Darwin Designer determines the size or rehab action for pipes. It is unlikely, however, that a large pipeline will change diameter every block along its route. Plus, if fewer pipes were being sized, optimization will happen faster than if a larger number of pipes were sized. Therefore, Darwin Designer uses the idea of a pipe group or rehab group to group pipes that will attract the same design decision. At the end of a run, all of the pipes in the same design group are given the same diameter, and all of the pipes in the same rehab group receive the same rehab action. This is both logical and more efficient from a computational standpoint.

For a pipe to be considered a candidate for design or rehab, it must be placed in a group. This is done on the Design Groups or Rehab Groups tab when the Design Study is highlighted. (When the Design Run is highlighted, you choose which groups are to be considered during that run.)

You must insert at least one pipe in each design group. There is no absolute rule for deciding which pipes belong in a given group. Usually it is the set of pipes that will be laid with the same diameter and at the same time, but it can also be smaller groups than that, and in the case of smaller design problems or academic exercises, it may be only 1 pipe per group, which is easily expedited with the Create Multiple Design Groups selection. The down side of adding every pipe to its own group, however, is that this can be computationally inefficient and potentially leads to a pipeline that is say 12 in. for one block, 8 in. for the next, 6 in. the next, etc., which may be a theoretically least-cost design but is not a solution that is likely to be installed. Ultimately the choice comes down to a trade-off between number of pipe groups (and size of the optimization problem) versus constructability of the design through the potential for different pipe sizes adopted for each group.

Design Groups tab

Rehab Groups tab

To add a new design or rehab group

To make changes to a design or rehab group