TriMet quietly added on-board microphones on its 55 new buses.
Unlike previous bus models, the 3000s have multiple microphones constantly recording everything from rider conversations to strange mechanical noises, just in case the audio needs to be used in crash and criminal investigations.
In older buses, drivers can hit a button to activate a single microphone positioned at the front in emergencies. They don't always use it.
Read more at OregonLive.com.