Re: New on Jan 4 NTSB update re: Amtrak 501-Not Much New?
Author: Dr Zarkoff
Date: 01-09-2018 - 22:53
> Searchlight signals are not allowed with PTC anyway.
Never heard this before. The demise of searchlight signals in favor of colorlight signals is more a case of eliminating redundant relays from the signal system, the relays being the searchlight mechanisms, and using the relays which control the mechanisms to control colorlights directly. Like all relays, the searchlight mechanisms are subject to periodic testing and have the added dager of the maintainer slipping and falling off the mast. Installing PTC also involves changing signal locations to something a lot furter apart, in order to reduce the number of signals to buy, install, and maintain.