Thanks to John Ewing for sharing this with us. He notes, "The long-dead designers of the steam locomotive involved included a key safety feature, and it worked, many years later. The accumulation of deferred maintenance items, each non-critical by itself, ultimately led to a catastrophic failure. The loss of a culture of knowledge about an exacting but economically obsolete technology added risks poorly appreciated by those still using the technology. The challenges faced by a small family-owned company in operating a steam locomotive without the old infrastructure in place are daunting. I am not in the heating trade myself; I work in the technical side of the rail industry -- but not with steam locomotives!"