It’s a lesser known fact that one in ten caucasian males have colour blindness. In networking, we often rely on colour diagrams and coloured cables for key services in critical environments. And yet, many people prepare diagrams and cabling plans using colours that will make it difficult to use for colour blind people, and these can lead to errors for our so-called critical infrastructure.
The two most common forms of colour blindness are:
- Red-green deficiency (deuteranopia). This is the most commonly diagnosed deficiency. People with this condition cannot distinguish certain shades of red and green.
- Blue-yellow deficiency (tritanopia). This is a rare condition where it is difficult to distinguish between blue and green. Yellow can appear as a pale grey or purple.
Testing for Red-green deficiency (deuteranopia) is quite simple through the use of colour blot cards. If you can’t see the numbers in the image below (for example) then you have the problem.
Although you should always consult a professional, there are any number of websites that have sample screening tests for a quick check to see if you have the problem.
Where this matters
I have deuteranopia, and occasionally, there are items on network diagrams that I simply cannot see, and for certain types of high density cabling (think 100 core cable bundles) I cannot differentiate between the colours of some cables. Someone has chosen colours that make it difficult to see the data on the page, cable sheath or whatever.
Where this matters is in mission critical designs for high availability networks. It’s possible to put information or data that could be missed by a perfectly competent individual when scanning a document (either on paper or on a computer screen, it makes no difference). It’s also possible that a colour blind person may not use the correct cables for a given task, thus causing sequential failures. And so on.
Take an example of traffic lights, although most people can see at least some red/green there are some people who cannot see the colours at all. The design of traffic lights is such that they are ALWAYS vertical, and the contrast of light is detected. So even if you can’t see the “RED” light, you will see the contrast of bright / dark in the right location.
That’s the worst case for complete colour blindness, but that’s rare condition. And traffic lights are designed to handle it.
Rules of Thumb
So here are some rough and ready rules of thumb for you to start thinking about:
- if you are building mission or life critical designs, then get everyone tested. A one in ten impact rate is very high. At least, use the Internet sites for a preliminary screening.
- when preparing design diagrams, choose high contrast design colours so that data will not be lost.
- avoid using red and green colours where you can.
- choose blue, yellow, green colours instead.
- avoid using red and green directly next to each other.
- there is no cure for colour blindness
- people will varying degrees of colour blindness. I see red and green more or less OK, but I have a lot of problems seeing red/green shapes together. Don’t assume you know what other persons condition is.
- If you are colour blind, then tell people. Most people don’t know.
The EtherealMind view
- Human Infrastructure is the most important asset in functioning computer system. Hardware and software come second to the people. ( This is often forgotten ).
- If you are really building critical infrastructure ( which very very few busienss actually are, mostly they are just pretending), then environmental issues like personal safety, tiredness and motivation affect performance and the business outcomes.
- colour blindness and other medical situations are just part of planning for an infrastructure.
- find out if you are colour blind, understand what mistakes you might make, and work to eliminate them.
- people matter. Even managers and marketing people matter. But engineer people have different requirements though and we need to be engineering ourselves to get the best performance.
Other posts in the series
- My New Diagram Colour Scheme "Old Disco Style"
- On Diagrams and Information
- Colour Blindness, Network Diagrams and Reliability
- Designer or Engineer, Artist or Painter
- Network Diagrams: Rotating Text on a Line
- Network Diagrams: Tips for Printing from Visio
- Network Diagrams:Zones on a diagram with Visio shape union
- Network Diagrams: Drawing complex VLAN Networks with IP Addressing
- Network Diagrams: Drawing Freehand Curves (and then fixing them)
- Network Diagrams:Aligning Shapes
- Network Diagrams:Locking the Background Shape
- Network Diagrams: Labelling an VLAN/IP Segment
- Network Diagrams: VLANs and IP Subnets
- Network Diagrams: Drawing the Background Shape
- On the Art of Network Diagrams and Presentation