The R1 (Rural) location classification in AS 2885 is pretty straightforward: areas that are either unpopulated or have only occasional isolated residences.
When the code committee was considering location classification there was some discussion of an even lower location class (informally known as R0) for truly remote outback regions. However in the end it didn’t seem worthwhile. In both R1 and “R0” areas the most likely victim of a pipeline failure will be the person who created it by digging where they shouldn’t. In other words, the threat brings its own consequences with it regardless of the fixed population in the surroundings.
The only situation in which an “R0” definition might be useful is the unusual case of aboveground pipelines. Section 5.8.3 of AS 2885.1 (and Fig 5.8.3) define the conditions under which high pressure pipelines can be installed without normal burial. Gas pipelines can be installed aboveground only in locations with zero population and managed access, and then only subject to a special safety management study. But that is such an rare situation that it wasn’t worth defining a whole new location class to cover it.
A common question about R1 areas is how to treat isolated houses that unavoidably fall within the measurement length. Do they need extra protection? That depends on the safety management study. Clause 4.11.2 of AS 2885.1 says that “localised increased protection against external interference should be provided, including increased penetration resistance where appropriate.” One common practice is to provide increased depth of cover (say 1200 mm) where the pipeline is within the 4.7 kW/m2 distance from a house and also to increase wall thickness when the pipeline is within the 12.6 kW/m2 distance from a house. But there isn’t much point increasing the thickness further if the pipe already has reasonable penetration resistance.
For existing pipelines undergoing safety management study review there is not much that can be done about isolated houses. About the only suggestion I’ve seen, which is a little half-baked, is that in-line inspection data should be given closer scrutiny for defects in the vicinity of isolated residences.
Anyway, R1 areas don’t raise many issues. It’s the other location classes that can get slightly more complicated.