London Underground Driver testing
Transport for London (TfL) commissioned a study to examine the use of colour signals within the London Underground environment and to establish minimum colour vision requirements that can be classed as safe for underground train drivers.
Based on the results of this study, TfL designed a colour assessment protocol based exclusively on the CAD test. The new approach to colour assessment ensures that up to a third of people who would have previously been prevented from working as train drivers are now passed fit.
At TfL, the safety critical part of a train driver’s assessment is red/green vision – a number of coloured light signals of well-defined spectral composition are involved. Blue/yellow vision is also important and is part of the assessment to check for eye health.
A detailed description of how the CAD test is used in the TfL environment is given in an article written by John Ballard (Editor, Occupational Health at Work Journal).