I think the usual way for public feeds is using hashtags (#CIEfail) rather than @messages
Example:
Train stopped at Grand Canal Dock for 20 minutes due signals #CIEfail
No buses because Harristown drivers unofficial action #CIEfail
There are a few posts already with #irishrail and #dublinbus
Here's how it works in Toronto: (#ttcu hashtag)
http://search.twitter.com/search?q=%23ttcu