Come on, Xplorer2000, read the posts already made. Tom Nelligan has already said the date was August 21, 1969, and said it was reported in the November 1969 issue of TRAINS. What more do you want? Or are you saying there were two separate incidents? Merry Christmas anyway, LOL!
Now while we're at it, I recently saw an old RAILROAD magazine from the 1940's which had a report of some boxcars being shoved off the end of a track and across a street - that might have been Chicago but I can't be sure. There is a book called THE SNOWFLAKER about a guy working the NYC in Rochester NY in the 1940s and they did the same thing there - shoved a track out into a road, and didn't know it until a trolley motorman came asking how long until they pulled the cars back!
That's got to be one bad feeling, when you realize something ran away or was shoved too far, and it's pretty obvious you're not going to be able to cover it up.