maveri wrote:but i think it will be beter to change "two yellows" with this "one yellow"
green, one yellow, two yellows, red, green...
or maybe it's real law (:
The railroads here uses this system:
red - stop
1 green - drive
2 green - drive and you are sure that the next signal will show green once you reach it (but not the number of green lights).
on top of that yellow can be used. It means slow down, so if the signal got a yellow light, it will not just show red, but yellow and red (slow down to 0). Green+yellow is allowed to go, but at reduced speed (the signal will then got a subsignal below it telling the speed, either display or a sign).
One yellow is never lid on it's on and two yellow lights is a special signal indicates stop unless the train computer says otherwise (based on the signals it gets from the tracks). The idea here is that it can be used when the train in front of it is say 500 meters away, but there aren't any signals in between. The train can then be allowed to go say 400 meters at reduced speed. This is very useful during rush hour, but it needs constant updating from the tracks.
If we are to use this system, we should do it like:
2 greens - 1 green - red - 2 greens
It gives one less signal display compared to the screenshot, but it's based on real life signals.