CPL signals and how they operate

NW Mailing List nw-mailing-list at nwhs.org
Tue Feb 4 16:19:09 EST 2020


I have added the intermediates to my document (attached) and, as always,
have some questions about specific aspects that seem like they should have
been included for completeness, but were not.  I have constructed what I
believe they should have looked like from other aspects and included them
on a red background to indicate they are not a part of the original
documentation.

Also, I do not completely understand the distant signals mounted on their
own masts as I have only seen the notched (fishtail) arms combined with
home signals.  My supposition is that perhaps a train entering a long block
would be allowed by continue at rated speed by a home signal at the
entrance to the block showing proceed even if the next block in advance
were occupied.  Then when the train reached a stand-alone distant signal
somewhere in the middle of the block, it would indicate to the engineer to
either “Proceed Under Control, Prepared to Stop at Next Signal” if the next
block in advance were still occupied, or “Proceed” if the next block in
advance had cleared by this time.  This would have the effect of breaking
the long block into two blocks without the need for a home signal or
additional track occupancy detection equipment.  For safety, the distance
from the distant signal to the home signal for the next block in advance
would need to be long enough to allow for sufficient slowing of a train.
Once again, this is only my speculation and any additional
comments/information will be greatly appreciated.
Jim Cochran
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