Escalators bring great convenience to people’s lives. If we take subways, shop in malls or work in high-rise offices, we can’t seem to do without them. But once escalators are poorly maintained they can turn into a threat to life.

On July 26, Xiang Liujuan, 30, from Jinzhou city, Hubei province was killed in an escalator accident while shopping with her daughter. Surveillance video footage, capturing the horrifying moment, showed that a footplate in the floor collapsed when she stepped off an ascending escalator and stepped on the plate. She pushed her child to safety the moment she fell half through,

Within seconds, Xiang was swallowed by the machinery. Preliminary investigation showed human error was to blame because mall staff had reportedly known about the loose footplate but failed to turn off the machine and warn the public of potential danger.

It was such a sad story, mingled with heart-wrenching maternal love, that many people continued asking questions on Weibo, the Chinese version of Twitter. What if the loose footplate had been reported to the maintenance agency and fixed? What if the maintenance agency had spotted small defects leading to the loose plate earlier? What if mall staff had been trained in what should be done in an emergency?

Despite the fact that many people blamed mall staff, one more important reason leading to the tragedy was the supervision and maintenance process. Firstly, there should be an effective special device under the footplate for stopping the escalator automatically when something falls into it, but when Xiang fell the device didn’t work at all. Secondly, before the accident, maintenance had just been carried out and workers forgot to screw the cover plate back into place. Thirdly, to stop the escalator quickly, one can press an emergency stop button-about 10 centimeters above the footplate - but no staff on the spot did that, hinting that the mall didn’t train its employees in using escalators safely under extreme conditions.