The initial fire between Nantes and Lac-Mégantic that was put out before the train rolled away and caused a far worse fire might have been sabotage. But the reasons this became such a huge disaster really looks like incompetence.
Time line:
http://www.edmontonjournal.com/news/M%C3%A9gantic+fire+timeline/8626739/story.html
Or by diesign
I have read other articles about this disaster with a number of knowledgeable or thoughtful comments. Some seem to think that environmentalists against exploitation of tar sands deposits might of done something. A number of others suspect that oil or Canadian government interests may have been responsible because they want the XL Pipeline approved. No one seems to pay any attention to the fact that a major tar sands oil spill in an Enbridge pipeline in 2010 into a tributary of the Kalamazoo River has already cost a $billion in cleanup and is not finished yet. Dozens have permanently lost their homes because of the environmental toxicity caused by this disaster. Lots more at Google.
Both forms of transport have their problems. Tar sands oil slurry is for more toxic, acidic and abrasive than regular oil and the percentage of ruptures is much higher. It is also extremely difficult to remove from water ways in case of spills. The oil in this tanker accident was carried in single hull tankers which puncture easily in accidents. Double hulls and much better pipeline procedures need to be in effect. Apparently pipeline fires are not unknown either.
Bottom line, 72 tankers containing fuel with enough fire and explosive power to equal several Hiroshima bombs was parked overnight with NO watchman or guards with cell phones in our current era of terrorist danger. Gross criminal negligence. We must have stronger safety laws and criminal sanctions.