I was driving on East Burnside tonight when I saw a MAX train ahead of me with a peculiar blue light in the rear window. Turns out it was a set of new Green Line cars, they must be running tests during off-peak hours. The cars are really modern and streamlined looking, much more visually appealing than the current models.
Yes, the Type IVs (400 series) are undergoing nighttime testing.
http://www.trimet.org/max/newtrains.htm
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