Exactly, they were doing all they could. Ironically these ice issues don't crop up as much if the temperatures are colder, only when they hover around zero allowing moisture to build up on the wires, and in fog theres a lot of moisture.
Where they though , from what I gather they stopped the ice breaking trams before the fog descended and then a few hours later when the first service trains went out there was too much ice on the OLE and a number of service trams failed .
If they had known about the freezing morning fog (which they really should have )
They should have either
A) not stopped the ice breaking trams until right upto the first service tram - maybe even kept them out running in between service trams .
B)Delayed the start of service so that they could run an extra ice breaking tram , and ensure that the OLE was clear .