I think that both may have a part to play.
Speaking from a position of ignorance, the biceberg solution looks like it needs significant undeground engineering. That's going to be pretty expenseive nad not always practical with communications lines, power etc etc.
I'd expect the bike tree would require significantly less capital to set up and it has the advantage of being able to be accomodated in buildings; say multi story car parks. Think shopping centres with a couple of car parks given over to a couple of bike trees, how's that for efficient use of space
I like them both.
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