354. On a two-way roadway, the driver of a road vehicle who is about to turn left at the intersection of a one-way roadway must, after signalling his intention and ascertaining that he can do so in safety, approach the centre line of the roadway on which he is driving, proceed in a straight line to the near side of the roadway he is about to enter and turn left as soon as the way is clear so as to enter the left-hand part of the other roadway.