So very sad.
I was reading that the media contacted Gerstlauer around 4pm (they're the German mega costar giant who designed and built Smiler) but the company had, at that time, not been informed of the accident.
I am an absolute coaster fiend. I think like many earlier posters said, you do really just take safety for "granted" at a tussauds/merlin theme park.
I've riden the smiler about 15 times.
My brain is remembering a time where on that coaster We were "held" at the bottom of the second winch system because the coaster before us on the section we were about to ride hadn't come in. (that ride has 2 "halves" winch up and ride, then winch up and ride) it has sensors galore telling me that sending off a coaster when the track isn't clear must be very difficult. Either the reset of the system immediately before the accident (it was suffering "technical difficulties") affected the monitoring/sensors which is supposed to ensure that the operators can't make those mistakes or it really was gross negligence and someone overrode... But I just can't believe that's possible.
I feel desperately sorry for all of those involved and I hope that the injuries are being up played by the media.