My layout is fully controlled by a computer, so getting extensive train position feedback is necessity.  I have realized this with two Viessmann 5217 modules (equivalent to Märklin s88) and 30 self-made contact tracks.  The basic principle in the placement of the contact tracks is such that each section of track, which is separated from other sections by two turnouts in the ends, has one contact track in both ends. This allows the computer to know when a train has entered the section, and when it reaches its end, and is about to enter the next section or needs to stop.  The following picture shows how I have arranged the contact tracks on my layout. As you can see from the picture, I have also used contact tracks in dead-end yard sidings, so that the occupied tracks can be monitored. This also supports automated shunting operations on the yard.