Are used to drivers position the vehicle in the propper lane for turnnig or going straight

for moving straight - it is needed to have the reference points.

for turning right or left- Generally the extreme left or extreme right is taken as the key lane for turning.

Explanation:

for moving straight - it is needed to have the reference points. reference point can be considered as a point which can be at middle of the divider line on the  both side of road. driver need to follow the reference point for straight drive

for turning right or left- Generally the extreme left or extreme right is taken as the key lane for turning. one should follow these lane for turning otherwise  go for straight.

france

hope this !

answer; i believe that the correct answer is (scientific approach)