Selection list

The Selection list defines which links are included in the design region for a Network design run.

Only links included in the Selection list are modified during the design process.

If no Selection list is specified, the entire eligible network contained within the current model network is treated as the design region.

Behaviour

Links included in the design region:

Links outside the design region:

  • are not sized or graded by the design process
  • provide boundary conditions for the designed region
  • may impose connectivity constraints on adjacent designed links

When the Consider levels from fixed connections option is enabled, the levels of these external links are treated as fixed connections during candidate evaluation.

Connectivity effects

When a selected link connects to a link outside the Selection list and Consider levels from fixed connections is enabled:

  • the external link's levels are treated as fixed boundary levels
  • upstream, downstream, or side-branch connections may restrict feasible candidate slopes

Structures located within the design region (including pumps, orifices and weirs) provide fixed invert levels that the design attempts to connect to.

These connectivity conditions may impose additional slope constraints during candidate evaluation.

Design failure behaviour

If no feasible candidate exists for a pipe, the design process stops at that location.

Pipes processed prior to the failure remain updated in the network. The failure and the governing constraint responsible for the rejection are recorded in the Design report.

Design scope considerations

Using a Selection list allows:

  • partial network redesign
  • staged or incremental design workflows
  • testing alternative layouts within a defined region of the network

This makes it possible to redesign sections of a network while keeping other parts fixed.