Common Sense wrote:

It’s a lot riskier to move oil by train instead of pipeline

http://www.washingtonpost.com/blogs/wonkblog/wp/2015/02/20/its-a-lot-riskier-to-move-oil-by-train-instead-of-pipeline/

So it's pretty clear here that moving oil by pipe is a less risky proposition than moving it by rail. Both the rate of accidents and the total amount of spillage varies less for pipe transport than for rail transport. To the extent that we can shift some of that transportation burden from rails to pipes, we can drastically lower the odds of spill incidents, and potentially lower the overall volume of oil spilled as well.

That's kind of a no-brainer isn't it?

But, can I ask, how much more oil is spilled by pipeline than by rail if there's an accident?