Cab Signal Questions/ATS/ATC

[Anonymous]

Dear everyone,
Hello. The recent thread "smoke signals" drove home to me how little I know about cab signals. I understand how the system works for displaying an aspect in the cab, but was hoping some of you could expound on some areas for me:

1.) What is the difference between ATS and ATC, and is it any different than "straight up" cab signals. Are there any other types of cab signalling systems?

2.) What aspects can be displayed in the cab?

3.) What is the proper course in acknowledging the signal? Which lever would you press?

4.) What is the "seal" for?

5.) What voltage do the systems run on?

6.) What makes cab signalling superior to lineside signalling?

7.) If cab signalling is superior, then why still have lineside signals?

8.) If the cab signals fail on a lineside signalled territory, the train can still proceed at 40 mph. At the same time, I believe a train can proceed in lineside signal only territory at up to 79 mph. Why would a train then be limited to 40 mph, when otherwise it could run at 79 in non cab-signal territory.

I realize that I'm asking a lot of questions here. If you just wanted to give me the "basic explanation," that would be fine as well. I appreciate all of your help.

Sincerely and gratefully,
Daniel Parks

[Gluefinger]

Originally posted by trainjunky29




2.) What aspects can be displayed in the cab?

Depends on the system, but most are simplified from the actual signals. Most cab signal setups either have 4 or 9 possible signals shown.

6.) What makes cab signalling superior to lineside signalling?

Weather and other various obstructions can obscure the view of a signal from a crew. It's much easier to look on top of the control stand than to squint for a signal during a blizzard.

7.) If cab signalling is superior, then why still have lineside signals?

Cab signaling is expensive to install, and in terms of ATS and ATC, every engine leading on the line must have the correct system. That means if an engine is to be able to interchange, it should have all of the possible types of cab signals to be able to lead.

8.) If the cab signals fail on a lineside signalled territory, the train can still proceed at 40 mph. At the same time, I believe a train can proceed in lineside signal only territory at up to 79 mph. Why would a train then be limited to 40 mph, when otherwise it could run at 79 in non cab-signal territory.

I'm not sure on this one, but I'd guess that a problem with cab signals could indicate a problem with the entire signal system as well, meaning there should be some caution in watching the wayside signals, and the 40 mph speed limit would help to reduce potential accidents.

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