I'm starting to see a train in the bus tunnel nearly every time I wait for a bus there. They aren't taking passengers yet, of course, and won't for a couple more weeks, but it's good to see them operating in close proximity with buses there. I've noticed that they are somewhat louder than buses in the tunnel, and also that some railings are probably going to be moved farther away from the platform's edge, as the trains pass very close, and I could see someone getting hurt if they lean or reach out even a little bit over the existing railings.
As I write this on the King County Metro #150, coming into downtown in the evening with a load of passengers headed to a Mariners home game, one of these trains just went by in the other direction. It makes a bell-ringing sound as it comes into and exits each station, but the ringing sound seems prerecorded -- no actual bell is being rung. It sounds a little cheesy even though it's probably more practical, and of course the sound will be good for the safety of nearby pedestrians who might not otherwise pay attention.
5 hours ago