A railway-safety engineer met in Melbourne described audible warning detonators placed many kilometers ahead of the approaching train. A train running over one would set it off and alert the driver to begin braking. The mining trains involved carried masses compared with cruisers and capital ships. Those heavy loads explain the long distance allowed for braking.
Notable Point · 2:25:58-2:27:19
Why mining trains need warnings kilometers ahead
A railway-safety recollection connects the mass of Australian mining trains with warning distances measured in kilometers.