Traditional elevators with steel cables can do about 500m, carbon fiber cables well over 1km. Cable weight is not the reason for this. <br><br>Moving sideways with lifts? We have trains, moving walkways and lot of other solutions for this. Need to move sideways is not the reason for this either.<br><br>However, having 800m long elevator shaft in your building that has just 1 elevator car in it is horrible waste of space. What we really want is to put many elevator cars into that single shaft. Let's say 10. Why not 20? As then you cannot go up and down in same shaft anymore, you need two shafts: one for upward traffic," another for downward. And that's also where moving sideways comes in; you need to swap the car between the two shafts. As we see in the video here.<br><br><br>MULTI here provides an expensive solution", which still makes sense if you can fit lot of cars into those shafts. Instead of 8 elevator shafts in your fancy skyscraper, maybe you only need 4 now. Let's say the sky scraper has 150 floors and those 4 saved shafts take 10 square meters of space each to keep numbers simple: that's 150 x 4 x 10 = 6000 square meters of floor space saved from the building. Toss in 10k€ per square meter for value, and the elevator system could save 60 million euros for the builder. Even if MULTI costs millions more than regular elevators, there's plenty to spare. And there we have the true reason for it: money.