I'm looking for ideas on how to control a serial staging yard on a DCC layout.
The staging yard is a hidden 88 foot long double track reversing loop that is always traversed in the same direction (counterclockwise). Each track is planned to have six ~14 foot slots for trains. The yard is located 4 to 8 inches below the main level of the layout (with only scenery sections that are removable for emergancies above the areas with 4 to 6 inch clearance). Normal viewing underneath the main 41 inch high level is comfortable sitting in an office chair.
At the start of an operating session I intend to have six trains on one track and six empty slots on the other (which fills up during the session). My current plan is to have each slot controlled by a DPDT on-off-on switch (labeled: IN-OFF-OUT) to both control the polarity and shut off the power to stationary trains. At the start of a session the six switches for the track with staged trains would all be OFF and those for the track with the empty slots would all be IN. With walk-around control using radio throttles, I plan on putting the toggle switches under the fascia at the clearance point for each slot. Since it doesn't seem prudent to try to stop a locomotive that suddenly appears at the front end of a slot, I plan to put the toggle switches at the back end of each slot. That way the operator can watch the train appear and has time to slow the train down and stop with the caboose shortly beyond the clearance point.
While this approach works for an attentive owner-operator, I'm looking for ideas that would: 1) inform that the next slot is occupied (or turned OFF) and 2) more importantly, prevent an inattentive engineer from running an inbound train into an occupied slot.
Thanks
Grinnell Jones
I have just built some infrared detectors from plans kindly offered by Robert Frey
http://cs.trains.com/trccs/forums/p/160848/2048740.aspx#2048740
They work quite well and are easy and inexpensive to build. They may do the trick for you at least as far as detection goes. One thing to note is that they won't work with incandescent lamps overhead, but in your staging area that likely won't be a problem. There could be an issue where you only have 4" of clearance above the tracks. They may sense the structure above and give a false reading.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Grinnell,
I can see that you have put a lot of thought into this. The toggles will handle the reversing loop electricals, and also give a 'dead stop' for each train. I still have concerns about running in your staging 'blind'. I would use 'infrared' photocells(IR detector) that are not tricked by light leaks. Place them about 6" before the next train section and they can turn off the power automatically. the toggle can be used as the 'override' to bypass the IR detector and allow you to move trains onto the actual layout.
I have 4 parallel staging tracks that use IR detectors for the 'end of track' in each direction. Since the staging is in the 'open' - normal photocells would not work very well(and there are issues with low light). My new 'retirement' layout will have 10 tracks that are about 16" below the main layout - all 'visual' detection staging!
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
jrbernier I would use 'infrared' photocells(IR detector) that are not tricked by light leaks. Place them about 6" before the next train section and they can turn off the power automatically. the toggle can be used as the 'override' to bypass the IR detector and allow you to move trains onto the actual layout.
I would use 'infrared' photocells(IR detector) that are not tricked by light leaks. Place them about 6" before the next train section and they can turn off the power automatically. the toggle can be used as the 'override' to bypass the IR detector and allow you to move trains onto the actual layout.
I'm confused, you seem to be detecting the arriving train and shutting off it's power. Why do this at the last moment? Why not use a dead zone and let the train run into the dead zone. Now if you used the detector to have the stopped train automatically shut off a dead zone behind itself (and stop the next train), we might be able to make this more 'fool proof' (although we'd have to figure out a way to make it turn off only if the block ahead is turned off, which is already starting to make my head hurt just thinking about it!)
A first improvement (complication?) to my original approach would be to use 2 DTDT on-on toggle switches for each slot. A miniature toggle (labeled: IN-OUT) that controlled the direction/polarity that was set before the session that was fed by another full size toggle, used during the operating session (labeled: ON-Protect) where one pole cut one leg of the track power and the other pole would at the same time energize lamp power to a 'next slot occupied' light at the toggle switches for the previous slot.
A second improvement (complication?) would sacrifice a foot of train length so we would have 13 foot trains in a 14+ foot slot with a foot or more dead zone behind each train. This would allow you to accidentally (or blindly) run the next train into the dead zone. The operator would still have to manually turn off the power afterwards to protect his train by establishing the next dead zone. A down-side of 'dead zones' with DCC is that the last condition of the locomotive decoder could be 'running', which leads to surprises when the dead zone is re-activated. Setting up for the next session would be a little more complicated, because we could have 2 locomotives in the same slot, so I'd have to remember to command both to stop/shut-down before temporarily turning the power on.
Good ideas folks, keep 'em comming.
I was thinking about an 'overlay' safety with the dead zone. If a train is in the first dead block ahead of you is really filled up the 14-15 - a multi-unit diesel might have the trailing units 'push' the lead unit into the train ahead. If a train is in block 1, and the next train is arriving in block 2, why not turn off the entire block 2 when the first engine /car trip the IR Detector? That way, the entire block is dead - the only way to power it would be the operator flipping the toggle to power it on. Also, by have IR detection, you can 'see' where the trains are, and not have to 'remember' where they last were.
A friend has hidden staging and uses an inexpensive security TV camera system to 'look' at his staging, There are 4 small cameras with the system and he can view from several angles.
Dead sections are great, but they do have one problem - multiunit consists with more than one powered unit will simply get 'stuck' as the lead unit(s) hit th dead spot and the trailing ones are unable to push the dead powered units and pull the rest of the train. Someone not paying attention could leave a train sitting there thinking it properly stopped in position on the staging track and if the throttle isn;t shut down leave the last powered unit sitting there grinding away.
Combine the IR detectors with a relay to control the dead section, which would be as long as the longest consist you run. A momentary (spring return to center) toggle could bypass the relay contacts. So you drive the train in, and when the lead unit passes the detector, it trips the realy, killign power to either the whole track or a section long enough to contain all powered locos. To leave, the appropriate toggle would have to be held until the train cleared the sensor.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks, you've convinced me that 'dead sections' are a bad idea. However, IR sensors and relays seem awfully complicated. More importantly, they still have a failure mode that someone forgot to turn on the sensor. We've spent alot of energy on electronics and traded one "I forgot" for another.
Perhaps my second requirement in the original post "prevent an inattentive engineer from running an inbound train into an occupied slot" is unreasonable. After all on the rest of the layout we trust the engineer not to run into other trains or over-run his clearance from signals or the dispatcher. Having a toggle switch that both kills the power to my train and "flags the rear" seems more like a railroad type of operation (similar to placing a torpedo on the rail). The only problems are that my railroad empire is self-insured and I'd hate to have to fire myself for a "senior moment".
Grinnell
Why should anyone be turning a sensor on or off?
The IR detectors should always be on so you can see where things are parked in the staging yard.
On the staging yard at our club, we have a pair of detector/indicators at the end of each track. One to indicate when an engine is nearing the end of the track and one to indicate when it's gone to far. The train should always be parked so that the first panel light is on, but the second is not.
Here's a pic of the control panel, you'll see three lights at the end of each track. Yellow for switch routing, red for the fouling point detector and green for the "good" stopping point detector. (The power to the LEDs above the dectectors was off when the photo was taken, so the detectors are not actually correctly showing what's down there.
Chris van der Heide
My Algoma Central Railway Modeling Blog
cv_acr Why should anyone be turning a sensor on or off? The IR detectors should always be on so you can see where things are parked in the staging yard.
I over-simplified the situation and caused confusion. You need to have the "automatic-shut-off" feature associated with the IR sensor inactivated so that a train can proceed through a series of empty slots until it gets to its appropriate 'parking' slot where you want the auto-shut-off to actuate. So far this activation and de-activation of the "automatic-shut-off" feature is still a manual operation.
Now that I think about it more, the sensor driven auto shut off eliminates one of two failure modes in my manual system: the engineer drives past the fouling point problem. Both systems still have a common failure mode: the operator fails to "protect" his train after parking it (by turning on either an "occupied" light or by activating the sensor driven auto-shut-off feature for the trailing slot).
I suppose the ultimate solution is for the auto-shut-off to also automatically turn on the auto-shut-off feature in the preceeding block. As a systems engineer I can come up with the requirements, I just don't have the knowledge and skill to execute them.
That is a nice control panel depicted in the previous post, very well executed. A good solution for manual control of a completely hidden staging yard.
SHould eb no problem with 'forgetting' the sensors - power them from a wall wart that powers one when you turn ont he rest of the layout. If you don't have a switch outlet for your layout, you can get an X10 appliance module and one of their keychain remotes - this is how I turn mine on and off, so I don;t have to crawl under the layotu and turn the power strip on and off. The X10 module (has to be an appliance module - for just on/off action, no dimming!) feeds a surge protector to which I have my power supplies plugged in to. One press of a button (I usually leave the remote ont he corner of the layotu byt he door) turns it all on or off. I actually have another one feeding a power strip for my work bench, I leave my magnifier light switched on all the time, so I can tell at a glance if there is power at the bench - turn it off, the light goes off, and I am confident knowing everything else over there is off too - like my soldering iron.
SO - turn ont he layotu to runt rains, the IR sensors are powered. Nothign to forget. The bypass toggles should be momentary - have to hold them down until the power is out of the siding. Failsafe. The circuit isn;t complicated, you can use commercial IR detectors, the output feeds a realy, the realy is wired to the track exactly liek you'd wire a toggle switch to manually cut power. That's all relays are - switches that cna be activated by another circuit instead of you moving a handle.