Improving the Readability of Public Transport Maps for Colorblind Travelers

Report Cover

Color blindness friendly coloring of public transport maps.

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.