Unlike a lost network packet a single derailed car can slow down the whole train and any trains behind it on either side. By using longer trains they are puttin

Unlike a lost network packet a single derailed car can slow down the whole train and any trains behind it on either side. By using longer trains they are putting more eggs in one basket. On top of that longer periods of stress on a particular part of rail due to the longer trains is probably uncovering new failures in problem spots especially if heating is involved in the problem. Longer train = more time for a piece of rail to heat up. I think the metric of concern would be total consecutive time the rail is loaded or something like that.