Crossovers - stopping trains colliding

[pauldurose]

Hi all, apologies if this has been asked before but...

I recently made a crossover, each leg is protected by a signal, but in AI a train can still be allowed to cross at the same time as another as presumably the simulation doesn't 'see' the other train as it's not actually on the same line.

Difficult to describe, sorry! Here is my crossover: -
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/ \
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^^
Two trains approaching from bottom (^), one on each track, switch set to opposite track. Signal sees 'green' with feather to opposite track. Trains 'collide' on the crossover.

Basically, is there any crafty way I can avoid this happening? I know I could work the AI to avoid the trains needing the path across the crossover, but this isn't always possible with AI.

Thanks.

 

[Michael_Evans]

there is a crossover rule on DLS or you could place trackmarks at the crossover and stop the trains at the trackmarks and use the waitfor, or waitfor trigger commands

 

[pgmetcalf]

Or you could use invisible track junctions and link them with the junction box. Below is a map shot of the route I'm currently working on. OK it's not a diamond junction but you get the idea. The green arrows show the direction which the point is set at. The 2 bottom junctions are the invisible track points.

 

[omber]

I tried using junction link to do this but it seems AI can change the linked junctions even though train is passing over one of them, derailing the said train.

 

[pgmetcalf]

I tried using junction link to do this but it seems AI can change the linked junctions even though train is passing over one of them, derailing the said train.

But in the diagram I shown there is no chance of that happening because the same junction may have more than one junction link. This means that if the junction forces train one way it flick the switch on the invisible track to open (end of track) meaning the signal is red thus stopping the trains. believe me, it works.

 

[pauldurose]

Thanks - but stupid question, how do you link junctions?

 

[Dermmy]

Thanks - but stupid question, how do you link junctions?

with Mizi's "Junction Link" on the DLS here.

Andy

 

[Red_Rattler]

I believe that I may have one of the solutions to this subject. I will get back to you later.

 

[Lynxfan]

I tried using junction link to do this but it seems AI can change the linked junctions even though train is passing over one of them, derailing the said train.

You have to link the junctions twice (j1-j2 and j2-j1), especially in a crossover. Otherwise when the train clears the first junction and returns to default the second junction follows thus derailing the last car or cars.

Oops. I didn't read the the original post first. This solution is for a crossover not crossing tracks. The diamond crossing fix needs to be used for crossing tracks and that is tough to get right.

 

[pauldurose]

Question about Junction Links

Thanks everyone - particularly Dermmy for that link.

I think I've sussed it now, using a combination of Junction Link and a Junction Control box. The links keep the opposite switches together, and the Controller keeps the 'straight on' line switched away from the crossover meaning the relevant signal sees Red. I haven't explained that very well, but it seems to work.

Imagine the crossover is like my original post, but with 'straight on' tracks as well, with switches labelled 'N', 'S', 'E' & 'W' and a signal for each approach (with feather across the crossover).

N E
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W S

I've used 4 'junction link' boxes: E-W, W-E, N-S & S-N (which being doubled-up will hopefully stop the rear switch resetting to default before the train has passed - not sure until I test it out), plus 1 'junction controller' box set as: 'If W is Right then S is Right', and 'If S if Left then W is Left' (which holds the other path closed; seems to work).

Quick question about these Junction Links - what governs their use? I've put some others on my layout but not all work. Is there a maximum distance between linked switches? Or perhaps a maximum number of boxes per layout?


Btw, happy new year to all.

 

[Accipiter777]

Easy solution.... "ControlTrackAtTrackmark" command and "FreeTrackAtTrackmark" Command...

Place a trackmark on the both tracks leading up to the crossover.

we'll say one is "A" and the other track "B". then place a trackmark at the Crossover itself for example "Crossover". on the other side we'll have "C" and "D".




One Driver heading to "A" and the other heading to "B"... Schedule would look like this:

Drive To Trackmark: "A"
Control Trackmark: "Crossover"
Driver VIA Trackmark: "D"
Free Trackmark: "Crossover"

other would look the same, 'cept he'd move from B to C

whoever gets there first, goes first.
the other cannot go untill the first not only free's the "Crossover", but the train must be clear of the Trackmark as well. this set-up is what i use at all major interchanges. in some cases, i have AI control several Trackmarks before moving on. I also do this for single tracks that get used in two directions.

 

[stagecoach]

Trigger multiple signals can also be used. If the last diagram showed A, B, C and D as signals and two triggers placed one on each track at the crossover point (or even two on each track before the signals) any train going from A to D would set B and C signals to red and vice versa. This would be set up in the trigger multiple signals rule.

 

[Red_Rattler]

** NO QUOTING of images **
Try this for a test:
This is one of my solutions, & just moving the tracks, signals, etc to suit the route. Make sure the junctions are set as shown, but I’ve since changed the two invisible tracks to one for a simpler set up.


To test the setup
Create a new map, run a track from each corner to form an X. Add some extra squares to each side (one extra on each side is plenty). Then place two trackmarks, invisible track, signals & two trains of the exact same type as shown below. Make sure that the two trackmarks & the two trains are the same distance apart from the crossing of the tracks. For the signals use semaphores & not lights, so you can see what the signal shows looking at if from behind.

In the Driver Setup use these commands:

1st train:
Wait for 5 seconds,
Drive to trackmark (in this case Trackmark 2)

2nd train:
Wait for 10 seconds
Drive to (This case trackmark 1)

In the session, one of the trains should give way to the other. For other routes you should be able to do a similar setup, but adjusting of course to suit the route.

 

[pauldurose]

Thanks again everyone. I've been trying to do it so it all works automatically without the need to write it into schedules.

For info, this is the actual track layout I have: -

 

[rroby]

I have a very similar layout in one of my coalmine yards. I've used the Junction Control V2 (kuid:122381:10005) to set up the following “routes” thru the crossover.

Link J1 and J4
If J1 L then J2 L
If J1 L then J3 L
If J1 L then J4 L
If J1 R then J4 R

Link J2 and J3
If J2 R then J1 R
If J2 R then J3 R
If J2 R then J4 R
If J2 L then J3 L

Link J3 and J2
If J3 R then J1 R
If J3 R then J2 R
If J3 R then J4 R
If J3 L then J1 R

Link J4 and J1
If J4 L then J1 L
If J4 L then J2 L
If J4 L then J3 L
If J4 R then J2 R

I haven’t tested it out on AI trains yet, but so far it’s worked OK for me with the signaling. You do need to use some invisible signals.

I’m planning on running a few AI tests this weekend. Will post my results after I’m finished.

 

[Red_Rattler]

If it's not based on a real railway would it be an advantage to move one of the arms of the diamond to form a crossover?

And the station with the diamond crossover, is it a terminus or through station?

Trigger multiple signals can also be used.

I haven't figured out how to use that rule yet, even after following the instructions!!!

[video now deleted]

PS: It seems as capital letters such as FgHjKLm is different to fghjklm in Youtube's URLs.

 

[pauldurose]

If it's not based on a real railway would it be an advantage to move one of the arms of the diamond to form a crossover?

And the station with the diamond crossover, is it a terminus or through station?

It is a real world layout - through station. The real station has only one through platform which works as two separate platforms - one at each end - with the crossover to allow trains to pass. The extra platform on the right of my posted screenshot is a fictional addition. (See my 'Cambridge' post for more).

Real version: -

http://maps.google.co.uk/maps?f=q&hl=en&geocode=&time=&date=&ttype=&q=cambridge&ie=UTF8&ll=52.194088,0.137675&spn=0.000393,0.000904&t=h&z=20&om=1

 

[stagecoach]

Red_Rattler
As a test for the trigger multiple signals rule place a double circle track on a base board. on one track place trigger and give it a name. on the other track place four signals and give one a name, (The other three is so the engine wont see itself). Open the edit session and select the trigger multiple signals rule then open with edit. You have the option to select a trigger, click the select trigger and then the trigger you want (in this case the only one you have) then below select the signal the trigger controls. by clicking the right hand side of the listed signal you can select red, caution, green or automatic. select red, this will cause the signal you selected to stay red while a train is detected by the trigger.
Place an engine on each track making sure that the engine on the track with the signals is facing the signals correctly. Go to driver and ask the engine on the signaled track to just drive, then move to the engine on the trigger track and drive it yourself around the loop. You should see the chosen signal change to red if it is not already, or stay red when the other train approaches the signal. It will revert to automatic when you drive out of the triggers range so releasing the other engine.