this blog that it could be questionable whether yellow was a sensible colour choice, saying that if you were to look at the yellow paint in a location where you cannot see how it forms the word “Down” you may mistake the paint for double yellow lines, signalling caution to drive in that direction.
Ralston & BauRalston & Bau is a design studio that designed interesting wayfinding for the Storehagen Atrium building in Norway in 2011. The Storehagen Atrium is a 5000 m2 governmental building. The wayfinding system they designed for this building was heavily inspired by the underground signage. Strong colours and graphical shapes are dedicated to each floor and insinuation. They wanted their signs to be universal, to make the system easy to understand for any user, such as people with visual impairment.
Colours begin in one place, explained at the start with adjoining text and numbers to show which section of the building they represent. Users can then follow their colours to their end destination. This a wayfinding technique that I have seen in buildings, such as the Worcester City Centre Campus and by local doctors. I have always found that they work very successfully.