railway accident in 1875 that led to occupational color blindness testing

Although more recent analyses dispute color blindness as the main cause of this railway accident, in which 9 were killed, the origins of occupational screening for color blindness are often traced to to this head-on crash in Lagerlunda, Sweden, on the night of 14--15 November 1875.

red-green detection is actually the most common form of color blindness