That would be the aforementioned 4-wide train track. It originally was made in dark bley for the Temple of Doom mine cart set, and then was used in black for the Alien Conquest mother ship and a Joker funhouse, before showing up in Friends last year.
I have a *lot* of this track in black. The big drawback to it is that it comes in just two different parts and neither one is a straight track. I don’t have the Friends set, but I am also wondering how easily the train derails as the hills get bigger. I was doing test builds using the large-diameter Mindstorms balls and all it takes is a single descent and a curve to make the ball jump the track, I had to manually slow them down on the descent. I did not get around to simulating a straight track using the old-style train rails, but the gap created in the rails by doing so would almost certainly not work for a rollercoaster. For the Joker Manor, they’ve created new train parts that clutch the sides of the rails.
I am looking at the Joker Manor pics on lego.com, and in the pics I can see five different types of parts (I’m finding no pics of the back of the build other than close-up interior shots, so I don’t know what the rollercoaster is doing back there). For the big drop, the way the pieces are designed, it looks like the length of the drop could be extended to any length desired if Lego created just one more straight descent piece to put in between the two.
Given these new pieces, the success of the Ferris wheel and carousel sets, Lego’s lack of shyness in recent years about releasing increasingly large and expensive sets, and the fact that at least one of Lego’s rollercoaster competitors was moving sets at BFVA17, I have to wonder if a big rollercoaster set is on the way from Lego in the next year or two. It could be wishful thinking on my part, but at this point I wouldn’t be surprised if it happens.
I go out of my way to not look at pics of sets I plan to buy so I won’t get spoilers before I build them, but I’m still with Phil on this one, if somebody wants to bring it to Q4, I’ll check it out.