Just came across a heavily street-wise book on the typology of bollards, posts and such: those meaningful obstacles which ensure flatland is used one way, not another. Author Helmut Höge presents his remarkable collection and observations which offer a striking new angle to the politics of space. A must read for retired leapfrog enthusiasts and post-most urbanists alike.
The catalog title above claims something like “The attractive solution for city confines”. As Höge points out, it remains dubious whether subversive creatives were anticipating a sport like parkour or if blatant phallus imagery is all there is to it.