There has now been a third train explosion carrying oil from North Dakota. The first was obviously in Lac Megantic in July 2013, where a Montreal Maine and Atlantic train exploded in a fireball, killing 47 people. In November it was rural Alabama. In December a BNSF train accident led to another fireball and the evacuation of 3400 people in Casselton North Dakota.

Regulators are now saying that Bakken crude is more flammable, and the trains carrying it, and other hazardous materials, are increasingly in their focus. 

Of course the larger issue is fraught with complex issues and multiple sides, from economic to environmental to societal, and is pitting the oil producing industry against the "oil reducing industry." And while it may be a boon for railroads and pipelines, at some level it still comes down to numbers.

Increasingly the oil is coming from non-conventional locations, and therefore being delivered in "new" ways.  If trains were 99.9% safe before these accidents, then you'd expect one accident for every 1000 trains. If you take the number of "unit oil trains" (a train of 100 oil cars) and make them go from very few (and therfore very few accidents) to perhaps 10/week from 10 locations in North America, you might get 5000 trains per year, and five accidents per year. (Does it seem like 'we're right on schedule?")

The analytics aren't complex - the risk is multiplying.  Getting from 99.9% safe to 99.99% safe is hard and expensive. The regulators, the rail companies and the oil companies have hard choices ahead of them.