Consider this passage in the Georgia DDS 2010 Driver’s Manual: on page 40:
The Georgia Move-Over Law requires drivers to move over one lane when possible if an emergency vehicle with flashing lights is parked on the shoulder of the highway. If traffic is too heavy to move over safely, the law requires drivers to slow down below the posted speed limit AND to be prepared to stop.
Without knowing why to move over, does the "Move-Over" usage above make it clear to where?
This law is a safety law, but if someone doesn't know that, is there a grammatical support to it?
If instead of "Emergency vehicle... of the highway" it was "an Emergency vehicle is flashing its lights behind you" it might have been understood as move to the left, Therefore the only clue to the understanding of where to move to is common sense and meaning and not sentence grammar.
Note that it is phrased "Move-Over ... if an emergency vehicle ..." and not "Move-Over ... for" one
So can it be understood by any reader, that it requires to Move Over to the right and not the left?