Hi, thanks all for the input. For any one interested, I use a 'Token' method to get round the AI at times.
I know of 2 simple 'Token' like methods for controlling access to sections of track.
These have appeared in the forum.
Event method
1. create a circular track in a fiddle yard (A Fiddle yard is used in model railroading where excess rolling stack is parked. Model railroaders always have more rolling stock than they can fit on a layout
).
2. Place Destination marks at various points of the compass - say 90% apart for 4 points N, S, E & W.
3. Place a 'Raise Event' command after each Destination Mkr. - say events 1-4.
4. Place a loco on the circle and set a command line to 'Navigate via' each Destination mkr in turn. (Don't forget to place signals to get the loco moving)
5. Vary circle diameter and loco speed to get the loco to trigger the events - say at 20 seconds apart. For 4 equidistant points this is an 80 second circle.
6 Use 'Wait for event x' to trigger actions in each AI train command line as needed.
This can be varied to suit but does need a driver for AI.
You could also do a reverse by triggering the loco to start from an event outside of the loop.
Junction Permit method
1 create a 'Fiddle yard' track not connected to the layout track.
2 add junctions as needed and name them. eg 'Token Yard'
3 For each AI train, add a 'WaitForJunctionPermit'-'Token Yard' command line, after a 'Navigate To' before entering the 'Yard' and add a 'ReleaseJunction'-'Token Yard' after leaving the yard.
(These are old and give warnings when downloaded in TS12 <kuid:131986:210011>,<kuid2:131986:210012:1> (Thanks for these go to author atilabarut)
Note: This method does not require a train to 'pass' particular triggers/ markers/ junctions to set/release.
AI trains will wait for the 'Token' to be passed each time it is released.
You still need to keep all existing 'in yard' rules.
EVERY AI train using the yard needs to use the same 'Token'.
I also use a combination of HoldJunctionOnly, ControlJunction, FreeJunction & HoldJunctionWithTrackExt
<kuid:131986:1011>,<kuid:131986:1022>,<kuid:131986:1073>,<kuid:131986:1089> again thanks atilabarut
These get complicated in setting up but work near 100% of the time.