Sometimes operational reviews are triggered by a peak in SPAD events. For example, Period 3 in the spring of 2018 saw a significant increase in the number of SPADs compared to previous years. A review of 35 of these SPAD investigations was carried out using the 10-incident factor framework. This identified that several changes across the industry coincided and contributed to this peak. These included: re-signalling schemes, issues with vegetation management and timetable changes.