An analysis of the content of questions and responses in incident investigations: Self reports in the investigation of signals passed at danger (SPADs)
1. Human Factors Research Group, Faculty of Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK;2. Transnet Freight Rail, Wolmarens Street, Johannesburg, South Africa;3. Network Rail, Melton Street, London, UK