No time to dig on this, but "Elevator at one of Chicago's tallest skyscrapers plunges 84 floors after cable breaks"
https://www.foxnews.com/us/elevator-at-one-of-chicagos-tallest-skyscrapers-plunges-84-floors-after-cable-breaks
>“That rope is one of several that are connected to the elevator, and, even with this one failing, there’s a redundancy in place," City Buildings Department spokesman Gregg Cunningham told the paper. “Specifics of how it failed, and what type of failure, is still under investigation.”