On Friday the Ninth of June in the present year, Mr. and Mrs. Boffin (in their manuscript dress of receiving Mr. and Mrs. Lammle at breakfast) were on the South-Eastern Railway with me, in a terribly destructive accident. When I had done what I could to help others, I climbed back into my carriage—nearly turned over a viaduct, and caught aslant upon the turn—to extricate the worthy couple. They were much soiled, but otherwise unhurt. [...] I remember with devout thankfulness that I can never be much nearer parting company with my readers for ever than I was then, until there shall be written against my life, the two words with which I have this day closed this book:—THE END.Of course, I just came across this on the internet because I'm still in the early chapters of Our Mutual Friend.
Charles Dickens, postscript Our Mutual Friend
However, thanks to my interest in weird fiction I have heard the story many times of Dickens' close brush with death in that railway accident. It is often told when reading or referring to Dicken's short story The Signalman, which was a favorite of H.P. Lovecraft and makes it into many weird fiction and ghost story collections. It directly shows the effects of that accident upon Dickens' writing.
Many people on the train were killed or injured so we are not only lucky the manuscript was unhurt but that Dickens was able to finish the book. Perhaps that is why he sent every chapter of Edwin Drood directly to the publisher as soon as he finished it. It didn't stop the book from being only half finished upon Dickens' death, but I can imagine the relief it was to him that someone was keeping it safe as he progressed.