Improving the Readability of Public Transport Maps for Colorblind Travelers

Report Cover

A group of students from the Norwegian University of Science and Technology decided to make a project work about color vision deficiency. In detail they developed guidelines on how to colorize bus or subway maps taking color blindness into account.

The interdisciplinary group had ten male colorblind test persons and based their findings on the maps of London, Oslo and Trondheim.

First of all the test persons were examined on the type and the severity of their color blindness. That for the students used a set of Ishihara plates and a Lanthony arrangement test.

After that the examination was split into several different tasks like…

  • …testing which colors look the same to each test person,
  • …which are the problem areas of the maps,
  • …and also which colors would the most likely be able to distinguish on a map.
Trondheim Bus Line Colors
Trondheim Bus Line Colors

The columns of the table to the right show the different bus line colors of Trondheim. The rows are linked to the test persons and the different marks show line colors, which looked the same to the person under test.

It is very interesting to see that firstly, every person had at least one pair of problem colors, and secondly that they are often the same but sometimes can be quite different.

In the end of the report the study group formulates a set of guidelines which should be followed to increase the readability of public transport maps.

  • Make stylized maps without to much geographical information. This will ease the readability since it makes it more easy to separate the different lines.
  • Use white frames around the lines since this helps keeping the colors invariable and reduces the confusion when the lines intersect.
  • Use thick lines. Through this the eye can interpret the color better.
  • Mark the lines with numbers, especially when the line intersects with others and splits.
  • Variate the intensity of the colors. The intensity differences are also visible for persons who are colorblind. Choose therefore to use colors with distinct intensity differences. Specially when using similar colors and color combinations, which some people could see as one color. For example:
    • Brown, red/pink, green
    • Grey, red/pink, green
    • Blue, purple, red, pink, green


“Our opinion is that these guidelines will make public transport maps more easily accessible for people with color blindness, and should be possible to implement without reducing the readability for people with normal vision.”

If you are interested the report is available only in Norwegian as PDF download: Fagrapporten.pdf (8MB).

See also: Japan’s Public Facilities Making Life Easier for Colorblind and Subway Maps in general.

How does a Total Colorblind Child’s Future look like?

Total color blindness—also known as complete color blindness or monochromacy and with the scientific name achromatopsia—is very uncommon. Less than one out of 30′000 people is affected by this special form of color vision deficiency.

What if your son or daughter suffers from complete color blindness, how might a possible future look like to your child?

I just came to know my sister’s son is total colorblind. He is 12 years old.

  1. Since he is total colorblind, does it mean he sees all color in monochrome gray shades or can he see some of the colors?
  2. What kind of profession should he pursue since he is total colorblind?
  3. Is it fine for him to get work as a software engineer or a doctor?
  4. Is it fine for him to drive when he grows up?

Before answering the above four questions I would like to say a few words about complete color blindness. A young baby suffering from monochromacy will start to twinkle in bright light. Why? Because all cones which are needed for color vision and day vision are absent and therefor vision is solely based on rods. This receptors can’t see colors and are responsible for night vision. This means they are very sensitive to bright light which additionally leads to very poor visual acuity.

This means, if your child really suffers from complete color blindness he or she…

  • …needs strong sunglasses in normal daylight.
  • …has poor visual acuity.
  • …also suffers from nystagmus (nervous eyes).

1. Does he see all color in monochrome gray shades or can he see some of the colors? If you are suffering from achromatopsia you can’t perceive any colors beside black, white and fine tuned shades of gray. There is no feeling or sensation of color at all.

2. What kind of profession should he pursue since he is total colorblind? Unfortunately complete color blindness can be a huge handicap in many professions. But there are many people who showed that also a huge variety of jobs can be done with this deficiency, like Dr. Nordby an internationally recognized vision scientist, lecturer, and writer. You can find more personal job stories in the book Living with Achromatopsia.

3. Is it fine for him to get work as a software engineer or a doctor? To work as a software engineer should cause no insurmountable hurdles. Of course you might need an extra large display and adjust some color settings. But programming is a logical and not a color related job. To work as a doctor could be tougher. A doctor needs good eyesight during his work and also needs to make decisions based on colors. There might be some work which can be done as a complete colorblind person, but it won’t be easy at all.

4. Is it fine for him to drive when he grows up? Unfortunately I have to tell you that you can’t drive when you are suffering from achromatopsia. The handicaps I described above are just to big to be able to safely drive a car.

Please make sure that you also visit the very comprehensive site from the Achromatopsia network. They are also offering two books as pdf download with a lot of specific information on this very special type of complete color blindness: Understanding and Coping with Achromatopsia and Living with Achromatopsia.

Seekey – Colorblinds See Otherwise Invisible Colors

Are you red-green colorblind? Do you have a handy tool in your pocket which helps you in critical situations to tell certain colors apart? If not you might like to learn more about a tool called Seekey, which exactly can do that for you.

Seekey tool
Seekey Tool

Seekey is a little tool consisting of two different light filters: a red and a green filter. Looking through them will change the way you perceive the color of the object you are focusing on. Based on the difference in color perception through the filters and without filter you can guess the correct color.

Let us have a look at a little example: It is always very tough for a red-green colorblind like me to spot the nice orange blossoms in our green garden. Those two colors just look so similar to my eyes. With Seekey this changes. Looking at the blossoms through the red filter, they get lighter while the surrounding green darkens. The green filter changes the effect and lets all the green lighten up compared to darker blossoms.

Seekey Color Key
Seekey Color Key

There are several color keys coming along with Seekey. Through those color keys you will learn how the color perception changes when looking through one of the two filters. The table to the left shows you an example for the colors red, green, orange and brown.

Kenneth Allblom is the inventor of Seekey. He is living in Sweden and distributing the tool either directly through his web page or otherwise it can be bought at opticians and in certain boat equipment stores in Great Britain, France, Sweden, Finland, Germany, New Zealand and Japan.

A study at the Karolinska Institutet in Stockholm Sweden even showed that the Seekey tool will assist red-green color deficient persons to achieve an 86% improvement at the Ishihara test for color blindness.

Seekey is a handy tool which can help every red-green colorblind person. Visit the Seekey homepage directly to get more detailed information about this little helper.

Future Employees to Take Color Blindness Tests on Their Own Expenses

The following story was sent to me by Dave. He is slightly colorblind and while applying for a job on the way to his new career he had to pass a color blindness test.

Unfortunately the new employer wasn’t really colorblind friendly. Read his story to learn more about the way he had to walk along.

I needed to pass a medical clearance in order to be qualified for training. This was no big deal…except for the Ishihara Plates.

Needless to say, I didn’t pass the Ishihara plates and needed to take subsequent “color deficiency” testing, which I needed to pay for at my own expense. The employer requires all of their employees to pass the Farnsworth D-15 AND the Farnsworth-Munsell D-100 if they have failed the Ishihara plates.

So, I went to my eye doctor and passed the D-15 with relative ease. My doctor thought that the D-100 was extremely overkill and completely unnecessary (partly due to the fact he did not own one). So I needed to spend $659.00 to purchase one myself to bring to my doctor to get tested on.

The D-100 is an amazingly intricate test and cannot be learned. So, I prayed that I would pass. I did very well (at least I thought so) on the test and scored an Error Score of 32. Which easily falls into the range of “Normal Discrimination”. The scoring break-down for the D-100 is as follows. Error Score of 0-16 “Superior Discrimination”. 17-100 “Normal Discrimination”. 100 and above “Poor Discrimination”.

Needless to say I didn’t need the D-100 and the company wouldn’t take returns, so I happily donated it to my eye doctor.

So, thanks for the site and giving me the hope I needed to pass the test!

Thank you very much Dave for sharing your personal story with us. And all the best in your new job and with your new career.

Is My Son Colorblind?

Colorful Bricks

When your child starts to learn colors the question of color blindness often arises. Does your child understand the colors correctly? He or she is mixing some colors or can’t name them correctly. Is this color blindness or is it just to early to know?

Many mothers and fathers ask if their son or daughter has a color vision deficiency. Here are some example questions of anxious parents:

  • My son has a hard time with red and yellow. Could my 3 years old be colorblind?
  • Is it too early to tell if my 2 1/2 years old son has problems with colors?
  • When should we test our son for color blindness?

Usually it is all about sons. Because of the inheritance pattern of color blindness, males are by far more often colorblind.

I would like to tackle the question about a possible color vision deficiency of your child with the following three points:

  1. Development of color vision in children.
  2. When to test your child for color blindness.
  3. Why you should check the color vision of your child.

Before I get into the details of the above three topics I would like to say a few words about color blindness itself. In each school class there is on average one colorblind child. Red-green color blindness is the most common form while the terminology is misleading. Every normal colorblind person has a very colorful visual spectrum—just a bit less colorful. This can range from almost the same vision as non-colorblind people to a quite reduced sensation of colors, but still a colorful one.

Only if you have a complete color blindness you would have monochromatic vision. This would allow you to see shades of gray but you couldn’t perceive any real colors at all. This type of color blindness only affects one out of more than 30′000 people and you would recognize it already at a very young age.

1. Development of color vision in children. At the beginning a newborn has to develop its vision. Only after a few weeks a baby can recognize high contrasts in colors like black and white. Color vision evolves steadily and at the age of about six month they have full color vision.

At the age of two a child starts to match colors. They can give you for example a block of the same color you’re holding in your hand. As colors can be matched they still can not grasp the naming of colors yet. This starts at about the age of three years. Only then your boy or girl will name the some main colors correctly.

And it will take another one to three years to name colors accurately. It is said that a child has developed normal color naming between the age of four and six years.

2. When to test your child for color blindness. As we learned in the above section that color vision and color naming evolves slowly the question arises, when is the best moment to test your child for a possible color vision deficiency.

First of all you shouldn’t just check your child for color blindness if there isn’t any evidence for a possible color vision deficiency. It wouldn’t really help you because there is also a possibility that a color blindness test shows a deficiency if there isn’t any. So if you have some evidence, when should you test?

Test for color blindness just before your child will enter kindergarten.

Most of you will ask now, why shouldn’t I test earlier if my son or daughter shows problems with color matching and color naming? I would like to give you a few arguments, why you shouldn’t test earlier.

  • Before kindergarten-age your child might not have developed complete color naming abilities.
  • You shouldn’t push to hard on such things like color vision. Give your child time to learn and understand the concept of colors.
  • Don’t make yourself crazy with a possible and often wrong diagnosis of color blindness of a very young child.
  • Try to understand your child and don’t try to analyze everything. This way you will understand your child much better and you will be able to help him or her much better.
  • It won’t really help your child and you if you know to early about its color blindness. Because your child will not really understand it or he/she will already feel like “having a handicap”.

3. Why you should check the color vision of your child. As I said before, don’t just check in anyway but only if there is some evidence. But if you think your boy might be colorblind, let him check or try some of the online color blindness tests.

And why? Because this way you will learn more about his color vision ability AND know his main problem colors (like red and green) AND last but not least you will understand and learn how to support him and can pass this knowledge on to his teachers.

Even if there is one colorblind child per class on average most teachers are not aware of color vision deficiency and most often don’t know how to handle it. They either don’t know what they can do to help a colorblind child or don’t know the colorblind children in their classes.

If you know about the color blindness of your son, you can not only support him but also help others to understand his vision and how they can help him.

Picture taken by Leonardo Sagnotti – some rights reserved.

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