The Lagerlunda rail accident occurred in the early hours of 15 November 1875 about 8 km west of Linköping in Östergötland, Sweden. Unclear signalling between a station master and a steam engine driver led to a train leaving the station although another train was approaching on the single line track. 9 people were killed in the head-on collision shortly after. The station master was sentenced to 6 months of prison.

A contemporary investigation by Swedish ophthalmologist Frithiof Holmgren suggested that color blindness on the part of the driver could have contributed to the accident, which prompted the introduction of mandatory color-vision screening of railroad personnel. However, more recent analyses dispute color blindness as the main cause of the accident.^[1][2]