I've recently noticed that a lot of the plastic lit-up bollards on traffic
islands seem to be wrong - for instance, a plain white disc where there
should be a leftward arrow, or a leftward arrow where there should be two
diverging arrows, etc. Particularly bad is the route from Old Street tube
station to New North Road, where every bollard seems to be wrong. Maybe the
local kids have gone around rearranging them - it doesn't seem likely that
they could be knocked down in pairs and accidentally switched. A solution
could be to give the different styles of bollard different asymmetrical
shapes at the bottom, with matching differently shaped metal frames set into
the concrete - then it would be impossible to switch them or put them in the
right hole the wrong way around.

--
John Rowland - Spamtrapped
Transport Plans for the London Area, updated 2001
http://www.geocities.com/Athens/Acro...69/tpftla.html
A man's vehicle is a symbol of his manhood.
That's why my vehicle's the Piccadilly Line -
It's the size of a county and it comes every two and a half minutes