Peter Smyth wrote:
(apologies for the earlier incomplete post)

Following the recent discussions on redrawing the zone boundaries I thought
it would be interestint to work out what the boundaries would look like on a
pure distance based system. All stations were placed into zones according to
their distance from Charing Cross. The number of stations was kept constant
so for each station that moves in, one has to move out.

In general it seems that boundaries are too close together in North and
South London and too far apart in East and West London.

(snip list)

Good stuff but I'm not sure measuring distance from Charing Cross is
fair... one of the main points of the zone system as-is is that central
London is busy and therefore Zone 1 journeys carry a "premium" cost.

Additionally, London is elongated along an east-west axis, with central
London being wider in that direction than it is along the north-south
axis (as is Greater London).

That implies that the best shape for a zone is more of an oval than a
circle.

I would say that Zone 1 should be defined by what constitutes busy
central London, and then other zones should be based on their distance
from the Zone 1 boundary.

Dave