Friday, April 10, 2009

1879: Color-blind Train Engineers Fired

In 1879 the New York Times published some of the earliest articles related to color-blindness and transportation. Since this time period was for the most part pre-automobile, the discussion focuses on train engineers and their abilities (or lack thereof) if they suffer from color deficiencies.

The discussion in these articles is a response to European countries (Switzerland, Italy, France) that had tested their locomotive engineers for color-blindess and discharged from service those testing positive.

January 26, 1879
"To a color-blind person any color that looks dark seems red, a brighter color seems green, and a color still brighter appears white. Test a color-blind engineer, and he will, in many cases, tell the signals at once, for if he sees a dim light he knows that means stop...He is guided merely by the intensity of the light."

This is a relatively accurate description of how I perceive Red-Yellow-Green traffic signals, using intensity (combined with placement) to support my deficient ability to discriminate the colors.

"Mr. Leonard...was then asked to pick out different shades of the same color, and, as he is affected with color-blindness, he placed in a mass shades of all colors - blue, green, and red - to the great amusement of the committee and spectators."

Wait...what? To the great amusement?

September 3, 1879
"Complete protection against this source of danger [color-blindness] can be secured only by eliminating from the employes of railroad companies and other passenger carriers all persons whose duties require perfect color perception, and who are deficient in this respect."
"Every railroad employe should be carefully tested for color-blindness by a competent expert, and all found deficient should be removed from posts of danger."
I don't know how the railroad companies handle this issue now, but it's very interesting to see the "remove from post" attitude of 1879.

November 30, 1879
"[Color-blind engineers] have a specially acute perception of the luminosity of colors and they will distinguish red and green not as red and green, but as differently strong. In this way the railway engineer may go on safely for years, distinguishing the red and green lanterns by their brightness. But finally comes a night when their relative brightness is altered by moisture upon the glass, by snow, or hail, or dust, and then the mistake is made, te crash follows, which the least glimmer of red perceived as red, or of green perceived as green, would have avoided."

There seemed to be a general sense of fear, that the color-blind engineer was unable to operate safety in all conditions and should be removed from service. An extrapolation of this theory would question whether color-blind drivers should be operating motor vehicles on today's roads. Thoughts?

Monday, April 6, 2009

Retroreflective Backplates - Frankfort, KY

I have the pleasure of speaking about traffic safety in Kentucky later this month, and I've been in contact with some of their engineers. I had heard about some retroreflective backplates in the state, so I received some information from the transportation officials.

Notice the huge difference between the signal heads. The signal on the right, particularly for one with color-deficient vision, could be any number of lighted roadway items (or even something else). It is so much easier to distinguish the others as traffic signals, and to show you that the TOP (red) indication is lit.

Here is another application where they did not fully outline the signals, but put strips around. Officials in Kentucky told me this application does not appear as effective at night (but I wanted to show it anyway).

In May 2008 the Kentucky Transportation Center completed a research report on low-cost safety countermeasures, including various alternatives of traffic signal backplates (yellow backplates with black heads, yellow backplates and yellow heads, etc.). The report can be found here: