Any time I replace or lay new track, I first fit it and tack it down to test it. I use a locomotive that finds all the track flaws (we all have at least one! 😅) and run it together with the biggest cars. In this case, I used ClassOne Model Works’ auto parts cars. The two versions here have square coupler pockets as opposed to the swing couplers on some other road names. Then I run the consist at full speed through the new track, backwards and forwards. If it derails, I will run the train slowly