7j43k"...a signal", as opposed to the plural, implies to me stub-ended station trackage.
guess i'm using wrong terminology. by station siding, I should have said passing siding on a single track mainline, turnouts at both ends.
and i'm concerned about control of a signal protecting the siding from one direction. of course there should be multiple signals at either end of the siding and in both directions, both entering and exiting the siding.
i'm also unsure of how siding turnouts are controlled at either end of a passing siding. With ABS, does a turnout position, regardless of whether it is manally switched or not, affect an ABS signal?
greg - Philadelphia & Reading / Reading
Could it be designated "within Yard Limits" ?
http://www.pcrnmra.org/conv2012/handouts/allAboutYardLimits.pdf
93. Movement within Yard Limits
Yard limits are designated by Timetable and indicated by yard limit signs.
Within yard limits, movements may be made on a main track by verbal permission of the Dispatcher (or Operator when authorized by the Dispatcher).
The leading end of movement within yard limits must operate at Restricted Speed, with the following exceptions:
Within yard limits, movements against the current of traffic must not be made without permission of the Dispatcher, who must first ensure that no opposing movements have been authorized.
Regards, Ed
gregc sorry to revive this, but am working on implementation for a station siding (not run-around). There's a signal on the main indicating whether it is safe to proceed into the siding. But the siding has two tracks. i believe one way to implement this is that the signal should indicate stop if the siding turnout is in a position to route the train onto an occupied siding track and should be clear/approach if the turnout is in a position to route the train onto an un-occupied track. if true, the signaling system depends on turnout position is this correct?
sorry to revive this, but am working on implementation
for a station siding (not run-around). There's a signal on the main indicating whether it is safe to proceed into the siding. But the siding has two tracks.
i believe one way to implement this is that the signal should indicate stop if the siding turnout is in a position to route the train onto an occupied siding track and should be clear/approach if the turnout is in a position to route the train onto an un-occupied track.
if true, the signaling system depends on turnout position
is this correct?
"...a signal", as opposed to the plural, implies to me stub-ended station trackage. As such, you don't need any signalling at all, because the trains are in yard limits, and cannot go faster than they can see and stop. For the trackage preceding the yard, they are expected to slow down enough so that they will comply with speed restrictions when they enter the yard.
Ed
I'm not sure if CTC would be the only situation the signals would indicate that, but yes there are situations where train orders / timetable etc. would be used. I thought about going into that, but the OP's question was about signalling a run-around track at the end of the line. I was explaining it wouldn't be signalled, with an example of a situation with a somewhat-similar track arrangement that would need signalling.
wjstix Generally a run-around track like you're describing (in the OP) is only used at the end of a branch line, where there's only one train running at a time. There really wouldn't be a need for signals of any kind in that situation. I lived for many years on a branch line that ended in a run-around track, and it didn't have any signals. Signals would be needed where you had a busy single-track mainline with side-tracks or stretches of double-track where trains could pass each other. As the trains approached each other, the signals would indicate which train stayed on the mainline and which went into the siding so the other could pass.
Generally a run-around track like you're describing (in the OP) is only used at the end of a branch line, where there's only one train running at a time. There really wouldn't be a need for signals of any kind in that situation. I lived for many years on a branch line that ended in a run-around track, and it didn't have any signals.
Signals would be needed where you had a busy single-track mainline with side-tracks or stretches of double-track where trains could pass each other. As the trains approached each other, the signals would indicate which train stayed on the mainline and which went into the siding so the other could pass.
Only if a form of CTC is in effect do they indicate which train uses the main track or siding. Modelers I think seem to think that all signalled track is CTC or it's equivalent. There were many fairly busy single track main tracks that only had ABS, where train orders dictated who held the main/took siding.
Even today there are main tracks with ABS where a track warrant or it's equivalent, dictates which train holds or clears the main track. We have one segment where the ends of the sidings have dispatcher controlled switches and signals, but it's not CTC. It's in track warrant territory and the controlled switches/signals are considered to be manual interlockings. To occupy the main track between the interlockings, track warrant authority is needed.
Jeff
7j43kIf the siding is to be detected and signaled also, then you would place 3 signals at each of the two track switches. A total of 6 signals. The signals at "the pointy end" of the switch will have two heads, one above the other. The signals facing the other way will be single head.
This applies whether the siding is bonded or not. The difference is that if the siding is not bonded then the best signal you can get into the siding is a "lunar", low or restricting, indication that tells the train to proceed at restricted speed into the siding. Pretty much any time you have a signal into unbonded, non-signalled track (such as into a yard) the best signal you can get is a lunar or restricting.
Dave H. Painted side goes up. My website : wnbranch.com
Never mind.
Larry
Conductor.
Summerset Ry.
"Stay Alert, Don't get hurt Safety First!"
Dave and Ed
thanks.
both responses very informative and helpful.
I'm restating a lot of what Dave has said. And I do hope he will correct my errors.
If you want signals, there are two ways to go:
If the siding is NOT signaled/detected, but the mainline is, then you can view the siding as being in the "middle" of a block--an element of trackage in that block. Then you'll have signals facing each direction out at the block boundaries. Only the mainline is detected. Here's what you'll see out at the block boundary:
Thus, when a train, or any part of the train, is on the mainline, the block's signals will show red. BUT ALSO: Whenever any switch on the mainline is thrown to diverging, it will also trigger red block signals.
If the entire train is placed in the siding AND all switches are thrown to straight through, the block signals will show green and another train may pass through the block.
So, the signals you install will be the regular pair of signals out at the block boundary, wherever that happens to be. It might be just beyond the siding switches. Or it might be a long ways out. Your choice. And there might be more track switches on the signaled mainline than just the two siding switches. When ANY of those switches are set to diverge, they should drop the appropriate signals to red.
If the siding is to be detected and signaled also, then you would place 3 signals at each of the two track switches. A total of 6 signals. The signals at "the pointy end" of the switch will have two heads, one above the other. The signals facing the other way will be single head.
When you leave this assembly of two switches and 6 signals, going down the track for aways, the next signals you will see will be the regular signal pair at a block boundary.
And, also, any track switches in any of these blocks that can be thrown to a diverging route will also drop the appropriated signals to red.
I think that pretty much lays out your signal placement options. And a little bit about how they will act.
gregcmy basic understanding of signaling is to position signals at either end of a siding used to allow trains to pass one another on a single track mainline.
Not necessarily.
Nothing requires signals at a siding or, especially, a runaround. The arrangement of signals depends on the signal system being used. In a TT&TO/ABS, TWC/ABS, DTC/ABS ssytem there will not be signals at the switch, there will be signals in both directions beyond the switches on either end. In CTC there will be three masts or heads at each controlled switch.
MR doesn't host photos and I haven't found a hosting service since Photobucket started charging, so I can't post a diagram.
The key thing is what signal system do you have? ABS or CTC? Are the switches controlled by a dispatcher or control operator or a interlocking operator, or just the crew?
You don't need signals, the runaround can be in a block and the switches hand thrown. That means it really won't be a passing siding and won't be listed on the timetable page as a passing siding, its just a station. The train can use the runaround at will, BUT before the train departs in the opposite direction, it would have to get permission from the dispatcher to move in the new direction.
Assume CTC. The control points are not at the switches but are beyond the runaround, the runaround is in the middle of a block. The eastward train drives into the block under signal indication. It gets track and time in the block. It finishes its switching and runs around the train to return, becoming a westward train. It calls the dispatcher, releases it track and time an asks permission to depart in a westward direction. The dispatcher grants permission and it runs to the first signal and is governed by signal indication from there.
not sure about terminology
my basic understanding of signaling is to position signals at either end of a siding used to allow trains to pass one another on a single track mainline.
my small pt-to-pt layout has two station sidings. Each siding is intended to allow the engine to change positions so the train can reverse direction as well as switch cars on team track and nearby spurs. But if there is a signal at each end of the siding, this doesn't seem allowed if the blocks at either end of the siding are occupied (not clear).
it seems that there are sidings intended to allow trains to pass one another and there are sidings or run-arounds intended to support switching operations.
i hope someone understands my questions and can help clarify my understanding