Permeability

http://en.wikipedia.org/wiki/Permeability_(spatial_and_transport_planning)

Loosely speaking, permeability is the idea of keeping our streets and paths open. It is generally discussed in my world with reference to cycling (and walking to some extent) . Even if we do limit the access of motor vehicles with one way streets, block offs and no entries, cycling should not be similarly restricted. It takes much campaigning to get unecessary restrictions on cycling undone, and ion the rare occasions it is done, it's hailed as a "cycle facility". The same thing happens if plans to restrict cycling are corrected before anything is built; I successfully campaigned to stop cycles from being banned from turning left into Crow Lane from Whalebone Lane. Welcome though the exemption was, cycling hasn't gained anything -it's had to figh to keep what it had.