Conversation

"the next train will be an additional train and boarding will be easier"

I mused a year or more over the phrasing "this train is an additional train" and what it means. Why would I care about which trains are regular or additional?

But the message here provides a tiny bit more context and a hint, and the empty train confirmed my interpretation: What's relevant is that this train originates at this station rather than coming all the way from the end of the line, so it's empty instead of being already full.