On Sat, 05 Dec 2009 23:39:03 GMT, "Richard J."
wrote:

Re Paris: It's possible that the PEDs on line 14 were for both
purposes. But the PEDs now being installed at every station on line 1
have been presented to the public as being necessary for the
introduction of unmanned trains. I can't think of any other reason for
them.

They also provide a benefit (in the case of the semi-outdoor airport
shuttles) in that they mean the station platform can be indoors yet
provide direct access to the train. That said, the approach at
Watford Junction (a longish building with several sets of doors to the
platform itself) can pretty much provide that.

Neil

--
Neil Williams
Put my first name before the at to reply.