On May 28, 2016, at 12:15, BPJ <[log in to unmask]> wrote:

> Den 2016-05-28 kl. 09:30, skrev R A Brown:
>>> in most countries there is a lot of blue in the green
>>> traffic light so that people with red--green color
>>> blindness can distinguish it from the red light.
>> Interesting - I had always assumed such people made use of position of the lights

> So did I, 

Some traffic lights in the US (and I believe in Canada) are horizontal. Not much help if you don't already know which end is which!

> but then one time I traveled in the dark, where the relative positions weren't visible, with a color blind driver and just had to ask! :-)

Good thing you weren't driving up Tipperary Hill in the dark (in Syracuse NY)! That one's green over red!

> /bpj