All of us are probably familiar with the ubiquitous traffic light configuration shown below left.

When I was in China several years ago, I noticed a new "modern-look" configuration (below right) installed everywhere in the new technology city of Teda.


Does the new look work better? It certainly looks cool, if you had normal colour vision!

In the traditional design, the distinct positions of the lights, in addition to the colour of the lights, communicate the signalling intent. It is a built-in redundancy crucial to people who have deficiencies in their colour vision. In the new design, this functionality is lost.

Sometimes, "improvement" can be a step backwards.