Designing a Colorblind-Friendly Traffic Light

Transcript

In the past month while prepping this video, I’ve learned that people really love traffic lights… there is a huge romantic subculture dedicated to traffic lights and it’s not just people like this…

It’s also people like Tony, whose idea of a man cave is colorblind nightmare fuel. Now, for all the Tony’s out there, keep in mind I am neither a traffic engineer nor an enthusiast and am approaching this from the colorblind angle. If you think I’m out of line, throw up an amber signal and write a comment on this video.

Today on Chromaphobe, let’s take a look at one of the worst parts about driving colorblind, especially for the deutans… the traffic lights!

The last time I talked about driving colorblind on this channel, it was about whether the colorblind were actually worse drivers, or rather whether they got into more accidents. Controlled studies showed that theoretically, we should get into more accidents, but the data showed that we actually don’t, probably due to cautious adaptation, where we compensate for our condition by being instinctively safer drivers.

Even if we did get into more accidents, this wouldn’t necessarily be because we are ‘bad drivers’, but because traffic rules and technology are set up in a way that makes driving inaccessible to us. It doesn’t have to be that way though, so let’s try to design a traffic signal that doesn’t suck… or at least doesn’t disadvantage the colorblind.

SCRAP COLORS

If you don’t remember how traffic lights work, let’s ask fellow colorblind icon Mr. Rogers…

While that video is absolutely dripping in irony, that’s actually a really nice looking traffic signal though, we should adopt that…

So, first step in designing our light, let’s get rid of colors. If Einstein can drive without color, so can everyone else. Now we take the stop light, make it an octagon, cuz that just makes sense… right? Maybe put some emojis in there to really sell the meaning of each light. Make the red light a lot bigger than the others so it’s noticeable. And let’s add a sign next to each one, so you are really certain what each means. Put a spot light on that sign so you can see it at night. Have the “red” light flash at 3 Hz; the “yellow” light at 6 Hz and the green light at 5 Hz, which you can remember because the number of flashes per second is equal to the number of letters in the color that used to correspond to that light…

Dalton: “That is the worst traffic light…”

No, this is the worst traffic light… like… who green-lit this?

Mine is a close second though.

Alright, back to the drawing board, but first, let’s peek at the literature. A great paper from 1988 evaluated a bunch of different types of signals, including color, on how they perform regarding aims to be:

• Robust
• Inexpensive
• Quickly Interpretable
• Distinguishable from a distance, and
• Accessible to as many people as possible

And of all of the signalling methods the authors could imagine, color was by far the best. It scores very high in the first 4 categories, really only losing out on point number 5. signal type, beating out light order, intensity, flashing frequency, patterns, words, shapes, etc.

And despite this paper coming from Vingrys + Cole, who you may remember as the pair who tried to ban protans from commercial driving, this paper is pretty legit, and I will agree with the conclusion that we would be stupid for not sticking with color…

…but I mean, hell, why did we choose red, amber & “green” as the standard signal lights: three colors that seem like they were chosen almost intentionally to be inaccessible to the red-green colorblind of us? Why don’t we have… like… better colors? Like Amber, Indigo and Actual Green instead of cyan.

WHY RED?

Well, red was chosen as stop… for… a reason, but for what is possibly the world’s strongest cultural color association….Nobody really knows what that reason was, but there was definitely a reason. Here are some of them:

1. The road industry adopted the system of colors that came from the signal lights for trains, where they used colored lanterns to communicate since before 1850.
2. Red is a color that has intrinsically conveyed danger since at least back to the Romans, who’s red association stemmed from the red color of the planet Mars, who you may know better as his Greek pseudonym, Ares, the God of War, ergo danger.
3. Others may argue instead that we are genetically hard coded to instinctually associate red with danger, because it is the natural color of fire, blood… communism, etc.
4. Red is also the color most used by poisonous animals. Incidentally (and fittingly), yellow is the next most common warning color of poisonous animals. Likewise, if we look at berries, yellow is the most likely to be poisonous, followed by red, where about 50% are poisonous. On the other side of the spectrum, blue berries are almost always safe, and green berries are actually usually small limes.
5. Some experiments in literature show that the sudden appearance of a red light leads to a faster reaction time than other colors, though this wouldn’t have been known when the association started.
6. Maybe the most obvious solution, at least to color-normals: red has the most contrast with colors that are likely to be behind it. When driving, that would probably be blue, green, or if you live in Canada, white…
7. However, possibly the most compelling explanation is the physical one: that the red light resists Rayleigh scattering (the phenomenon that makes the sky blue) because of its longer wavelength and can therefore be seen from a greater distance.

DIFFERENT COLORS

Now, if I were to try to make up reasons why we should choose, say, indigo as stop… well, I’ve got the color blind angle and that’s about it. And would it really be so hard to change? Most stop signs were yellow from 1922 until 1954, when we just… changed them to red, and people got used to that.

And actually, people have tried to change the color of traffic lights quite a bit.  As early as 1923 during the initial rollout of traffic lights, American engineers discovered that:

“10 percent of adult males were color-blind, seeing both red and green as gray.” <McShane>

and despite that nauseating take on colorblindness we’ll give them a pass, because they also made a solid attempt at colorblind advocacy by proposing substituting red lights for blue. At the time, with only 500 traffic lights operating around the world, it would have been a good time.

However, detractors feared losing the effect of their 2 or 3 years of hard work educating drivers about the meaning of colors. They also believed that motorists would not be able to adapt, and that waffling on something as fundamental to the system as the colors could undermine the credibility of this young technology. So instead, they just tried to ban the colorblind from driving, which is an unfortunate theme on this channel.

Indeed, it would have been a good time to change the colors, because nowadays, with millions of traffic lights worldwide, good luck trying to change the colors in a system where uniformity is way more important than optimizing the system.

Further inquiries were made into changing the lights to accommodate CVD drivers in the 1960s. However, it was found that it was not possible to devise a three-colour code that can be reliably identified by all CVD types, and was only possible if they excluded protanopes. <Heath and Schmidt (1959)>.

but its not only engineers who can’t get crap done…

During China’s Cultural Revolution, the Maoists (known as the Red Guard) proposed changing the color scheme so that red would mean go, purely for the symbology. But even one of the most radical movements of modern times could not overcome the hugely ingrained attitude that red means stop.

JAPAN

But one country resisted… The land of the rising sun, refused to go with the flow… of traffic… The story here is a super interesting dive into the language of color but a bit too much of a tangent for this video, so I’ll have to save it for later. …Actually, I was just petrified of trying to pronounce Japanese words in public…

Suffice to say, the borders between colors in Japanese fall on very different areas of the colorwheel. By looking at these language distributions over the color wheel for both languages, you can at least see that they differ greatly in the cyan region between green and blue, where there is simply no one-to-one translation between the languages.

In fact, the difference between green and blue is historically not a very important one in Japanese, and that contributed to most “go” traffic lights by the 70s being a very obvious shade of blue. So I’m just saying, if Japan did win WWII… at least traffic lights woulda been way easier for people like me.

By the mid 70’s, some important international standards defined the acceptable shades of red, amber and green mathematically, so Japan could no longer blame mistranslation, and they slowly moved towards greener lights. And I mean slowly, because you can still find some token blue lights scattered around the country.

They never had a problem with the red color though. After all, there is a red traffic light emblazoned on their national flag. Christ, can you imagine if every country just had the colors of their flags as their local stop lights? Mali and Guinea wouldn’t have to change much, but crossing that border would be super confusing. The Belgians would never go anywhere, which is a good reflection of their national politics… and the Nigerians… they’d live fast and die young.

So we’re stuck with colored traffic lights and we’re stuck with the colors we have, but that doesn’t mean it can’t be supplemented with other indicators. For example, stop signs have triply redundant signals, namely the color: red; the shape: octagon; and the word STOP. So let’s go through these other 6 signal types that the earlier paper found to be so inferior to color and see if we can incorporate them as a little something something on the side.

ORDER

After color, the second type of signal is order, as in the relative position of the red/yellow/green lights to each other. Because it has been consistent pretty much all over the world since 1949, it is a critical piece of information to almost all colorblind drivers. Some colorblind people rely on the mnemonic “top is stop”, “low is go” or “RAG” for red-amber-green… and we often recite these mnemonics in our heads as we approach each intersection, which just goes to show that light position does not have the deep relationship to meaning that color can carry; since nobody has to recite the mnemonic in their head “green means go”.

So when India starts to roll out these post-modern lights where the entire pole is lit with the signal color, it leaves redditors asking, cool, but why do we still need the traditional lights then?

Well, cuz order is still super useful to us colorblind folk and traffic light order is actually one of the most successful and important standards in the world.

Which is why it’s a damn shame when some states and provinces in the US and Canada think they can pull this 5-light vertical off. Sorry Minnesota, you ain’t pulling this off. Its like when my dad thought this light switch was a good idea, and didn’t take a hint when he couldn’t find plates longer than three switches at home depot. Preserve that positional information!

Luckily, most American states are replacing those monstrosities with doghouse arrangements, and Japan hangs all supplementary lights like green arrows under the sacred triplet, both of which aim to preserve that super important positional info.

Speaking of Japan, USA and Canada, these are the only three countries that routinely use horizontal traffic lights. Horizontal traffic lights maintain the same consistent order, but interestingly, right-hand traffic countries like the US display horizontal lights as red–amber–green from left to right, and in left-hand traffic countries like Japan, the same sequence is from right to left.

Of course, any of these orders are only useful if you can actually see where the light lies on the traffic signal. At night… its pretty impossible, and that’s before the moon conspires to kill you… but there is a very obvious solution to this problem.

Most British road traffic lights are mounted vertically on a black rectangle with a white border forming a “sighting board” so the position is more clear. Recently, the UK has been moving towards retroreflective borders so the order is clearly noticeable at night.

When Kentucky implemented the same, it reduced all collisions at the upgraded lights by 15%. I found some examples streetviewing around Kentucky, and I gotta say… I was expecting more KFCs… 

And let’s not be giving Kentucky too much credit for this great implementation, because as I was streetviewing, I mainly ran into these monstrosities, because I guess the retroreflective lights were encroaching on their freedom to get into collisions.

Another concept that I’ve never seen implemented, but I discovered on some old message boards is to have the outer ring of LEDs always on for all LEDs. You get the positional info by always seeing all 3 lights at once, but only one full and 2 empty circles. I’d be very curious how this would work in real life.

Order wasn’t always so important. When electric traffic lights were introduced in 1920, each intersection would only have 2 bulbs total, which would alternate such that each bulb – when it was on – would give two green signals and two red signals. So on the main street, the top light would be red, but on the cross street, the top light would have to be green. It wasn’t until a decade later when a 12-bulb system started to take over, which allowed red to always be at the top…

The order is so consistent in fact, that when just one intersection digresses, its a huge deal. During the early years of traffic lights, one particular traffic light in Syracuse, NY suffered a string of vandalism. This traffic light, on Tipperary Hill became the target of Irish youth, who would use their slingshots to break the lights. The reason? They were offended that the “British” red was placed above the “Irish” green. Eventually, the local alderman convinced the city to install an inverted signal, with green on top, which survives to this day.

But the legacy of this thing is totally bonkers. In the 80’s, the now 70 year old vandals were ceremoniously exonerated by the major and honored as grand marshals for the St. Patrick’s Day Parade. In the 90’s, the community raised money to build a park at the intersection and erect a life-size statue to memorialize these “Brave Sons of Ireland” who “stood up to city hall” (the same city hall, which at the time was also largely Irish dominated).

And nowadays, this upside-down traffic light is a perennial icon on Etsy, where you can find t-shirts and jewelry commemorating this middle finger to the colorblind community. It just baffles my mind how some communities of American immigrants can be so nationalistic of their heritage 100 years on, yet in Ireland itself… they put red at the top of the bloody traffic light like the rest of the world.

So honestly Tipperary Hill, don’t you have something better to be proud of? Some… B-list celebrity that grew up there maybe? A highschool varsity rugby team that won state? No? Nothing? Christ, even this etsy print boldly postulates “What would Tipperary Hill be without the green-on-top light?” …Irrelevant?

Anyway, to sum up… in our traffic light design, we should also try to conserve the light order, if only to piss off Tipperary Hill. And if I have anyone colorblind watching from Syracuse, links to slingshots are in the description.

INTENSITY

Signal type #3 is intensity, such as how bright a light is.

Light intensity was actually once used as the primary signal to tell drivers to stop. Philadelphia’s police once tried to control all traffic on one street by positioning a searchlight on City Hall and blinding people when they wanted them to stop. They called it HIIT: High Intensity Interval Torching, but I’m too fat to be making exercise jokes…

Theoretically, intensity could be one way to differentiate between colored lights though, maybe making the reds brighter than the greens, which according to this old ad, decreases all accidents by 50%? Dubious… 

The problem with intensity signalling is that it’s not really a failsafe design, plus protans already perceive green as brighter than red and deutans perceive red as brighter than green, so using intensity as a signal is probably a dead end, but for the sake of protans, it should still be bright enough for the sake of noticeability.

FREQUENCY

Signal type #4 is frequency, such as how fast a light flashes.

Depending on your country, you already know the difference between solid and flashing lights. Usually, while solid red means stop and don’t proceed, flashing red means stop then proceed when safe (like a stop sign). However, I couldn’t find any examples of different frequency of flashing being used to convey information to traffic.

I think it has a use though. One of the hardest things for colorblind drivers are those damn single flashing lights that we generally have no idea if they are red or amber because there are no positional cues.

But maybe… if yellow lights flashed once per second and red lights flashed twice per second, that would be distinct enough to help the colorblind while being subtle enough to not pose a distraction. It could be a niche solution, but in any case it doesn’t make sense to incorporate that into our standard red-amber-green traffic light design.

A different kind of flashing may work though, and I don’t mean a white light flashing “S-T-O-P” in morse code. In the 90’s, The US prototyped some red traffic lights that were supplemented with a strobe effect simply to grab the attention of the driver.

As someone who has to continuously scan for red lights on the horizon, this seems like incredibly useful and anecdotal evidence shows that they are amazing, but the US has actually banned them and is phasing them out because apparently the collision data speaks otherwise. I’m skeptical… but hey, I won’t argue with the data.

SEMAPHORES

Signal type #5 is orientation, namely semaphore arms. I mentioned that the railways used colored signal lights first, but for their first 100 years, they weren’t really intense enough to work during the day, so they had redundant semaphore arms to carry the same meaning, where horizontal meant stop or caution, vertical meant go and diagonal something in between.

These arms are still in use in many train lines, but because mechanical systems are less robust than electrical systems, they have sometimes been reimagined as shaped lights, such as for trams who need to use colorless signals that cars don’t mistake as their own.

Anyway, a good general rule of thumb, is if the traffic light confuses you, it’s probably not for you and you can just ignore it… I am not a lawyer. The extrapolation of that is a 3×3 matrix of lights that can mimic these same shapes and more. The Dutch call this their “NegenOog”, which I’m only saying because my wife hates when I try to speak Dutch. NegenOog literally means 9-eye which makes sense considering there are 9 lamps, but funnily enough, absolutely do not google NegenOog trying to find pictures of this thing.

This very idea was a serious proposal for replacing colored lights in the 1920’s. Unfortunately, this idea was nipped in the bud due primarily to the cost of an intersection needing up to 36 light bulbs instead of 2 or 3. These 3×3 patterns work well with buses in high density areas where speed is very low and clarity is more important than reaction time, but these types of patterns are actually some of the worst performers when it comes to stopping quickly, so by itself, not something I’d put in my light.

PATTERN

Lets be honest though, a 9-pixel display is so 1965. Nowadays, we could have 4K traffic lights… and get them sponsored by LG! Suddenly, this opens up all the possibilities for using signal type #5, or patterns.

In 2008, a pair of engineers [Jaime Harasic and Jorge Escurra] installed their new idea for a traffic light in an intersection in Asuncion, Paraguay. The light used the standard red-amber-green colors, but because it was made of LEDs, could also make redundant patterns in the lights so red was an X and green was a vertical line.

The pilot only lasted a few weeks before the government… found out about it, realised the light had never been, like, tested, and that motorists were at no point informed that they had to pay attention to this strange light that they probably mostly thought didn’t apply to them.

I mean, thanks for trying to help the colorblind, but like… maybe test it next time. This unnamed signal then faded into obscurity, probably because they didn’t give it a cool registered trademark like the DuizendOog.

Once we have LEDs though, we can get very creative, and we all know traffic lights are a perfect target for creativity… this idea takes advantage of the LED’s ability to be finely animated to give driver’s real time meta information, which I guess, lets them know exactly how much more candy they can crush before the light turns green, plus its, like, super cool, right?

Well, this pattern not only disrupts the useful positional info that we are so accustomed to, but because this pattern changes so much, it would simply be harder for colorblind folk to spot when scanning the horizon vs. the fixed triplet silhouette that is generally so consistent. Plus damn… so expensive AND… illegal in this US.

CHINA

Not in China though, they’ve got countdown timers everywhere, some of them seem to be pretty reasonable. Others are downright terrible. This bar style light popular in Tianjin really doesn’t give deutans much chance of telling the colors apart, and these arrow lights also seem like an interesting idea for color-normals, but how is a colorblind person supposed to understand these?

Well they aren’t, because you forget that China’s solution for colorblind drivers… is to make them walk, because the colorblind Chinese cannot drive… like at ALL. China, the country that thought it was a good idea to put a sculpture of traffic lights on the side of the road, with the reasoning – and I quote –

“…the junction looked bare. They look very pretty at night but drivers should just ignore them.” <a Chongqing state spokesman>

And China… what the fuck is this?

ALPHANUMERIC

Which brings us to signal type #6, adding redundant alphanumeric signals… and by that I mean words… As you can see in these stop lights, it should be relatively easy to include words like stop and go in the lights… Words were necessary when traffic lights were young and people were first learning the color associations.

Then why’d we get rid of them? Why aren’t we using these lights to tell people to… SIGA… Well it doesn’t add much and again, just starts to obfuscate the positional information. The main problem is probably language when it comes to trying to standardize traffic lights internationally. Just look at how stop signs are treated. 

All european countries use the English STOP on their stop signs as a “universal” word, even russia and greece who use a completely different alphabet, but their drivers have learned what the word looks like, its like a symbol to them.

But if you rely on learned “symbology” of a word, why not just replace the word with a much more universal symbol? Like an X? Or a cross? Or a maple leaf? Now that looks great. After all, words are just complicated shapes that you need to be much closer to in order to interpret. Which of these lights do you think you could interpret from further away?

But all we’re really doing now is changing the shape of the light, and we can make shapes more noticeable by keeping them simple and applying them to the border of the light instead of adding a silhouette to a round light.

SHAPE

So, last but not least, are shapes, or signal type #7

We actually already use shapes as a redundant measure for traffic lights worldwide… for pedestrian traffic. These lights primarily must be shaped differently so they are not confused as signals for motorists, but the difference between a standing man and a walking man is still quite useful to a colorblind pedestrian.

But its not only the shapes that differ. Lets flash back to the chromaticity diagram defining the traffic light colors… maybe you saw this earlier… Portland Orange? Apparently all don’t walk signs in North America are neither red nor amber, but this Portland Orange in between. If you say so.

Anyway, shapes are also already used to indicate motorist direction in the form of arrows when necessary, and we’ve already established that some regions ONLY use green lights shaped like arrows, so let’s look into putting them in our light.

In the late 90s, Texas tried out the Unlight system, which made green circles, yellow triangles and red octagons, which is a tempting choice, but a bad one… even in THIS picture, I first saw a circle because the shapes are too damn similar. It also used some of the first LED traffic lamps, which I guess made the designers a little overconfident to the point that they thought they could just scrap order again.

So UniLight sucks, what about UniSignal, from 2009? Much better, subtle concept, but despite intending the UniSignal to be ‘UNIversal’, they were useless for all but the simplest intersections, as they had no solution for handling protected lefts.

Plus, I found the shapes quite counterintuitive. Maybe it would make sense for the triangle to be treated like a forward arrow and applied to green, or even to be associated with a yield sign or caution sign and applied to yellow.

How does ColorADD fare? It starts off getting lucky with their yellow light that resembles a diagonal semaphore, which is a perfect symbology. But then their red light is like… a forward arrow kinda? We can obviously do better than ColorADD.

So lets fast forward to a good implementation. By far the most extensive rollout of shaped traffic lights in history was in Eastern Canada. They used to be ubiquitous in the 90’s, but the Quebec ministry of transportation phased the shapes out because they were found to be… redundant. Like yeh… that’s the point.

Nowadays, I was only able to find the lights in Sherbrooke and the mini province of Prince Edward Island, but they are all over and they are beautiful. So lets break it down:

• Reds are squares, greens are circles, and yellows are diamonds. Good for the symbolism and good to differentiate.
• They’re always horizontal
• The reds are larger and there are always two which makes them brighter
• They are positioned on the outsides of the light so you don’t have to remember left or right and the two separated lights make it even more obvious that it is red.

In its simple 4-light form, it’s brilliant. Of course, you need to account for turn arrows, which they do with 5 and even 6 lights in a row. I would rather see them adopt the hanging protected left utilized in japan to protect that quadruplet, plus add a retro reflective border utilized in other regions,

But otherwise… this is it, this is pretty much the best traffic light I can imagine. It takes color, shape, position, pattern and intensity signals into account and according to the one colorblind Prince Edward Isländer I spoke to, they are as great in practice as I imagined they were in theory.

COMPUTERS

Anyway, I’m not one to dwell on a good thing, so let’s look at some completely different solutions. Instead of changing millions of traffic lights, what may be easier is to just give assistive devices to the colorblind.

In 40 of 50 states, even achromats are allowed to drive, and they have no color vision, reduced visual acuity and general day blindness. All they need though are some special binoculars, red lenses and enough training on how to use them.

Even better, a patent from 2005 basically uses a digital camera on your car to detect traffic lights, amplify them to a display in the car, and “correct” for your specific type of colorblindness so you can determine the traffic signal’s color.

And the patent is right that computers are the future, but clings on to the whole “lets help the colorblind see color” fallacy, when really we can just circumvent color completely. Actually, we’ll circumvent the colorblind too, when autonomous vehicles finally popularize but they won’t be using color either, they’ll receive the traffic signal in non-visual means… i.e. 5G…

And clearly regardless of the prevalence of self driving cars, there will always be the stubborn few who want to drive themselves. But in my utopian future, they will not need traffic lights. Instead, their car will receive the same 5G signal from the network, then the car can convert that to any kind of perceptible signal directly to the driver, be it audible, visual, tactile or olfactory.

*sniff* smells like a red light…

That way, a driver can calibrate their signaling system to work for their specific condition or preference… and cyclists can get bent.

ROUNDABOUTS

That all kinda seems like a copout though, right. Saying “in the future, we’ll evolve past stop lights!”, but some countries have actually already evolved to live without stop lights.

For example, look at North Korea, which for generations has put off adopting colored signal lights in favour of providing jobs to the comeliest of their lasses. If you look at this recent photo from Pyongyang, you may think “oh look, that new green traffic light is going to take ‘er job!” or you may notice “there are no cars in this picture! Just 23 people waiting for a bus!” Oh North Korea… never change.

Okay, for a better example. Where I’m from – North America – a one-stoplight-town is a disparaging moniker for a small town of only a few hundred people, but where I live now – in Switzerland – my town of 17000 people has precisely zero stoplights… mainly because since 1987, Switzerland has been transitioning from traffic signals to roundabouts.

And if you look at any comparison of roundabouts vs. traffic signals, the circles win out for most types of intersections, improving on lights in:

The comparison itself is covered exhaustively in other youtube videos, but most important for this video… roundabouts are completely accessible to color blind drivers.

• Safety – fewer collisions, fewer injuries, fewer deaths
• Flow – more cars through per hour, each car gets through faster
• Cost – no maintenance involved and far lower risk of failure

What I want to emphasize here, is when you are challenged to redesign a product to be more accessible to the colorblind, then you automatically pigeon-hole yourself into a very small subset of solutions. Just like I discussed in my ColorADD video, the question should generally not be “how can we help color people see color here?” but rather “what is an overall better solution for everybody?” and in most cases, it will ALSO end up being accessible to the colorblind.

This is chromaphobe.