Table 1 Example grouping rules for...

Table 1

Example grouping rules for intervention candidates

Grouping rule	Object type	Explanation	Relevant attributes
Facility quantity	Facility	Intervention candidates of a given category are grouped together to consider manufacturer discounts on large orders. Objects do not have to be spatially proximate (i.e. located in the same facility).	Category ID
Facility contiguity	Facility	Facility objects in the same functional process as an intervention candidate are grouped together to consider reduction in fixed costs (downtime, set-up).	Process ID
Pipe contiguity	Pipe	Groups of contiguous pipes belonging to the same subnetwork and containing an intervention candidate can be selected using geographic information system (GIS) data to build a graph object to represent pipe connectivity. A threshold value for the DOS is used to limit the number of unique groupings considered. A degree of zero refers to the pipe object itself (no grouping), a degree of one refers to groups containing an intervention candidate and one of its immediate neighbours and so on.	Pipe connectivity (GIS data)

Grouping rule	Object type	Explanation	Relevant attributes
Facility quantity	Facility	Intervention candidates of a given category are grouped together to consider manufacturer discounts on large orders. Objects do not have to be spatially proximate (i.e. located in the same facility).	Category ID
Facility contiguity	Facility	Facility objects in the same functional process as an intervention candidate are grouped together to consider reduction in fixed costs (downtime, set-up).	Process ID
Pipe contiguity	Pipe	Groups of contiguous pipes belonging to the same subnetwork and containing an intervention candidate can be selected using geographic information system (GIS) data to build a graph object to represent pipe connectivity. A threshold value for the DOS is used to limit the number of unique groupings considered. A degree of zero refers to the pipe object itself (no grouping), a degree of one refers to groups containing an intervention candidate and one of its immediate neighbours and so on.	Pipe connectivity (GIS data)