to Route 136/Highway 720 east will close at that time and reopen at 5 a.m. Monday.

The ramp from Highway 20 east to to Route 136 will also shut down at midnight Friday.

Transport Quebec is recommending drivers head south to the Bonaventure and enter the city via Highway 10.

Mercier Bridge

The Mercier Bridge will be closed overnight Friday, starting at 10 p.m.

Crews will be replacing bearings underneath the bridge, which will require all lanes to be closed until 8 a.m. Saturday.

St. Pierre Interchange

Once again, the eastbound approach to Highway 20 from the Mercier Bridge will be closed this weekend, from 11 p.m. Friday until 5 a.m. Monday.

Drivers will be able to take a new, temporary exit leading onto Notre Dame St. West, St. Pierre Ave., and Richmond St.

Two eastbound lanes on Highway 20, between the entrance from route 138 to Exit 64, will be closed overnight Friday.

Meanwhile one westbound lane from Highway 20 to the Mercier Bridge will remain closed until mid-August.