When it comes to the question of how best to transport oil, environmentalists tend to act like rabbis being asked for advice on how best to roast a pig: The thing should not be done in the first place. So opposition to Keystone XL becomes an assertion of virtue, indifferent to such lesser considerations as efficiency (or succulence).

But the pig will be roasted. The oil will be pumped. What happens then?

Like water, business has a way of tracing a course of least resistance. Pipelines are a hyper-regulated industry but rail transport isn’t, so that’s how we now move oil. As the Wall Street Journal’s Tom Fowler reported in March, in 2008 the U.S. rail system moved 9,500 carloads of oil. In 2012, the figure surged to 233,811. During the same period, the total number of spills went from eight to 69. In March, a derailed train spilled 714 barrels of oil in western Minnesota.

Predictable, you would think. And ameliorable: Pipelines account for about half as much spillage as railways on a gallon-per-mile basis. Pipelines also tend not to go straight through exposed population centers like Lac-Mégantic. Nobody suggests that pipelines are perfectly reliable or safe, but what is? To think is to weigh alternatives. The habit of too many environmentalists is to evade them.