Source? I would have figured that a moose didn't have enough mass.
But I also know how big a train is, and I still don't see it. I know that in terms of mass, a train is to a car as a car is to an empty beer can. A car can derail a train, but won't very often. A moose might weigh as much as a small car, but has less stiff metal in the frame. It still might derail a train... but not very often.
Still waiting for some evidence for the claim that "moose are responsible for quite a few train derailments".
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[1] Yes, I know that not all railroad engines have them. Most that don't have a flat plate that still gets down pretty close to the track.
I'm just spreading moosinformation