Robin May wrote in message

[about my "superfluous green arrow" question]

I can think of one traffic light where a green light means you can go
forward and turn right if no traffic is coming from the opposite
direction, but a green light *and* green arrow mean that there is a red
light for traffic coming the opposite direction so you can turn right
without needing to worry about oncoming traffic.

Yes, I know that's the case in practice: a green arrow meaning that
the opposing flow is on RED.

However, my point is that there is no legal distinction between
"solid" and "solid+arrow": the driver facing those aspects should
behave the same in both cases (i.e. assume nothing about conflicting
flows and know only that he is not compelled to stop by the signal
alone).

The presence of this superfluous combination of signals causes far too
many
people to think that they must stop UNLESS they have a filter, i.e.
that
the solid green applies only to movements that don't have a filter
even
if that filter is currently dark.

Who ever thought traffic lights can be so interesting and varied !
We've had
examples from various US States, various Canadian provinces, the two
Germanies,
Italy, France, Holland and several of those seem to conflict.

Perhaps we should allow overtaking on the left as well. The USAns seem
to manage it.

Richard [in PO7]