The Lagerlunda accident is usually considered the first really serious railway accident in Sweden. The accident occurs on the night leading up to 15 November 1875, when two trains accidentally end up on the same track and collide head-on. Nine people are killed and several injured. The locomotives are completely destroyed, as are most of the carriages.
A theory emerges that the accident occurred because one of the drivers was colour-blind and misinterpreted the signals. Opinions are divided on whether this was really the case, but train crews nonetheless begin to be tested for colour blindness, using samples of different coloured yarn and other means.