Ok, very curious of others' metrics and hueristics for actions that are defensible. Mine are probably composed of:

  - Net degree of suffering imposed (+ nth-order suffering imposed on eg. family)
  - Thus, nervous system pain receptor net effect (cat>lobster)
  - Age of individuals and thus life-years saved (baby>elderly)
  - Weight of burden of (in)action on own life (++suicide risk)
  - Confidence that the train will act as proposed
  - Value of human life being absolute over non-life (human>bigMoney)