Originally Posted by AlmostTrick
Double yellows by design have to be placed to allow safe passing of all vehicles, even large ones that are hard to see around and moving near or at the speed limit. Therefore they are painted to allow extra space in order to error on the side of safety. Like JJ pointed out in his opening post, safely passing a small slow moving vehicle like a bike is much easier and often requires less space. I also voted #2.
I don't know what double lines you are talking about. Most of the double yellows around here are as wide as two double yellow stripes with, perhaps, twice as much space between them. No extra space for erring on the side of safety. They are just slightly wider than a single broken white line - both intended to divide the roadway lanes, each with its unique passing allowed/not allowed meaning.
Caruso