If you could add a new color to the traffic light?

[Zmapper]

Ok, so I was looking at some old drawing's from when I was 5 or 6 and noticed I didn't try adding new colors to the standard signal like every other young roadgeek did.   So my question is; what color would you add to the traffic signal? Personally, I would add blue as a way of letting emergency vehicles and trains know that the intersection was pre-empted properly.

This is just for fun to see what color everyone would add.

[Duke87]

I added blue and purple. Why blue and purple? Well, there was this board of plastic peg-things that I used to play with, and the pegs were red, yellow, green, blue, and purple. Naturally, I used the first three to make traffic lights. Adding the others seemed only logical.

My invented uses for them were rather boring and pointless, though: the blue light would come on if the next light down the road was in flash mode rather than functioning as a full signal, and the purple light would come on if the next light down the road was out completely (power failure).

[US71]

I added blue and purple. Why blue and purple? Well, there was this board of plastic peg-things that I used to play with, and the pegs were red, yellow, green, blue, and purple. Naturally, I used the first three to make traffic lights.

The way some people drive, you'd think they were waiting for a purple signal 

[Ian]

Flashing purple: for the E-ZPass (or hey, any electronic tolling) lanes at a toll plaza.

[froggie]

I wouldn't.  Drivers are confused enough just with 3 colors...

[J N Winkler]

You could try white:  in Austria it is used to denote the movement controlled by a particular indication, and in Germany it is used for "Signal kommt" (signal comes) on pedestrian signals which are not in 24-hour operation (in this respect it is similar to "Appel enregistré" in France or "WAIT" in the United Kingdom, both of which are shown on the side controls rather than the signals themselves).

[english si]

white is used in quite a lot of places for tram signals (and special signals for buses) http://en.wikipedia.org/wiki/Traffic_light#Lights_for_public_transport

The UK (well the few areas that have trams) uses a white line - vertical allowing the tram to go, horizontal telling the tram to stop.

[oscar]

I wouldn't.  Drivers are confused enough just with 3 colors...

Agreed.  Don't forget the color-blind, who depend on traffic lights having only three colors, in standard red-yellow-green order.  Adding a fourth light, in a color they might be unable to make out, would just throw them off, at least until traffic lights nation- (or North America-)wide are fully transitioned to the new setup.

If you want to modify lights to convey additional info, different shapes (such as the standard arrows), or flashing rather than steady lights, seems better than adding colors.

[Brandon]

White is already used for emergency vehicles around here.  It is an auxiliary to the signal and usually only has one of these lights per direction.  The light is off most times, but flashes for the street that the emergency vehicle is on (in conjunction with a green signal), and is steady for the cross street (in conjunction with a red signal).

[Alps]

I'd support the purple electronic toll light.  The purple can be made sufficiently blue to be distinguishable from red by those who are partial color blind.  Also, red is always on the left on horizontal assemblies (or on top for vertical), so purple can just occupy the other position for those who are full color blind.  I would want to know if color blind people can see a bluish purple as distinct from the existing green color before allowing them both in the same assembly.

[aswnl]

Traffic light in Antwerp, Belgium.

Guess the colors... 




And no, it's not a photoshop...

[Duke87]

Red ball, yellow ball, green ball, yellow arrow, green arrow?

[Zmapper]

Duke87, I don't think that Europe uses the common tower layout that you are familiar with.

[aswnl]

Well, in Europe usually traffic lights only have 3 lights in height.
Green arrows are placed horizontally. Not in Belgium however.
This Antwerp traffic light has red / yellow / green / green left arrow / green right arrow placed just under each other.