We had a derailment of the DM&E (Better known as Derailments Made Easy) near me yesterday. Preliminary reports state that it was a bridge abutment that gave out. CP is denying that at the moment, but I would be willing to bet that is what happened.
This line, known as the “Cowboy Line” has not been rebuilt since the 50s by the C&NW. DM&E did replace all the 50 lb rail with 100 lb rail about 5 years ago. They did this to handle the increased bentonite clay traffic. The problem is they never reinforced the bridges. These are wood pylon bridge designs that have been subjected to South Dakota Weather for over 50 years. They increased the size of the rail cars running on the line, as well as the size of the trains. Most trains coming out of Belle Fourche are in the range of 75 - 100 cars.
It was a matter of time before something happened. Thankfully no one was hurt.