I've been using Bob Bucklew's 3-part tutorial as my way of leaning PanelPro, and in his example, he used holding signals at Interlocks on his Quaker State layout., as I'm still learning about signals from various resources.
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Doug Wagner
Bakersfield, California
In a message dated 09/01/24 15:58:26 Pacific Daylight Time, jawhugrps@... writes:
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On 9/1/2024 5:17 PM, Doug Wagner via groups.io wrote: > My question concerns intermediate signals. Is it necessary to have an intermediate signal held from the block being occupied when it is already set up to go red when the block becomes occupied?
It is my interpretation that setting an "intermediate" signal to "held" is really "not a thing" in JMRI signaling.
That is because a "prototype" intermedate signal shows a signal's most-restrictive aspect as "Stop and proceed".? This is important! Mmaking that intermediate signal as "held" _cannot HOLD_ a train "stopped";? the signaling rules _require_ the train to come to a complete stop _before reaching the signal_, and then _allow the train to accelerate to "restricted" speed_, until there is a reason to stop, or until the train reaches a "more-permissive" signal indication.
If the dispatcher _needs_ to "hold" a train at a particular signal, and not pass that signal until the signal becomes less-restrictive, then the signal designer will implement an "Absolute" signal, not a "Permissive" one.? A North AmericaClass I railroad signal designer I know calls this type of Absolute signal a "holding signal".
The "Holding signal" does _not_ need to protect any signal.? One example I am aware of is just outside of Hinton, WV's "Avis Yard" on the C&O railroad.? "MX" interlocking is at the East end of Avis Yard.? The holding signal is on "Main 2", governing the Eastbound movement of Main 2, and is positioned _on the same Signal Bridge_ that holds signals which governs the _Westbound_ moves from Main 1 and Main 2 to enter the MX Interlocking.
The MX interlocking signal allows a coal train to leave Avis Yard but to stop at the "Holding signal" at the "departure-end" of MX Interlocking. The "helpers" can be tied-on to the tail-end of the train, without allowing the train to depart the MX Interlocking until the dispatcher gets informed that the air test is "good".? Once the dispatcher hears of the "passed" air test, he can clear the "holding signal" via the CTC control.
(The attached image shows how MX and the "Holding signal" are arranged on the CTC office machine on a friend's model.? "Signal 230" is the "Holding signal", and can be found at the redish arrow in the image. It, effectively, "controls" the departure, onto "Main 2", of a train that has already entered "MX Interlocking".)
So, you "just need" to implement an "Absolute" signal under CTC control. ? That "holding" signal does not need to be at a switch.
Can JMRI deal with this "holding signal" at the "departure-end" of a switch, as well as JMRI can "hold" an absolute signal at the "entry-end" of a switcha switch?? I don't know, because I generally do not use the JMRI signal "held" feature to enable CTC functionality.? Others who work with JMRI's signaling in more "traditional" ways can weigh-in.
> I'm going to set it up for the dispatcher to be able to set the intermediate signal to hold, but does it need to be held when the block is being occupied, such as on a OS?
In my opinion, "Yes", if you want to "prevent a train from passing a given signal under dispatcher control".? But you _cannot_ use an "Intermediate" signal to do so.
Doug Wagner