Oslosl, you will probably find the following interesting:
https://wiringfordcc.com/intro2dcc.htm#reversing

 

Really, polarity matters even when using AC power to the rails. That is because some layouts cross the rails. American Flyer brand trains just used isolation sections that were always short enough to coast over. That does not work with simple DC power schemes where polarity controls the direction.

AND it seems that nowhere in this thread has the term "DCC" been defined! I have guessed that it mmeans "digital circuit control", but possibly not. I am reluctant to offer any more advice without knowing what is actually the control scheme. I have watched one VERY LARGEAND VERY DETAILED train system where multiple tranis could drive in opposute directions on the same track at different speeds, all atthe same time. (I was reminded to NEVER MENTION COST) in front of his wife.) So it is certainly possible to have total control somehow.
I am out of this discussion !

 

Really, polarity matters even when using AC power to the rails. That is because some layouts cross the rails. American Flyer brand trains just used isolation sections that were always short enough to coast over. That does not work with simple DC power schemes where polarity controls the direction.

AND it seems that nowhere in this thread has the term "DCC" been defined! I have guessed that it mmeans "digital circuit control", but possibly not. I am reluctant to offer any more advice without knowing what is actually the control scheme. I have watched one VERY LARGEAND VERY DETAILED train system where multiple tranis could drive in opposute directions on the same track at different speeds, all atthe same time. (I was reminded to NEVER MENTION COST) in front of his wife.) So it is certainly possible to have total control somehow.
I am out of this discussion !

Digital Command Control (DCC) is an advanced method of controlling model trains and accessories digitally. Unlike traditional analog systems, which use variable voltage to control speed and direction, the track is held at a steady voltage. DCC sends digital commands through the track. Each locomotive is equipped with a decoder that interprets these digital signals, enabling precise control over speed, direction, lighting, and sound.

 

If DCC is used to control trains, there still remains the problem of DC power reversal in double crossovers and P loops. These must be managed using a switched block system to avoid trains shorting the supply at the crossover points. This is most important with smaller scale layouts because the small, delicate power pickup contacts on the wheels can easily be burned off or welded to the wheel.