Since SMRT is electronics oriented, all they got to do is to
wait for codes and follow the signal lights.
In the real railway application, flags are widely used.
In this case, the flags are placed there to remind drivers (TO
in this case) that the section after that is a no-entry zone. In
layman terms, they cannot go over due to works or derailments or
rail fractures or anything that prohibits train movements.
Pasir Ris and Joo Koon are terminus. So, it's of no use to put
the flags there. Even if they proceed on further, there is a yellow
buffer stop that will prevent the train from proceeding. If the
train proceeds, the buffer will stop the train, and causing it to
derail and suffer minimum impact (if the train is slow)
As Jurong East has no buffer stops, flags are used to warn the
drivers about it.
Indeed.
Just to add on.
In Japanese systems these are called 'Temporary Signal Machines'
(臨時信号機) in which its not a machine, but just
a board or flag in this case to denote temporary speed limitations
(yellow triangle with speed limit below it), denote clearance from
temporary speed limit (a green circle with white border) and other
scenarios that do not require a regular signaling machine.
For station staff flags, the most commonly used are green
and red, one to proceed and one to stop. Staff at Jurong East and
other stations use yellow, one color to denote clearance in caution
(for Japan side, whether SMRT is the same depends) as well.
Another method is to use handheld lights to swing or flash to
denote different signals for use in door clearance.
