Time to spare a thought for an Australian train driver who is remaining anonymous. He (or she, we don’t know) stepped down from the cab to investigate something that didn’t seem quite right. All well and good and nothing out of the ordinary until physics and specifically gravity intervened. A massive object like the earth exerts a considerable gravitational force to objects near it. Objects like, for example, a train stopped on a very slight incline with no means to prevent movement. Our driver looked up to see his train heading off without him and towards a place nearer the centre of the earth than that in which he left it. Trundling off downhill on its own in other words. It began oh so slowly. A train has however very low rolling resistance so once it gets going it’s going to keep right on going so long as even a negligible gradient is available. Off it went then.
In an ideal world our hero would arrive in a helicopter and abseil down to a locomotive, scramble in and apply the brakes just in the nick of time to avert terrible disaster.
In the real world somebody sitting in an office 1,500 km away in Perth pressed a few buttons which moved a set of points and derailed the runaway without injuries but with an impressive amount of repairs to be done to track and rolling stock.
It hasn’t yet been revealed what happened but I’m guessing the driver is going to face one of those meetings where tea and biscuits are not supplied.