Do we really want to make all existing noisy graphs razor roads? An alternate, lazier solution would be to do an update that sets the abslnw = current lnw and then be done with it.
There’d be no more growing or shrinking, but it wouldn’t look like a massive change – save that for later when we’ve got true YBHP. Then we don’t have to do transforms on road matrices. (Well, not yet. We’ll have to transform road matrices to change to YBHP anyway, so might as well delay for now and change status quo as little as possible for existing noisy folks. For now.)