This is a cool idea. But looks VERY expensive..,(reply>), Think about how it could benefit a building like the burj khalifa. It currently has an insane number of elevator shafts, plus two separate elevator systems that require you to get off of the elevator halfway to board another if you're going to the higher floors, simply because of the weight of the cables. In such large buildings, the maintenance a system like this requires would pay for itself merely because of the floor space you save and can then rent out to more customers. Since you can have a large number of cars in each shaft, you may only need a total of 4 shafts, two up, two down that run the entire length of the building and could easily handle the traffic. Safety is also not much of an issue with this, since the brakes actually require electricity to stay OPEN, plus when the car is in freefall, the liner motor actually generates an opposing magnetic field in the track which produces electricity and would slow the car down quite a lot, lust like a magnet falling through a copper tube. Also lets the cars recover some of the energy the spend climbing while traveling down.