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Re: From LA Times: Witnesses say light was green just before Metrolink train crashed
Author: Joe
Date: 10-06-2008 - 12:51
SignalMaintainer Wrote:
-------------------------------------------------------
> What type of signal was the one in question? If
> it was an original (SP) Union Switch & Signal
> there is a color filter which is presented (pulled
> in) before the bulb by a relay, instead of the
> replacement 3-lens systems. The "default"
> indication (no active pull-in for either green or
> yellw) is the red BUT if the green aspect "hung
> up", it may well have stayed there regardless of
> what the correct aspect should have been. The UP
> has replaced a majority of these with new 3-signal
> systems but there are a lot of the older signals
> online.
>
> IF THE SINGLE LENS/COLOR FILTER SIGNAL IS THE ONE
> USED IN THIS CASE, THERE IS A POSSIBLE - HOWEVER
> SLIM THE ODDS - CONDITION THAT THE SIGNAL SYSTEM
> HAD "HUNG UP" IN THE MOVEMENT AND A GREEN
> INDICATION WAS ERRONEOUSLY DISPLAYED. And trying
> to "play back" the signal aspect would be
> impossible as the mechanics of this system are too
> inter-dependent and impacted by temperature,
> humidity, wear, dirt, contact, etc...
>
> This could be a real eye-opener.
Most of the signals in that area have round targets with the three individual aspects in an "upside-down triangle" pattern. Not sure of the manufacturer... The US&S "searchlight" signals were replaced when CTC was installed in the early '90s...
-------------------------------------------------------
> What type of signal was the one in question? If
> it was an original (SP) Union Switch & Signal
> there is a color filter which is presented (pulled
> in) before the bulb by a relay, instead of the
> replacement 3-lens systems. The "default"
> indication (no active pull-in for either green or
> yellw) is the red BUT if the green aspect "hung
> up", it may well have stayed there regardless of
> what the correct aspect should have been. The UP
> has replaced a majority of these with new 3-signal
> systems but there are a lot of the older signals
> online.
>
> IF THE SINGLE LENS/COLOR FILTER SIGNAL IS THE ONE
> USED IN THIS CASE, THERE IS A POSSIBLE - HOWEVER
> SLIM THE ODDS - CONDITION THAT THE SIGNAL SYSTEM
> HAD "HUNG UP" IN THE MOVEMENT AND A GREEN
> INDICATION WAS ERRONEOUSLY DISPLAYED. And trying
> to "play back" the signal aspect would be
> impossible as the mechanics of this system are too
> inter-dependent and impacted by temperature,
> humidity, wear, dirt, contact, etc...
>
> This could be a real eye-opener.
Most of the signals in that area have round targets with the three individual aspects in an "upside-down triangle" pattern. Not sure of the manufacturer... The US&S "searchlight" signals were replaced when CTC was installed in the early '90s...
