Oops, I jumped the gun...I hadn't seen the revised version. Looks much better. And, yes, that leg of the "Y" (the red section) does need to be isolated at both ends. Also, if you use DCC, the length of the trains may be limited to the length of that section, since the automatic reversing modules which you can use to control that section work on short-circuit detection, and longer trains may cause the controller to trip more than once, bringing your train to a screeching halt, or causing it to go in reverse when you least expect it. Gus.