Major highway closures this weekend across Greater Montreal area
A-20 between Boucherville and the metro, Route 340 in Vaudreuil-Dorion, and other routes will be fully or partially closed Friday through Monday.
Sources · Quebec Nouvelles
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Update — August 18, 2026: Highway 30 will close completely in both directions over three consecutive nights beginning Thursday, August 20 at 9 p.m. through Sunday, August 22 at 5 a.m., with nightly closures varying in direction between exit 2 and Highway 40 as part of Route 340 reconstruction work in Vaudreuil-Dorion and Saint-Lazare. The Ministry of Transport and Sustainable Mobility cautions that closures could be postponed, extended, or cancelled due to bad weather or operational constraints, and directs commuters to consult Québec 511 before travelling.
Mobilité Montréal is warning drivers of major road disruptions from Friday, August 7 at 9 p.m. through Monday, August 10 at 5 a.m.
On the A-20 westbound (Jean-Lesage) in Boucherville, the road will be completely closed between Boulevard de Montarville and the next access point. Exit 95 (Boulevard de Montarville) is the detour. Congestion is expected Saturday and Sunday during daytime hours.
Boulevard de Montarville southbound in Boucherville will also be fully closed between Chemin de Touraine and the A-20 westbound access. Drivers should use Rue Ampère and Boulevard de Mortagne. A single lane remains open between Rue Ampère and Chemin de Touraine for local business access. The northbound direction stays open.
Route 340 (Boulevard de la Cité-des-Jeunes) in Vaudreuil-Dorion will operate in reverse on the westbound side between Chemin de la Petite-Rivière and the A-30 overpass. Multiple detours are available depending on final destination.
On the A-10 eastbound (Bonaventure) in Montreal's Le Sud-Ouest neighbourhood, Exit 4 (toward A-15 and A-20) closes Saturday from 10:30 p.m. to Sunday 8 a.m.; use Exit 5 (Île-des-Sœurs) instead.
The Victoria Bridge (Route 112) eastbound lane remains closed through September 10 under CN rail maintenance, operating single-file westbound traffic with timed alternation: Montreal-bound from midnight to noon, South Shore-bound from noon to midnight.
Planners should consult Mobilité Montréal's website or follow their social channels for real-time updates.
The facts
When are the major highway closures in Greater Montreal?
Major closures run from Friday, August 7 at 9 p.m. through Monday, August 10 at 5 a.m., according to Mobilité Montréal.
Which sections of the A-20 are closed?
The A-20 westbound (Jean-Lesage) in Boucherville is completely closed between Boulevard de Montarville and the next access point. Exit 95 (Boulevard de Montarville) is the detour.
How does Route 340 operate during the closures?
Route 340 (Boulevard de la Cité-des-Jeunes) in Vaudreuil-Dorion will operate in reverse on the westbound side between Chemin de la Petite-Rivière and the A-30 overpass.
When is Victoria Bridge's eastbound lane closed?
Victoria Bridge (Route 112) eastbound remains closed through September 10 due to CN rail maintenance.
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