In 2015 I had the honour of contributing to the graphic standards for Translink, the transportation authority for the Greater Vancouver Regional Area. Since one of their pillars is accessibility, a large part of the initial audit was a review of how the visual assets performed among people with disabilities.
Simulations demonstrated that the colour coding used in the wayfinding systems was illegible to a very significant portion of the riders (~ 8% of males are colourblind which translates into 21 million individual annual journeys (Translink p3)). Minor shifts in the colour values significantly improved the perception of colours.
Full case study here:
Translink (2018) Transit Service Performance Review, From https://www.translink.ca/-/media/Documents/plans_and_projects/managing_the_transit_network/2018-TSPR/2018-Transit-Service-Performance-Review.pdf?la=en&hash=0A0388E9606F37209443E060FC7044AC0A46E0BC
Colour Blind Awareness Org (2013) Colour Blindness From http://www.colourblindawareness.org/colour-blindness/