In several of his books Heinlein writes as if a known incident, about a woman out for a walk with her husband whose foot is trapped in a railroad bed, and an unknown man who tries to help. All 3 die, but the two men, even the one who doesn't know her, never stop trying to free her.

Does this have a basis in fact?

The Kansas City Star from 1880 to 1941 is digitized and searchable online, and I've never been able to locate a newspaper account of the incident.

This has been discussed before. Heinlein vividly recalled this incident from his childhood - and I always assumed it happened in Kansas City. I choose to believe it is a real story.

I've thrown the query out on a more general forum good at collectively answering questions. No one has come up with anything, and quite a few, writing without RAHawe, note that it is very parable-ic.

I am wondering if it is a story he heard, maybe even a sermon or some such, and either retained it as factual or decided to present it that way.

Excellent find, Bill.

It's likely that there were many rail-related deaths in those days and many may have loosely fitted the story Heinlein later told. One possibility was that we would never find a specific instance even though the gist would have been true.

This one would have been when he was about 12 and would have made an impression. It's possible he heard it second or third hand, with the details (such as about the third figure) blurred.

I concur. First-class research.