It seems there is a trend towards variable tolls around world lately.
In my beloved Australia there is talk introducing it for the Sydney highway systems including the Sydney Harbour Bridge. And in Illinois they are also proposing the same thing (not to any harbour bridge though).
In Japan, the tolls for freeways are super high. But that hasn’t stopped people from using them. As Hugh Bartling has pointed out it only serves to stratify people – the rich-and-the-willing-to-pay type and the poor-and-cannot-afford-it type. And Japan seems to be like this.
How the revenue is spent is an important issue. If it is not used to create new alternative forms of ecologically sound mobility it is pointless and it ends up being a “revenue grab” as David Jeffery calls it.
As I have said before, money makes it all too easy to redistribute for other (mis)uses. Money, like labour, should remain closely related to the point it is collected. Otherwise we lose sight of the reasons for collecting it in the first place.