Is the usage of the idiom "Move Over" in this passage clear on what side to move over to?

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?

In the passage you cited, there is no indication whatsoever as to which -direction- to move over.

There is no real semantic difference between 'if' and 'for' here (other than 'for' is not grammatical in place of the 'if').

I would presume that such a manual would have general rules like 'Carry out further rules in the safest manner possible', and 'safest' would involve some judgement and common sense (yes, the rule book is sort of a list of common sense things). For example, a general rule might be 'Do not pass on the right' but an unstated common sense exception would be 'unless you're passing a stopped vehicle in the left most lane'. For the instance you're thinking of, maybe if you're in a multi-lane traffic, the default is to move over/pull over to the right, but if you're closer to the left side you might be expected to pullover to the left. This is pure speculation, and I have no idea of the particulars of your situation.

When reading the passage, I assumed it referred to travel on a multi-lane highway where the shoulder would usually refer to the far right hand side of the road (the far left being considered the median). Given this, I assumed that it meant move over to the left, away from the shoulder where emergency vehicles (particularly police cars issuing tickets to speeders) are usually parked.

In looking at the actual Georgia law, by the way, I noticed that it does not even use the phrase move over—or the word shoulder for that matter. Instead it says make a lane change and seems to be written to allow for a lane change in either direction as long as it is to a lane not adjacent to the parked emergency vehicle.

As others have said, grammatically the sentence does not specify which way to move.

Can it be understood by any reader? At least one person was confused so clearly the answer is 'no' :) But I think the context would make it clear to "most" readers. Even if you didn't understand that it was a safety law, what sense is there in telling people to crowd over toward a stopped emergency vehicle on the side of the road?