On Sat, 3 Jan 2004 09:47:35 -0000, "Paul Oter"
wrote:


"Aidan Stanger" wrote in message

The big mystery is why so few crossings in London are marked like that.
Space is such a constraint that most of London's signalled crossings use
the Barnes Dance sequence UIVMM.

I suspect the main constraint is that a diagonal crossing, being a greater
distance, requires vehicle traffic to be stopped for longer than with an
ordinary orthogonal crossing. So it's pedestrian convenience vs motorist
convenience.

PaulO

An optimal phasing for a number of pedestrians would surely depend on
where pedestrians are trying to get to, and the relative numbers
wanting to make a simple orthogonal move and those wanting a diagonal
move?

If all pedestrians wanted to end up on a diagonally opposite corner,
then one diagonal move as opposed to two orthogonal moves would result
in a shorter overall crossing time and obviously a shorter stopping
time for motorists. It becomes more complex when a group of
pedestrians want to undertake both types of crossing. Clearly there's
a break even point somewhere which minimises the sum total of all
pedestrian crossing movement times.

The Japanese have a good example in central Tokyo which combines IIRC
both types of crossing, and they know a thing or two about moving
people around.

OTOH, since it seems our local authorities are anti-car to a
ridiculous extent, this is probably an academic discussion. :-)

Rgds,