Whenever a train is tied down in a siding along the mainline, a derail is always set. As you can see here, a derail does exactly what it sounds like. It is intentionally causes the train to derail. Should something fail, resulting in the train rolling without a crew, it will derail here, on the siding, before it can roll out onto the main, possibly striking another train, or derailing in a populated area.
Email Questions or Comments to the Webmaster.
