AI Train from portal not working

[richardm773]

Hi, I'm using a revised built-in route to run some AI trains. The route has parallel tracks running North/South with a portal at each end and
junctions near the middle to allow trains from both tracks to travel west to a couple of stations X and Y. They then return to their original mainline to exit via the opposite portal.

Each train has an allocated driver and schedule and is produced every 15 minutes from each portal as follows:

Train 1 travels from the south via A & B and exits north taking around 28 minutes.
Train 2 leaves 15 mins later from the north via A & B and exits south also 28 minutes.
Train 3 leaves 15 mins after Train 1 from the south and goes straight through to exit north taking about 6 minutes
Train 4 leaves 15 mins after Train 2 from the north and goes straight through to exit south also 6 minutes

However, while Trains 1, 2 and 3 follow their schedules perfectly, Train 4 exits the north portal and then comes to a stop.
The driver disappears and is replaced by a ? After that there is nothing I can do to get it moving again. None of the other trains
are blocking its route and no messages appear on the message board to indicate that anything is wrong.
I would be grateful for any help resolving this problem.
Thanks, Richard

 

[shaneturner12]

Have you tried using a different driver, or checking if there are any differences in the commands?

Shane

 

[iannz]

Is it possible there is an unsignaled junction along the route?

 

[richardm773]

Have found an invisible signal which I removed from the route then changed the session schedule around so that the 1st and 3rd trains came from the north portal and the 2nd and 4th from the south. I also changed the driver on the 3rd train. However the 3rd train from the north still stops after leaving the portal but this time the driver remained intact but the schedule disappeared. I re-entered the schedule in the empty box and the train then continued to the south portal as originally intended. Not sure removing the signal had any effect.