Règles de la route

Before changing lanes, you should:

Panneau routier de Colombie-Britannique — Signal first, check mirrors and blind spot, then move smoothly when clear
Afficher la réponse et l'explication
Bonne réponse : B. Signal first, check mirrors and blind spot, then move smoothly when clear

Signal → check (mirrors and shoulder) → move. Signalling after the move gives no advance warning. The blind-spot check is the safety step that mirrors cannot replace.