In message , Helen Deborah Vecht
writes

At Uxbridge, I think the practice is to try and separate the Met Line
from the Piccadilly. Keeping both sets of doors open would encourage
yobs to use the trains as shortcuts between platforms and allow trains
to get very cold.

The reason platform 2 isn't used at Uxbridge is that the mirrors and
monitors are not adequate to see the length of the train properly from a
Piccadilly line train. On the side we do open (Platform 3) you can
observe the whole length of the train from the cab when departing. I
assume (but don't definitely know) that similar problems occur with the
Met. trains.

As any train can use any platform there, it would be difficult to
maintain any separation anyway.
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