Developing a Mental Fatigue Questionnaire for public transport bus drivers

Driver’s fatigue is a major factor contributing to the prevalence of road accidents. A vast number of city dwellers in most countries use public transport bus services to move around the city. Driver’s fatigue causes job burnout and affects the risk of a traffic accident injuring the public. Several methods have been used to date for evaluating mental fatigue; however, using questionnaires tends to be a less time-consuming and more accessible technique. The present study was therefore conducted to develop a mental fatigue questionnaire for public transport bus drivers. The study was conducted based on the criteria used for qualitative research. Semi-structured interviews were held with public transport bus drivers using probing questions and data were collected until their saturation so as to enable access to a direct description of mental fatigue by the bus drivers. Data saturation occurred with 30 interviews and sampling was then discontinued. The analysis of the interviews led to the extraction of the themes and an initial list of questionnaire items was then developed. The psychometric properties of the questionnaire were then evaluated through examining the content validity and internal consistency of the items. The content validity of the items was calculated using Lawshe’s table. A minimum CVR of 0.99 and a minimum CVI of 0.75 denoted an acceptable content validity for the items. To determine the internal consistency of the items, 200 bus drivers completed the final version of the questionnaire. The data obtained were then analyzed in SPSS-16 using Cronbach's alpha to measure the reliability of the questionnaire and considering an acceptance level of 0.7. The interviews conducted at the beginning of the study with 30 drivers led to the emergence of an initial list with 26 items. A total of 9 items with a CVR less than 0.99 were omitted from the list and 17 items with adequate simplicity, clarity and correlation between them and which had a minimum CVI of 0.75 were kept. The questionnaire had a Cronbach's alpha value of 0.87 and was therefore considered a reliable tool. The questionnaire developed in this study has a good validity and reliability and can therefore be used to assess mental fatigue in public transport bus drivers.