I've been fascinated with this one, ever since the old television series. Lots of versions of the ballad exist. Casey's wife queried several of them as they tended to give reasons for Casey's absence of mind when he should have been looking out for what was in front of him. See the Grateful Dead's version for such an example.
The annotated "Casey Jones" by The Grateful Dead can be found here:
(Copy and paste the adresses into the address bar.)