To follow up briefly on that, when you get to below -25°C, it's not a question so much of preparation as it is of physics. Metal becomes brittle. You're at risk of derailments. Rubber hoses crack and leak. You have to operate more slowly in order to operate safely. That's just one of the conditions. It's like driving more slowly on the highway during a snowstorm. It's a safety consideration.
On March 19th, 2018. See this statement in context.