Claims about how dangerous the pipeline would be are a bit baffling. The train accidents involving the transportation of oil that occur with some frequency are absolutely horrifying, and in many cases these routes bring massive volumes of oil through major cities, within throwing distance of schools, parks, apartments, etc. It is not obvious why a pipeline over the Great Plains poses a less acceptable risk.
The assumption is not that there is a fixed pool of oil to be shipped either by rail or by pipeline, but that by building the pipeline, a larger amount of oil will become economical to extract or ship. "Making the pie higher," as it were.
