严格地说,从一个左转道左转到双道上,根据安省驾驶规则来说应该转到左道,然后再换道到右边。
Diagram 2-27: Two-way road to a two-way road.
Turn from the lane closest to the centre line to the lane right of the centre line, following a smooth arc. Then, when you can, move into the right curb lane.
http://www.mto.gov.on.ca/english/dandv/driver/handbook/section2.6.4.shtml
但是,美国的密苏里(可能其他州也是)就是驾驶员自己选,但是要保证右道是free of traffic.
ONE-WAY STREET ONTO A TWO-WAY STREET
Begin the turn in the left lane. Enter the two-way road to the right of its yellow dividing line. If the two-way road is a four lane road, you may enter it in the right lane if that lane is free of traffic.
TWO-WAY STREET ONTO A TWO-WAY STREET
Begin the turn with your left wheels as close as possible to the yellow dividing line. Enter the road to the right of its center line. If the road onto which you are turning is a four-lane road, you may enter it in the right lane if the right lane is free of traffic.
http://dor.mo.gov/forms/Driver_Guide_Chapter4.pdf
所以,理论上讲正确的驾驶就是一道左转到多道时要转到左边道。