I'm blocked at work from any videos or photos but if you google "segundo piso periferico", Mexico City added a second story to one of the main routes (not rail, though). If you've ever been in Mexico City, the magnitude of a project like this, logistics and chaos makes many other projects pale in comparison
<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>