Terrain coding is an operational risk evaluation strategy that relies on detailed terrain identification such as clear definition and communication of routes or zones and their boundaries.

This is different from terrain identification /classification where the severity of the terrain with respect to the exposure of the element at risk is categorized (example ATES rating map). A subdivision of an operation’s permit area into ATES polygons has detailed enough resolution of terrain identification to apply terrain coding, though smaller subdivisions may be appropriate if any of the descriptors have a direct effect on operational activities (example, inaccessible islands within areas of higher severity).

Using terrain coding in operations reduces the effect of biases on field decision-making. It’s a process during the pre-field trip process to utilize the collaborative power of a team under less demanding time restraints to code locations or areas open (green) if it fits within the Operational Risk Band (ORB) or closed (red) if it doesn’t based on the current and forecast hazard and risk scenarios.

Fitting within the ORB means that the residual risk following applied mitigations is acceptable. In this sense, closed ski area runs that are opened after control is another example of terrain coding. Coding specific terrain in a workplace example may use descriptors of access requirements (Conditional Access: only snow safety teams, no other individuals). Coding something open indicates that given the current hazard, an element at risk within some operational contexts, logistics or objectives may necessitate a choice of terrain to be made in the field versus a pre-trip meeting. This still requires a detailed operational terrain catalog and established criteria to reduce the effect of biases on field decision-making.