Optimal luminance of internally illuminated wayfinding signs

For wayfinding signage it is essential that the sign is conspicuous and that the messages it contains are legible. This study investigated the optimal luminance for internally lit wayfinding signs in Swiss railway stations. The results demonstrated first, that increasing the light output of the LEDs inside the sign improved conspicuousness of the signage against its surroundings, and second, that considerable improvement of the signage's legibility could only be observed until its white text reached a luminance of 100cd/m(2). Hence, for internally illuminated signage in general indoor situations, a luminance of 100cd/m(2) is recommended. Very high luminances should be avoided because even if conspicuity is improved, legibility might worsen.