View Full Version : Problems controlling junctions with AI trains

August 13th, 2015, 12:15 AM
Hi, I'm trying to run 4 trains using AI over a cycle of around 30 minutes. They sometimes use the same junctions and are triggered by other other trains at various points in the layout. It seems to be a completely random process as to whether the junctions change correctly to allow the trains through or simply don't change and bring everything to a halt. I've tried the Control Junction, Free Junction and Release Junction driver commands but again they seem to work totally randomly and will sometimes allow trains to continue and sometimes not. Is there any way to resolve this or is it commonplace with AI?

August 13th, 2015, 12:52 AM
What it seems like to me you need to place Track Markers and then select either drive or navigate via the "Track Marker" name. This seems to solve my issues but try experimenting it.

August 13th, 2015, 08:30 AM
Yes, all my routes are either drive or navigate to or via Track Marks or Industries which sometimes work and sometimes not. For example I have a loop siding on a single track to allow trains to pass one another. As the "up" train passes it triggers the "down" train to leave the loop and continue to an industry, The up train sets the junction against the down train which, when triggered, will sometimes continue down the line and sometimes will just stay in the loop. I've tried controlling the junction via the down train commands and again this sometimes works and other times not. I've also tried releasing or freeing the junction via the up train but not quite sure how these are supposed to work or where you are supposed to place them in the driver's commands. Anyway, thanks for the reply and I'll continue to experiment.

August 13th, 2015, 11:56 AM

You may want to try one of the path-control rules and driver commands. I'm sorry but I can't help you with them as I've never used them but only read about them. These will allow you to lock the route for your particular driver and prevent others from taking over.

What you are experiencing with your drivers is something that's been an issue for years. Another driver could grab the junction a split second ahead and lock it for its self. which is the normal thing. The problem is the following train for some reason doesn't take the junction and flip the points for its self in the other direction, and instead continues down the same path. The problem then is your following train goes the wrong way, faffs around and screws up the works. I once had some trams get lost. One actually ended up down on some docks way off its own route. The dock branch was used by some shared ROW with a diesel switching operation. The tram driver happened along a split second behind the diesel driver and ended up giving the passengers a special tour of a non-revenue line. :) The problem though this faffing around seems to cause awful performance as the AI get stuck and attempt to get themselves back on track, pun not intended.

In the end I staggered the following trains by using a wait... (choose your time) driver command. The interval was only 5-seconds and that was enough to prevent this from occurring again. You could even try this first, it's a lot less complicated, and see if it works for you too.


August 14th, 2015, 05:22 AM
Hi John, thanks for the information. I already have various "waits" in the driver's schedule to give the other trains plenty of time to get well clear of the junctions and sometimes they work and sometimes not. I'm not sure how the Free Junction command differs from the Release Junction command but have assumed that Free Junction applies to the train that has just passed the junction and the Release Junction applies to the train that's waiting for the junction to clear but I'm not sure. Also, whether you place the Free Junction immediately after the Control Junction command.

I will try to find out how the path-control works but from what little I've read it seems pretty complex. Anyway, will keep plodding away and hopefully find a solution eventually.

Many thanks, Richard

August 14th, 2015, 07:33 AM
ReleaseJunction (https://www.auran.com/TRS2004/DLS_viewasset.php?AssetID=375718) is paired with WaitForJunctionPermit (https://www.auran.com/TRS2004/DLS_viewasset.php?AssetID=57630)
FreeJunction (https://www.auran.com/TRS2004/DLS_viewasset.php?AssetID=68474) is paired with ControlJunction (https://www.auran.com/TRS2004/DLS_viewasset.php?AssetID=68476)
The descriptions explaine the use of these commands.


August 15th, 2015, 01:37 AM
Thanks Peter I didn't know about the Wait for Junction command so will give it a try although it might not suit the situation as it seems the route has to be totally run and cleared by one train before another train can start out.

Regarding the Control and Free Junction commands, do you know how they are placed in the Driver Command List? For example a train leaves A and navigates via one trackmark to B. It passes through 2 junctions on this route, one before the TM then one after. Do I put the Control and Free Junction commands together before the Navigate to TM command to control and free the 1st Junction or do I put just the Control Junction command before the TM and the Free Junction Control after the TM? I seem to have tried lots of different variations but wondered if there was a definite rule in placing these commands.