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
http://tr.im/iz45
"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
http://tr.im/iz1W
"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
http://tr.im/iz24
"[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?
I just read this, and laughed out loud at the quote "to the great amusement of the committee and spectators". Spectators? What where they doing? Cheering him on and then booing him if he got a color wrong.
ReplyDeleteIt's a side-show thing, like when people asked me last weekend "What color is that? How about this?"
ReplyDeleteI'm not bothered by it, but the purpose of it for the "audience" is typically interest/curiosity/amusement.
I think it generally viewed that if you are "Colorblind" you cannot see these shades of color,I cannot pass the Ishihara book for the life of me but have done further testing,I am a locomotive driver and also hold a Commercial Pilots licence with no problems indentifying colors in my careers.I dont think we should be outed from any career until on job testing has been done and your ability to do that job noted.
ReplyDeleteSteve - I agree that colorblind tests often have little to do with real-life abilities.
ReplyDeleteI also can't pass traditional colorblind tests but have worked as a Traffic Engineer for ten years. My background in this area and the general lack of discussion about colorblindness in transportation were the catalysts for this blog.
There are misconceptions about those with color vision deficiencies, and I hope to do two things:
1) Expose those misconceptions
2) Learn about ways to address real issues that affect colorblind motorists.
Thanks for sharing your experience.
Steve - I assume you have a mild colour vision anomaly, such as deurotanomaly, which does have little to do with real world abilities. That train driver sounds like a daltonist to me. I would suppose that the rail company employing him was unaware of his red-green confusion.
ReplyDeleteBack when the accident happened, train signals were of the semaphore type which required the driver to learn two different colour systems for day and night. But modern colour light signals only use the same three colours as traffic lights. Those three and blue are the colours used by the railways, which would be unlikely to interfere with the mildest types of colour anomaly. But it may well be that you need greater visual acuity to achieve a similar performance so it's worth mentioning.
Isn't this why they went to multiple lights, so the position of the light provides a cue?
ReplyDeleteHi Resuna - I'm not sure of the exact layout of the 1879 signals, but I would imagine it was laid out in some sort of pattern. I assume that, at the time, there was so little known about color vision deficiency that it was easier to fire the employee and move on than to understand how his vision deficiency would affect (or note affect) his ability to perform the work.
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