“Suburban Line” is a fantasy line and is part of a trial as I am new to the software.
There is a timetable included in which the trains start at three locations, Ash depot, Elm sdgs and oak sdg. After these have appeared the service settles down to a 5 minute arrival and departure at Ash.
You can set up the line for automatic signalling if you wish but this will in fact cause delays! Use the platform loops at the stations to keep the services moving and the trains on as many proceed aspects as you can. Any delays will have a detrimental effect on your performance.
As this is a test sim please let me know of any issues. I will be working on another timetable with express services, which will make the sim even busier and also ensure that more train control is required. Besides that have fun.