Pb,
Thank you again.
Theoretically Performance-Based Navigation can provide a lot of options for respite; a track along the centreline, one 1nm left of centreline, and another 1nm right of centreline etc. The trouble is we need to trial PBN routes to prove they are safe and stay within the 'containment' so that each SID could have a variety of PBN centrelines as a first step. You can't just introduce such a complex structure without interim steps.