• Signals

  • General discussion about railroad operations, related facilities, maps, and other resources.
General discussion about railroad operations, related facilities, maps, and other resources.

Moderator: Robert Paniagua

  by Mattliverpool
I railfan at an Amtrak station in Syracuse, NY. In front of the station is a signal block. This block has seven signals. Two, Two then three. I have a few questions.

1. When a train approaches, then go on. When does these signals become active? A mile or is it closer? Soon as the train passes, they go off. How does this work, automated?
2. What does a flashing green or amber signal mean?
3. What I find odd, is when a train comes from the other way, they then come on as the train is underneath. Isn't this a safety concern? Shouldn't those signals come on before the train gets that close?

  by TB Diamond
1.) Many signal systems are set up so that a signal will light up when a train or engine enters the block in advance of the signal. This applies, if I recall correctly, in ABS territory and in CTS territory when intermediate blocks are involved. Yes, the signals will turn off after the train or engine clears the signal circuit.
2.) Did not have flashing green where I worked, but a yellow (amber) signal indicated that the speed of the train or engine should be immediately reduced to 30 mph and that the engineer should be prepared to stop before any part of the train or engine passed the next signal. In other words, expect the next signal to be red. This rule was later modified so that the red signal under certain circumstances could be passed without stopping at restricted speeed.
3.) See (1.) above. If a train was in the block in advance, the signal would be lit.

  by Railjunkie
Red over flashing yellow would be a medium approach, proceed not exceeding 30mph prepared to stop at the next signal.
Red over a flashing green would be a limited clear proceed not exceeding 45mph until entire train has passed through all interlocking switches then proceed at track speed.

  by charlie6017
Also, flashing yellow over red is "Advance Approach"-then the following would be solid yellow over red is "Approach"--meaning prepare to stop at the next signal.

  by JLJ061
Block signals are operated electrically through the track circuits, and will come on when a train is in that block, regardless of direction of travel, and will turn off again when the train leaves that block.

Most Class 1 railroads use this on/off setup mostly to extend light bulb life. Otherwise maintainers would have to be out on the road 24/7 just to replace burned out bulbs up and down the line!

  by roadster
Mattliverpool, You have selected a very busy area to watch alot of interesting train actions. As far as what each signal means print out a copy of metman499's link. These are the signals still in use in the region of CSX (former Conrail/Norac) These signals tell the engineer what action he must take to comply with rail conditions IE: clear ahead, crossing over from one track to another, stopping ahead, etc. That sheet will help you tell whats going on. FYI: the RED over flashing GREEN (limited Glear, tells me that the train is going to cross from one track to another at that CP (Control Point), max. speed 45mph. RED over Flashing Yellow (Medium Approach) train is crossing over max. speed 30 mph and needs to be prepared to stop at the next signal.