Measuring the usability of safety signs: A use of System Usability Scale (SUS)

System usability scale (SUS) was initially developed as a tool for measuring the subjective usability of industrial systems evaluation. The SUS has now been used for various evaluations such as voicemail system, virtual keyboard, paper ballots, mobile phone, and website. Usability is a critical parameter for considering the effectiveness of safety signs. However, the application of SUS for usability assessment of safety signs or other graphical symbols had never been seen. This study was undertaken to investigate how the SUS could be used for determining the usability of safety signs. Three hundred and ninety-eight participants (17-58 years old) were asked to complete a self-administered questionnaire on safety sign comprehension first and then SUS which was modified in accordance to the unique contexts and functions of safety signs. The results showed that the SUS offers a valid and robust measurement for practitioners to measure the usability of safety signs. Besides, the SUS provides valuable benchmark information about the comprehension performance of safety signs. Moreover, the SUS is a point estimate measure of usability which can be used to positively supplement a usability testing and evaluation for safety signs quickly and easily. Overall, this study would serve as a valuable reference on assessing the usability of safety signs and other graphical symbols with the SUS instrument.