Do they operate the same sequence that usually on approach to a green and filter light lights a likely to quickly change to red so slow down. I know the right side filter light unsure about the left side filter light with green on.
Usually the filter comes on then the red goes to red/amber then green then both the filter and green light go back to amber at the same time.
I think
Sequence and timing depend on the junction, they will have been timed after observation, mostly to cause as much mayhem delay and congestion as possible 
Many modern traffic light installations don’t have a fixed sequence. They respond to traffic volumes and adjust themselves accordingly. The A5/A45 crossroads at Weedon is a good example that many will have seen when the M1 is closed between J16 and J18 - the sequencing of the lights (and the right turn filters) changes completely in response to traffic flows.
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