I've never been on a engine with cab signals... I believe there's a set up lights in the cab that tells the engineman "what? ". Are there also track side signals such as in CTC ABS? territory?
If, a engineman had a yellow cab signal . he would have to know the territory as to where the controlling home signal was, Right?
Were there any advantages to having cab signals rather than straight ABS or CTC?
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Gregg posted:I've never been on a engine with cab signals... I believe there's a set up lights in the cab that tells the engineman "what? ". Are there also track side signals such as in CTC ABS? territory?
It totally depends on the design of the system. For example, the old " Automatic Train Control" system used by the C&NW RR, had no wayside signals except at interlocking plants, and only two aspects in the cab; Green and Restricting. It was/is (the UP still has to put up with it) a continuous system, and one never knew when it would "drop to restricting", at which point the Engineer is RAPIDLY applying automatic air brakes and reducing throttle, since the system forces the Engineer to reduce train speed below something like 15 MPH (maybe slower, as I can't remember the exact Max speed), all with 30 seconds!
If, a engineman had a yellow cab signal . he would have to know the territory as to where the controlling home signal was, Right?
Yes. If THAT is the design of such a system.
Were there any advantages to having cab signals rather than straight ABS or CTC?
In extremely bad weather, i.e. reduced forward visibility, real Cab Signals, like the UP, or PRR, are a real pleasure!
So, could the CNW be consider a type of PTC?
Dominic Mazoch posted:So, could the CNW be consider a type of PTC?
Absolutely NOT! There is nothing to say that, even though the Engineer is operating at under "restricting", and there is seriously reduced forward visibility, there is nothing in that antiquated system to prevent one from running into something ahead, although at only, say 15 MPH. Having fired over the former CNW system from Council Bluffs, IA to Chicago, on both 844 and 3985, that darned system will scare the crap out of the cab crew in VERY HEAVY rain/fog, when that cab device drops to restricting, then quietly goes back to clear, then drops to restricting again, all within 5 or 6 miles!
Recently TRAINS had a short article about an engineer, and his "adventures" with an automatic train stop on the ATSF near Chicago. Are/were any simulations between these systems.
Were these systems part of a federal government order for railroads to have at least a test section of automatic train stop in the, I think, the 1920's?
ATS and Cab Signals will both initiate a penalty automatic brake application within a short time, if the Engineer does not respond to their warning. That's where they are basically similar. Here's how they are different:
ATS forces the Engineer to acknowledge his awareness of either
However, ATS cannot measure the speed if the first warning is acknowledged. Therefore, if the Engineer acknowledges the ATS bell or buzzer, but does not reduce to the required speed (or stop for a signal requiring it), it does not initiate a penalty application. However, if the initial alert is ignored, a loud, "Peanut whistle" sounds inside the cab, and the Engineer must reduce speed to whatever the railroad has specified. On Santa Fe it was 40 MPH. If the Engineer waits until the whistle sounds and fails to make an immediate brake pipe reduction of at least 20 PSI*, or releases the automatic brakes and has not yet slowed to 40 MPH, a penalty application occurs and the train is stopped.
ACS (Cab Signals) require the Engineer to immediately reduce speed when the cab signal changes to a less favorable indication than the current one the train is running on. Not only does it require the Engineer to make an immediate automatic brake application but it also measures speed and the time allowed to reduce to that speed. If either does not confirm to the requirements of rules, then ACS initiates a penalty brake application and stops the train. Unlike ATS, ACS does not alert the Engineer to permanent speed restrictions, such as 30 MPH curves.
* This is a heavy application of the train brakes which would noticeably reduce speed. This can be increased to an even heavier service (non-emergency) applcation, or can be increased to an Emergency brake application if and when warranted.
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