Every other year, the TSB considers a number of factors. We look at accident and incident statistics to identify patterns. We review the recommendations that have not been implemented, as well as the TSB's concerns. We also consult our staff about their recommendations on what should be added to or kept on the list, or what issues should be removed from it. We also monitor other issues that are not on the list. When we add something to the list, however, it is because we feel that the risk is sufficiently high, that the addition is appropriate and that the corrective actions we called for have not yet been taken.
When it comes to the transportation of flammable liquids, we have two requirements: risk analysis and risk management by railway companies, and the accelerated removal of the least crash-resistant tank cars. Once industry and Transport Canada met those requirements, we removed that issue from the watchlist. A simple activity increase does not in itself justify us keeping an issue on the list. If we believe that the risk is sufficiently managed, we can remove it from the list. However, we continue to monitor it, especially in the case of oil transportation by rail, which is on the rise.