I think because it was pretty last-minute they didn't have a detour ready. I dont think they could run superliners up the NEC due to tunnels, and getting a last-minute detour via CSX or NS seems hard to achieve (I think when service disruptions like this happen, cancelations are far more frequent than a detour).The Harpers Ferry bridges were on fire for a time today. That canceled 29 and 30.
But why not just run 30 to Pittsburgh and then let the people take 42, or better yet, run 30 through Harrisburg?
29 could have gone up to Philadelphia and turned left to Harrisburg. So why doesn't Amtrak have some sort of detour plan when bad things happen?
jb