A better way to measure colour vision for rail employees
The common colour vision assessment for mainline train drivers (Ishihara test) does not assess the severity of an individual’s colour vision deficiency (CVD).
This means that those who have mild colour vision issues, but who are still capable of performing their roles safely, are being excluded from some safety-critical activities.
Our research created a new two-step protocol for colour vision assessment in mainline train drivers. It uses the Ishihara test as a screener. This is followed by the Colour Assessment and Diagnosis (CAD) test. Specific pass thresholds were developed in the CAD test.
The new approach is a more accurate measure of colour vision loss. It passes more individuals with less severe colour vision loss. This protocol can be easily adopted by industry and will help reduce variability and standardise the approach to colour vision assessment in the industry.
The findings of this research have informed the upcoming changes to the rail industry medical standards (RIS-3789-TOM).
The new approach to colour vision assessment promotes greater inclusivity without sacrificing safety. It contributes to a fairer and more scientifically validated system for evaluating colour vision in prospective or existing safety-critical roles. Having a consistent approach and clear processes will reduce confusion and promote inclusivity in the railway.