KiwiRail provided a draft document that demonstrated its proposed risk-ranking system for assessing the slip hazard risk along the rail corridor. It included a method for assessing potential groundwater conditions, slope stability, soil type, surface cover, slope alterations and rail traffic and outlined a framework to come up with a risk rating. The proposed rollout of this system was over the next 2 financial years but this had not been confirmed at the time of writing. Analysis of available data such as rainfall, river flows and slip activity can be a useful activity to complement the proposed risk-ranking system for determining slip hazard risk, but this data is not currently used by the rail industry. Until the risk-ranking system has been completed, the risk to the rail network from unpredicted slips is likely to be higher than is reasonably acceptable.
The Commission recommends that the NZ Transport Agency work with the rail industry to implement a risk-management system for the slip hazards along the rail corridor.
