Thanks for taking the trouble to point out the lack of information we provided in our alert. I think if you look at it again you will see that we DO link to their website which does explain the event and where it affects our service.
But to make it more clear right up front, I put a couple of paragraphs that explain what the event is and also put a link to the PDF of their map on our alert.
I hope this answers all your questions.
TriMet WebmasterEpic, aye? I've already made a difference! Yay!