Signaling question at a diamond

[lakinsa]

Here is the track set up... A single track line crosses a 2 main CTC tracks and a yard lead. The main tracks and yard lead are side-by-side. Since there is a yard lead crossing there will be a lot of stopping and reverse movements over one of the three diamonds. Rule 670 states: "Except at automatic interlockings a reverse movement within the limits of an interlocking or a forward movement after making a reverse movement must not be made without the proper interlocking signal indication or permission of the operator." Since there will be no operator here, and not to bug the dispatcher all the time, the only reasonable set up that I can see is not including the yard lead diamond in the interlocking. It would be protected by stop signs. But then the stop signs would be inside the opposing home signals for the crossing line. So when a train is routed across the mains, they would get the signal allowing them across the main tracks, but then need to stop before the yard lead and know the lead is clear before proceding. A special instruction then would be written, giving the crossing trains priority at the stop sign. Is there a prototype somewhere for this? Or is there another option that I can't think of.

Seth Lakin
Michigan City, IN

[dehusman]

If its a signalled interlocking, then you will have to include the yard lead in the circuit. And the yard lead will have to have signals on it.

The only way I can see this working is that the single track route have a manual release. A train on the single track pulls up and the crew opens the control box. If the switch lead is clear, and a light in the box indicates that the mains approaching the diamond are not occupied, the switch crew can operate a switch which starts a timer. That puts all the signals at red and waits for 8-15 minutes so that any trains that are between the approach signal and the diamond will show up. The it gives the single track train some sort of proceed signal, either a clear or a lunar. The crew closes the box and has 5 min to occupy the crossing. The double track and yard lead signals remain at stop until the train clears the crossing.

On the model you would have the single track crew stop, if the yard lead was clear they would punch a button and wait for the signal to light then pull across.

Dave H.

[Texas Zepher]

QUOTE: Originally posted by lakinsa
the only reasonable set up that I can see is not including the yard lead diamond in the interlocking. ...

Or is there another option that I can't think of.

I think I'm missing something, why is this the only reasonable set up? Isn't including the diamond in the automatic interlocking one answer to other question. Or How about using ABS interlocking for the yard lead diamond rather than CTC.

Are these representing two rival railways, or just one railroad crossing itself?

[dehusman]

It doesn't matter whether its ABS or CTC. The issue is the signal system can't be permitted to give a proceed signal while the interlocking is occupied by a train on a different route. The problem with just stop signs is if the trains on the CTC main are running on a clear signal, the single track route can't just stop , look both ways and then pull out into the crossing. Doesn't work that way.
The prototype has to provide warning to the trains on the double track main before the train on the single track main occupies the crossing. The real problem is the yard lead. A switcher could have it blocked for a long time before it clears, significantly delaying the trains on the single main. And since they operate without signals they can just pop into the crossing anytime they want.

Dave H.

[Texas Zepher]

QUOTE: Originally posted by dehusman
And since they operate without signals they can just pop into the crossing anytime they want.

Ok, that's the part I don't understand. Why is this allowed to happen? Here in Denver where a yard lead (the one to Union Station) crosses the main, there is a section of about 50' that has a little sign that says "beginning CTC control," cross two tracks, "end CTC control."

[lakinsa]

>The problem with just stop signs is if the trains on the CTC main are running on a clear signal, the single track route can't just stop , look both ways and then pull out into the crossing.

Right, And that is why I was asking the question... Could be there stop signs inside a interlocking? Trains on the single track route pull up and get the signal, but still have to stop and look both ways before crossing. That would allow the mainline trains to be protected and any yard movements stop and for conflicting (single track line) routes.

[dehusman]

If they "get the signal" why do you need stop signs? That's the point of the signals and the timing circuits. They look out way farther than the crew can see.

The trains on the yard track already have to be able to stop short of a train. They're not the issue.
By the way you never have said how the single track main is controlled or what the max speed is.

Dave H.

[dehusman]

Texas Zephyr wrote:
"Ok, that's the part I don't understand. Why is this allowed to happen? Here in Denver where a yard lead (the one to Union Station) crosses the main, there is a section of about 50' that has a little sign that says "beginning CTC control," cross two tracks, "end CTC control."

Remember I am talking about the yard lead, NOT the 2 CTC main lines. Nothing has been said about how trains operate on the single track, we don't know if its CTC, signaled, yard limits, whatever. The yard lead (which is parallel to the CTC mains) is operated as track other than a main track. (Rule 105 in some books).

You also have to realize that the stop sign isn't a stop signal, its a stop and proceed signal. It doesn't hold a train there, the train on the yard lead could stop, see the train is stopped on the single track on the other side of the main and them pull across the single track line.

Personally I would put in a pair of dwarf signals on the yard lead that were set to display lunar normally, and stop if the route was cleared over the diamonds. Then the yard engine could make as many moves as it wanted in either direction over the interlocking on the yard lead, but when a single track route train operated the release and got the signal to come across the CTC mains it would put up an absolute stop on the yard lead and the yard engines would be prevented from blocking the single track.

Of course at this point just make it a full fledged automatic interlocking and be done with it. Then if all three diamonds are clear the single track train doesn't have to stop at all.

Dave H.

[lakinsa]

QUOTE: Originally posted by dehusman

Texas Zephyr wrote:
Personally I would put in a pair of dwarf signals on the yard lead that were set to display lunar normally, and stop if the route was cleared over the diamonds. Then the yard engine could make as many moves as it wanted in either direction over the interlocking on the yard lead...

Ok, that sounds that it will work. Can you point to a specific rule #/RR? The rule books that I have NYC/PC/CR and CSS&SB do not have any mention of luner indications. Just let me get this right... normaled, a lunar dwarf would be displayed in both directions. When the yard train passes the dwarf, entering the plant, they would both display stop. And they could make a reverse movement while still in the plant. When they clear the plant, the dwarfs would go back to lunar.

[Medina1128]

Huh? Man, whatever happened to setting some cars on the track and turning up the throttle? [:)]