> as traffic lights and life-support systems fail.

Has anyone on life support ever died from the power going out ? I've worked at a hospital and the life support machines have internal battery backups, they're plugged into a separate outlet that is (at least) got an instant-on backup generator and possibly another battery backup. Plus, the ventilators I saw have rubber balloons on them that can be manually squeezed to breathe the patient if the machine dies. I also thought ventilated patients are also staffed by critical care nurses that have at most 2 patients per nurse. I've never heard of a ventilated patient set off in a room alone without adequate supervision.

Not saying there's no risk elsewhere in a city from power loss, but I thought hospitals had this situation covered.