Detection

[wm3798]

Despite my best efforts to avoid needing much in the way of fancy electronics to run the newly configured layout, I'm running into a potential issue that I need to resolve sooner rather than later...

 

The issue occurs in the long, hidden siding that carries the Connellsville line under Cumberland.  It starts on the lower side of the peninsula, and re-emerges up by the window.  I'm using #10's here, and this is the only place that west end trains can meet between staging and the yard, so it's going to be a busy siding.

When I'm running through trains, they will have to pass through here in both directions.  I want to keep right hand running, per WM practice.  They did this on their remote sidings by installing spring switches.  Since the physics of N scale (particularly pilot trucks on N scale steam) don't allow for that in 1:160, I need to be able to create a route.

I think I can figure out how to do that with the decoder I picked up, but I also need to tell the train when to stop.  In the present configuration (using the #10)  The point of clearance that allows for safe passage is almost a foot behind the tunnel portal.  The opposite portal by the window will likely present the same problem.  I'm beginning to have night sweats about that.  I need to be able to see where to stop the train, and also to be able to identify when there's a train holed up in there.  I'm thinking a simple infrared reader would do the trick, but I've got zero knowledge of these things.

So, can some one point (or shove) me in the right direction?

Thanks.

[DKS]

My recommendation would indeed be a simple IR detector, and a big red light on a panel near the tunnel, or wherever it's clearly visible to an operator.

http://www.mrollins.com/irled3.html

[John]

I agree with David .. a simple IR detector would be your best shot .. I am going to do the same thing for my helix .. actually, if you look at this weekends update, BCR is doing the same thing ..

Now, if you actually ever intend to wire for signals, then you should start thinking about building in your wiring for block detection .. BEFORE you complete the scenery ..

[wm3798]

Okay, so being totally ******** when it comes to electronics, is there a commercial unit I can buy?  Oh wait, I don't have any money...  Better study the diagram some more...

 

So, let's carry this to it's next level while we're studying...

Let's say we've got some momentum built in to our locomotives... this would require a detector farther back to warn the engineer that it's time to put on the brakes, no? So midway through the siding, there would be a detector that would identify A) that your train is approaching, then give an indication of Red if the turnout is set against the train, or green if it's clear to proceed.

A further complexity:  Given that it's a double track section, there would need to be two detectors, and they would need to be set up so that if the opposite track is already occupied, the active track would still be able to "see" a train coming.

Hmmm.  I better get out a pencil.

Lee

[Bob Bufkin]

Did you ever think of hiring a midget to stand under there and yell out you better stop your train. ;D

[wm3798]

I'll get one of those low rider web beach chairs, Bob, and I'll set you up down there with a carbide light and a cooler full of beer...

Lee

[Bob Bufkin]

Nah, wouldn't work.  I'd fall asleep and my snoring would drive you crazy.

[DKS]

How about something a little lower-tech? Wire a section of track that goes dead to stop the train. A pushbutton restores power long enough to get the train out of the dead zone. Might not even need a detector at all...

[wm3798]

I thought of that, David, or even wiring the dead zone to the tortoise at the end, so if the switch is open, the track is "on".

But I have these recurring visions of a 30 car pig train lurching to an unceremonious stop, and spending the rest of the day picking trailers out of my teeth.

Here's the schematic... as I see it through my uninformed eyes.



So, going west to east, a train leaves the Connellsville staging yard, and arrives at Signal one.  This can be a simple switch indicator.  Open you get a green, closed, not so much.  But, Ideally this would be tied to the next siding... if switch at West Pinkerton is closed, it would indicate an incoming westbound train.  Thus the board at 1 would go yellow if the staging switch was open.

Here's the logic (I think)  We'll assume that westbound movements have authority over eastbound.
If 1 is open for an eastbound, and 3 is open, the board at 1 is green, and 2E is green
If 1 is open for an eastbound, and 3 is closed, the board at 1 is yellow and 2E is red.
If 1 is open for an eastbound, and 3 is closed, and the detector at 4 indicates a Westbound, the board at 1 is red, 2E is red, and the switch at 1 should be set for the westbound.

Once we're clear to enter the siding at Pinkerton, the detection becomes critical.  Since this is the "Fast Freight Line", the idea of a slow order through the tunnel is unthinkable, so the detectors at 4 will be critical.  If the switch at 5 is open, the detector would throw a green light out on the fascia, and the train moves along toward Maryland Junction, where it will await orders from the tower there to proceed to Cumberland for instructions on entering the yard.

If the switch is closed, the detector would throw a red board up, and the engineer would have to act to slow his train to a stop, with the detector at Five lighting up red when the lead engine reaches the limit for clearances.  Only when the switch is aligned for the eastbound will the red board at 5 come down.

At MY, the train enters train order territory, so no signaling is needed between there and Ridgeley.

Does this make sense?

Lee

[DKS]

I thought of that, David, or even wiring the dead zone to the tortoise at the end, so if the switch is open, the track is "on".

But I have these recurring visions of a 30 car pig train lurching to an unceremonious stop, and spending the rest of the day picking trailers out of my teeth.

FWIW, Rick Spano has a five-track staging yard that stores trains by cutting power. After running the yard for the last 20-odd years, he has yet to have a derailment owing to trains lurching to a stop.

[sizemore]

I thought of that, David, or even wiring the dead zone to the tortoise at the end, so if the switch is open, the track is "on".

But I have these recurring visions of a 30 car pig train lurching to an unceremonious stop, and spending the rest of the day picking trailers out of my teeth.

FWIW, Rick Spano has a five-track staging yard that stores trains by cutting power. After running the yard for the last 20-odd years, he has yet to have a derailment owing to trains lurching to a stop.

IIUC, there is the other horrible thought that if it's a three power consist of say SD-40's you'd be pushing dead units which is bad juju too.

The S.

[wm3798]

That's my main concern...  Lurching and stuttering as the dead units roll over the joint...  Under restricted speed this may not be a biggy, but this is the main line across the Allegheny front...

[sizemore]

Lee

If I understand correctly detectors cannot do direction, only occupancy. Emitters can set off detectors that are in close proximity. Detectors between 1-2 and 5-6 would be a single detector. The two emitters at #4 will need to face away from each other and have some sort of divider between them.

The caveat to the logic for automated running through the tunnel would be if the detectors at 1-2, 5-6 are clear, then throw the respective switch and give the green light based on frog polarity assuming the use of Atlas/ME switches.

If the switches were the same switch type (left-left) you could use sprung switch enforcing right hand operation in each direction. The problem would be frog polarity, if you're using PECO you can get away with it. If you're using Atlas/ME you could potentially finagle a reversing circuit to throw the polarity on the frog.

I could be completely wrong...I'm still trying to wrap my head around a solution....

The S.

[DKS]

How about making the dead zone more intelligent. Keep it live. Use an IR detector to sense when the train has reached the point of no return, then have the IR detector both kill track power and send up a smoke signal (big red LED). Easy to do:

Original IR detector + small relay + input from Tortoise (to see if the route is set the wrong way) = intelligent (relatively speaking) control.

[wcfn100]

I think I would go with two detectors per track with a signal track side on either end.  The detectors would guard the clearance points of the sidings.  As an operator, once you clear the first turnout, you simply stop your train.  The second detector will tell you if you went too far.  If either detector is covered, the signal for the oncoming train will display red.  This will also tell the operator that he went too far and has to back the train until the signal goes green.

The biggest hole is that there could be a situation where you don't know if a train is in the tunnel.  Obviously there are ways to deal with that if need be.


Jason