vette-kid - I think you are talking about grade crossing signals, I think everyone else in this thread is talking about ABS/CTC/Interlocking train "traffic control" signals. Vastly different scale of complexity.That's what I was getting at. You don't really need a block detection if your using optical sensors. A sensor on either side of the crossing, at whatever distance you want, will turn them on and off. Block detection is more reliable for sensing locomotives, but not cars.
This is theoretical on my party, since I havn't used these devices yet. But I would think a week designed board with optical sensors is all you need.
Some technically ability to do the wiring and installation, etc. and also some RR knowledge of how the signals work and which "pretty colours" are displayed in which situations, and where and how to located and configure the signal arrangements...it seems that layouts with functional signal systems either have someone with a technical background to help or the owner has a lot of patience to buy, install and configure commercial products.
Thanks for all your replies, It would be very complicated time consuming to redo my layout to go with blocks as ATS so I've decided to go with Z-Stuff their signals have built in sensors and also carry stand alone sensors so I can install them before the crossings,etc. it won't be prototypical but it's the best way I can think of to go at this time. Thanks again for all your advice. Bill OberstI want to install a operating signal system on my ho layout and wondered if any of you folks have had any experience with a particular brand good or bad.Thanks Bill
You are correct,I was taking about grade crossings. My bad. Although the boards in talking about seem to be made primarily for train traffic signals, at least a few. I don't really know much about that, so I have bothered with it.vette-kid - I think you are talking about grade crossing signals, I think everyone else in this thread is talking about ABS/CTC/Interlocking train "traffic control" signals. Vastly different scale of complexity.
Although even a grade crossing can be more complicated than that too - you can do a simple approximation with a simple on/off trigger circuit using a pair of optical or IR (infrared) detectors, but this doesn't account for real world situations like:
A "trigger on with one sensor/trigger off with second" or "trigger on and simulate with a timer/controller" circuit setup will simulate a crossing to the 80-90% point for a mainline crossing not near anything, but if any "work" events happen anywhere near by (including passing sidings or passenger stations where trains stop for a period of time) it's not perfect. We've been discussing a solution for actually lighting up crossing signals at a grade crossing on the club layout (which is located smack in the middle of a passing siding so features basically all of the scenarios above, plus having to account for BOTH tracks) and the current suggested design involves a long detected electrical block and IR sensors on either side of the crossing on the main track, plus IR sensors on each side of the crossing on the siding and a bunch of wiring/controller logic based on sensor inputs. Of course, being a non-signalled line, this is pretty much our simplest case... doing crossing detection on other parts of the layout that feature ABS/CTC signalling with detected track blocks for that causes additional complications for overlaying grade crossing blocks on top of that. We're figuring out that part...
- crossing signals trigger well in advance of an approaching train, but stop as soon as the train is clear the other side (so need at least 4 detection points)
- if a train triggers the approach signal, but then backs up to clear it (because they're switching something down the line) the crossing protection should stop
- if a train triggers the approach circuit, but stops and doesn't actually reach the crossing, the signals usually "time out" and stop. Signals start again once the train actually hits the crossing "island" circuit (moving very slowly and protecting the crossing per operating rules). Of course if the train stops ON or across the crossing, the signals should keep going indefinitely until the train actually clears
- a short train like a single car RDC or "doodlebug" passenger, or engines moving "light" or "van hop" will be short enough to be entirely between the sensors and not "seen"
Also, block detection is definitely the most reliable, but to detect cars you need to have wheelsets with resistors on all rolling stock that doesn't already have power pickup (e.g. lighted passenger cars). Depending on the size of your layout and rolling stock fleet, this is a whole project in itself. Detection can be approximated with optical detectors at block boundaries, but this will fail to "see" standing equipment between the block ends.
Detecting blocks and turnout positions for ABS signalling is another topic, and then laying on route control for interlockings/CTC is more advanced on top of that and pretty much universally takes computer control.