Don't just look at the crude-related numbers in this linked story, check out the 2014 National Movers Study map, pointing to a net exodus from North Dakota:
[srsroccoreport.com]
And now, today, this:
[money.cnn.com]

Does not necessarily, immediately, translate to laid off railroaders, if the current level of production and shipment is sustained. But nothing in this line of business seems guaranteed anymore. On second thought, if inbound shipments of drilling and pumping materials drop off, that's at least a slight hit against the rails.