Wonder if Japan, with the signals running protected-only phasing, if they run any kind of lead-lag phasing at all, and/or if they have any kind of yellow trap issues there?
In the video, it appears that their PPRT signals run the permissive phase first (yield on circular green), then run lag-lag operation before running phasing on the cross street. Not sure if Japan uses any kind of leading lefts at all with PPRT and/or if their signals are pre-timed (no gap-out if an approach is out of vehicles)...
From what I can tell from the videos I've seen, signals seem pre-timed and not based on any sort of actuation, apart from by pedestrians at certain intersections (from research, "automatic walk" seems to be the norm).
To us, this seems really ass-backwards, especially for a tech-forward country like Japan. But they do have a few differences from us. First, the vast majority of right turns (across traffic) are permissive, even those with two or three lanes, and it seems assumed that, at these intersections, the solid green cycle will allow most traffic to turn. So, the green arrow, which again is at the end pretty much everywhere I've seen, is relatively short. So most intersections effectively operate with two phases, with a short green arrow at the end
if necessary -- many junctions are fully permissive. Second, many areas have lots of pedestrians, so vehicle-actuated signals would get very annoying for pedestrians, so pre-timed signals seem to be preferred as a result.
All this said, I would really love to visit Japan and see for myself more about how everything works because these are all just my guesses from what I can see in videos and on Street View.