Here is an interesting video that explains why separated bike lanes are much better than the bike lanes that are painted on the roads.
"A true bicycle lane is one that can be used by a child".
While the video describes the effectiveness of seperated bike paths compared to bike lanes in New York, it is equally applicable to Melbourne.
The new separated bike paths in Swanston Street Carlton are an excellent example of how well these work. You don't have to worry about motorists parking across the bike path or entering it quickly. The bike paths start heading north of the city just past the City Baths. Give them a try.