A circular movement of the hand (during the day with a flap of bright cloth or some clearly visible object, at night with a torch or lantern).✓Bonne réponse
Hand raised above head with baton or red flag.
An arm stretched forward.
Swinging up and down with arm outstretched forward.
Explication
An emergency request for a train to stop is given by moving a clearly visible object in a circle during daylight, or a light in the same circular manner at night. Raising a baton, extending an arm, or moving an arm vertically are road-traffic gestures and do not reproduce the railway stop signal.