PLBAB, Consider this: You have a double track loop with the inside loop containing all industrial sidings. Add two stub sidings at one end of the loop, one in each corner. For a given direction of travel, one would be a facing point turnout, the other a trailing point. With a crossover on each side of the loop, you can foul the outside line while switching the industries located there, and the train which was circling the outside loop can now crossover and run the inside for half of the loop, in effect running around the local. The other half of the inside loop could have cars sitting on it waiting for the local to return and finish the switching in that area. The added versatility of two crossovers will allow more interesting switching moves. Yes, the train which had been circling the outside loop could move to the inside loop for the entire distance with a double xover, but you would lose the ability to have cars set out on the other half of the inner loop. By the way, since I have become infamous for my support of DCC, this would be an ideal layout for DCC, allowing you to run the through train around a local without fooling with toggles. Depending on your pocketbook of course. It goes without saying that to run as outlined above, trains would need to be maximum length of 1/2 the loop length. Beyond that, switching trains from one loop to the other simutainiously would be difficult. But possible and yet another operating challenge.
Have fun, Gary