The 501 is the first run of the day out of Seattle (https://www.amtrak.com/content/dam/...imetables/Amtrak-Cascades-Schedule-121817.pdf), at 6 a.m. Previously, the 501 left at 7:25 (https://www.amtrak.com/content/dam/...imetables/Amtrak-Cascades-Schedule-022016.pdf). The 6 a.m. departure time for the 501 was brand new as of Monday morning. It's reasonable to guess that a) it would be train-folk who would want to be on the inaugural run on the revised route, and b) fewer people might be on this new and earlier run. It's not proof-positive, but not an unreasonable premise.