Automatic signal in double line block section

["jgnestor" <86367@one.net>]

On the up line between Medway Jct and Wingello (NSW main south) there is an
automatic signal  (112.0) with its associated distant.  This is  a double
line block section.  In addition, Wingello is frequently switched out,
allowing the block section to be Medway Jct- Bundanoon (or -Exeter if
Bundanoon is switched out).
Can anyone tell me exactly how this works?  I presume trains cannot be let
go from Medway Jct to auto 112.0 if Wingello is switched out, as this could
result in two trains being in section 112.0-Bundanoon once 112.0 had cleared
(indicating only that the line was clear to Exeter up home or so)

Come on Eddie.