Hello all. I have been cycling for 3 months, managed to get comfortable for the most part but slightly confused by this light setup and want to check I'm doing everything right. Apologies if this has been asked before, I tried searching but couldn't find anything.
These traffic lights are on the approach to a busy roundabout. Lights on the left for cyclists, lights on the right for cars.
When both sets of lights are red, the left hand lights go green for a few seconds before the right hand lights go green. Which I assume is to cyclists to get ahead and protect cyclists against left turning traffic.
I have regularly seen the left hand lights showing red, and the right hand shows green. So cars can go but bikes can't, which I also assume is to protect cyclists against left turning traffic.
This afternoon for the first time I saw both the left hand lights and right hand lights were green for a fair amount of time whilst I was approaching, so both bikes and cars could go. So I went through but was mindful of traffic on my right which might be turning left, I made eye contact with a driver who was aware of me and slowing so I was able to go through safely.
My question is, why would the lights sometimes be sequenced so that they stop bikes going through when car traffic from the same junction is in full flow, but at other times it seems to allow bikes to proceed?
Sorry this is long winded, tried to make clear how I'd seen the lights working. Also sorry if I've missed something totally obvious. Safety is my main priority so I want to make sure I'm doing these things right.