Do you have a turntable that indexes by itself? If not, then a rotary switch might be a good idea, depending on whether you can find one with enough positions and contacts. I used to use a 2-deck 2-pole/deck 8-position rotary switch to select blocks on my old DC/block system layout. This switch had make-before-break contacts so there would be no interruption of power as a train crossed from one block to another. Not sure where you'd get such rotary switches anymore. Probably on the internet.