Portals with same train arriving three times .how to stpo 3 trains

[robynne]

Hi All,
Have just figured out how to make trains comes through portals but after setting up for one only locomotive as a test run, to come through the portal at a 15 minute interval. I now find that after waiting for that train to appear it does in the driver list but after few minutes the same train appears again. This train has now appeared three times. What have I done wrong?? If anybody helps me with this problem. Thank you ..All appreciated.. cheers, Robynne.

 

[stagecoach]

As the setting shows, it produces a train every 15 minutes. Every 15 minutes that portal will produce one of any of the trains in its list and will keep repeating.