Automatic signalling on a dual loop (DCC) layout

[berkshirebugsy]

Hi all - I hope this is in the right area of the forum.

On YouTube there are lots of good videos on how to automate signalling using Arduinos. They seem to be based on different forms of block detection - I understand this. Some of them work on the principle that once a train has been detected then the lights will go through their sequence (example, red, orange, green) on a timer basis. Some of them are a bit more sophisticated and will change the state of a previous signal (for example from red to orange) when the train moves from one block to the next. I also understand how this works.

This is where it gets difficult more to explain what I want to ask!

Consider a layout with two concentric ovals of track with points connecting both ovals. My understanding is that in the real world if a train moves from the inner loop to the outer loop then the signals on the approach to the points on the outer loop will be set to red (and the previous set orange). Has anyone come across a DIY system that will manage this? Can it be done via detection in JMRI?

Thanks for humouring me
Dave

[Tricky Dicky]

I am not familiar with JMRI and so do not know what detection methods apply although I believe you can script your own. As far as a hardware method there are two approaches. The first is to let the train indicate the route it is going to take, this can be using a IR LED fitted to the underneath of a loco using the decoder to switch it ON/OFF as appropriate a IR detector set in the track could then be used to change the opposing signal.

The second could work using some of the commercially available detectors such as Heathcote circuits but activating the circuit from the movement of the point to detect the oncoming train the downside is that the signal would not show until the point had moved and the train had triggered the detector which is not the way it happens in the real world.

Richard

[berkshirebugsy]

Thank you very much - that is very useful

[jed10]

Take a look at the Block Signalling IR sensor modules which will work standalone.

[Brian]

Being pedantic-Sorry UK railway colour light signals show Red/Yellow/2 x Yellow/Green aspects. Not an Orange aspect!
Road traffic lights show an Amber light
The aspects are arranged so as the most restrictive aspect is closest to the drivers eye line. Usually Red at the bottom of the signal head then first Yellow and Green above that. On four aspect signalling a second Yellow is fitted above the Green. Occasionally where a signal is ground mounted (in tunnels for example) the aspects are reversed with the red at the top again nearest the drivers eye line. Modern LED lit signal heads will have just one or two aspect lens. The lower, or only one lens signals, shows red, yellow and green through the same lens. Where four aspect signalling is used then a second LED aspect lens is fitted above and only shows a Yellow as the second double yellow aspect, otherwise its extinguished.

Your signal sequence automation will need some form of train detection - Infra Red, Reed swich and magnet on every loco (not the best option IMO) or DCC "Train of Track" block detection. You will also need point blade position detection too, to allow the Junction Indicator (Also known as aa Feather) to illuminate on the approach signal to the points or use a side by side twin head signal. The controlling signal will be put to red as the train operates block section between the point and after passing the controlling signal thereby also turning the signal in the rear to Yellow
The J/i or Feather will operate via the point position switch and illuminate when a proceed aspect is displayed on the controlling signal. The J/I does not light when the signal is at red except when its turned On to prove the diverging route and ensure the correct minimum number of lamps are lit before the proceed aspect is lit. A dual head signal will need the main line aspect to be at red while the diverging routes signal is at Proceed aspect when the route is set for crossing over.

BTW your understanding of UK signalling is good but not quite 100% correct! It all depends on line speed. So for slow speed turnout then approach control is used to hold the controlling signal at red then when the train is detected approaching the red aspect and the line ahead is clear, after a pre set time period the Controlling signal clears to a Yellow proceed aspect once the J/I is proved lit. The signal in the rear following with a Yellow when the controlling signal is at red. The signal in the rear of course goes to red after the train has past this rear signal and remains at red until the section between the two signals becomes clear (no train). Where high speed turnouts are used and the turnout route is at a lower speed than the main line then signalling can be cleared to a proceed aspect on the controlling signal and the J/I is proved lit. On modern HST lines or lines usually over 100MPH flashing yellow aspects are now used to pre warn drivers to the approaching turnout one or two signals ahead of the Controlling signal. e.g Three aspect signalling a Driver sees. Green then the next signal is a single flashing Yellow, then a single Yellow steady aspect and then over the points to the diverging route. On four aspect signalling the Driver sees.. Green. next signal at 2 x Flashing Yellows then the next signal is a single flashing Yellow and then the Controlling signal is at steady Yellow.
To note the "Controlling" signal is the one just before the diverging pointwork.