Horizonatal vs. vertical traffic lights

When I was a young whippersnapper back in the 70s living in Seattle, I recall there was an initiative to convert all the traffic lights at city intersections from vertical to horizontal. IIRC, it was determined that horizontal traffic lights were much better for colorblind people. Over the next couple years many of the lights were converted, then inexplicably and without any explanation they all became vertical again.

Anyhow, I was reminded of this when I saw a few horizontal traffic lights in the city where I live now. Being just a lad at the time, I just assumed there was a darn good reason why colorblind people needed these horizontal traffic lights, but today, for the life of me I can’t imagine why that would be the case! Can’t colorblind people identify which lamp is lit at least? And if the light was horizontal wouldn’t there be a possible confusion whether the green was on the right or the left side?

Ok, so, does ANYONE recall this? Was this just a case of an insane city government? Or am I insane and making up my own memories (not the first time!) ?

And BTW, since I still see a few of them from time to time, why ARE there horizontal traffic lights?

Hmmm… Dunno if the reason why they are horizontal or vertical has got anything to do with colourblindness. I live in Holland and here, we’ve have both sorts, even though there are more vertical ones than horizontal ones. (Same situation in Montreal, Quebec, Canada). I think the horizontal ones are found at (very) intricate or busy crossroads / street-corners where vertical lights could be confusing or would hardly be visible.

Btw, does anyone know if there are any round-abouts in the US? They’re pretty nice alternatives to traffic lights for not-too-busy corners (more economical, among other things).

Round-a-bouts are supposed to be the better option when there is similar traffic flow from all entrances to the intersection. Traffic lights are preffered where the traffic flow is one sided, eg a main street with high flow and a minor street with low flow.

In Darwin the lights are all vertical, I have never seen horizontal lights.

I have seen the occassionl “round-about” here in the US, but they’re so rare I can’t for the life of me remember what they’re called (not “round-abouts”)

Anyhow, regarding the OP, when I got to the line about “horizontal being better for colorblind people” my first reaction was no way. When the lights are vertical it’s always red on top, green on the bottom, so even if you can’t see the color you can still see which is lit. If confronted with a horizontal light… well, quick, is green on the left or right? C’mon, c’mon - you’re doing 50 and you have to decide now!

They are supposed to make the green lens in traffic lights a shade of green that looks blue to at least a large portion of the color impaired, but from experience I can tell you that this isn’t always the case. Which can make driving at night even more exciting than usual, and at which point the position of the light becomes extremely important.

Roundabouts are called “traffic circles” or “rotaries” in the U.S. There are quite a lot of them here in New England. Most people from other parts of the country–and some from this part–hate to drive in them, so few new ones are being built. (I’m used to them by now, so they don’t bother me any more). The newest ones I know of were built in the 1960s, I think. I thought it was in a column by Cecil that I read they were a lot more popular before traffic lights became common, but if such a column exists, I can’t find it now.

I’m red/green colour blind, the vertical traffic lights work fine for me.
Actually I don’t usually have a problem seeing what colour is lit, but sometimes when there is a lot of sun they look pretty alike (not sure thats even a problem caused by colourblindness), but I’m just as able to tell what is up and down as what is left and right.

Just to add I think there is a difference between the 2. IIRC one has traffic light controls and the other doesn’t? - I don’t remember which one though.

<<IIRC, it was determined that horizontal traffic lights were much better for colorblind people. >>

Are you sure that you don’t mean VERTICAL (red on top, green on bottom) lights work better for color-blind people? That is what I’ve always heard.

And as a mostly night-blind person, while I can see the light itself at night (and am blessed with the ability to tell red from green) I couldn’t tell you at any significant distance from the intersection whether it was the top light or bottom light that was lit. I simply can’t see the traffic light case in the dark.

The reasonable explanation to me would be that in the daytime, when you can see the full set of lights, it IS easier to tell “stop” from “go” when they are up and down, not right and left. Many people DO confuse right and left, or east and west, or lateral directions, but I’ve never heard of anyone confusing up and down yet (except, of course, for the Latinate terms ‘horizontal’ and ‘vertical’…but hardly anyone swaps those. :wink: )

Of course, since they started making green-arrow lights (the kind where the lens is painted dark to show only an illuminated arrow, turning left, going straight, or whatever motion is permitted) I’ve often considered that it would make more sense to simply paint the traffic light lenses with some kind of symbol. For GO (green) you would have a vertical line or a dark, upward pointing arrow; for STOP (red) you would have an X or anything else unmistakable for the GO sign. Even if you can’t see the colors, or the sides the light is on, you can see the darkened symbol in the light.


Because most traffic lights are positioned vertically, that’s how people see them when they’re beginning to drive, whether they’re colorblind or not. My dad’s colorblind, and he assumes the top light is red, and the bottom one is green. If he comes across a horizontal one, he’s not sure which end is which, because the light theoretically could have been rotated in either direction. So he basically has just memorized their position, and if the light does happen to be horizontal (rare around him, I think), he asks someone else in the car or else proceeds very cautiously (or does whatever the car in front does).

Colorblind people do not normally have trouble discerning which light is lit, just as noncolorblind people don’t. (I would think that if they don’t, it because of an additional visual problem not related to their colorblindness.

Back to my OP, I just spoke with my mother about the horizontal traffic lights, for it was her who told me way back when about their being superior to vertical lights for colorblind people. And yes she still remembers when they converted the lights in Seattle and she never recalls anyone she knew questioning the theory about colorblind people. The City said it was so, so she believed them. Hmm, based on the responses in this thread so far I’m wondering how could people have been so naive back then?

What about the people in Australia?

On Long Island, horizontal traffic lights are definitely used for special purposes only, usually found where there’s an intersection right after a bridge, and vertical lights would be partially obscured by the bridge (also in places where there is tight vertical clearances, such as parking garage entrances).
Otherwise they are extremely rare, partly because people don’t remember the normal ordering of red/green for a horizontal light.

In one of David Feldman’s books (such as Do Penguins Have Knees? maybe), he says that traffic lights are now all vertical to help colorblind people, because they can always count on red being on top.

The trouble is, the lights that I see everyday (around north Dallas) are almost all horizontally oriented. I can’t recall seeing any intersections that have vertical lights. Do they still make those?

Two additional reasons to mount traffic lights horizontally:[ul]
[li]Clearance – a horizontal light doesn’t hang down as far, so they’re less likely to be hit by tall vehicles.[/li][li]Wind – vertical lights often hang down off a wire, allowing them to swing in the wind. Horizontal lights are usually attached at both ends, greatly curtailing their motion.[/li][/ul]