He sees his children jumpin’ off
At stations one by one
His woman and his best friend
In bed and having fun
So he's crawling down the corridor
On his hands and knees
Old Charlie stole the handle
And the train it won't stop going
No way to slow down
Charlie's children jumpin' off is an interesting metaphor, likening parenthood to being a train that your children rely on and depend until they grow up and metaphorically jump off the train at different stations throughout the "journey of life".
As can happen when all the children leave home, a marriage can fall apart, and Anderson paints a picture of adultery committed by Charlie's wife with his best friend.
Yet life goes on and the metaphorical train that represents Charlie's life carries on towards its inevitable end.