In recent years, Transport Canada has, in several rounds, strengthened the rules on the securement of unattended trains. Offhand I don't have the statistics on unattended trains and dangerous goods, but a train can be unattended for some period of time in the course of a journey.
As an example, I can give you the latest strengthening of the rules after the terrible tragedy with a grain train in Field, B.C. Transport Canada imposed very strict rules for the securement of trains on mountain grades. That train was unattended, but it was unattended for literally a few minutes while the crews swapped. Because one crew had reached its time limit for fatigue, they were swapping to a new crew, and in that process something happened and the train started to roll. In response to that, we put in place a requirement for hand brakes even if the train is stopping for a just a minute on a grade.