ADD▸ (Automatic Dropping Device) is only a protection system that hopefully will safeguard the pantograph
if the wires run out. Once activated the Pan will stay down and can only be reset by a
fitter. The roof strike at Blackfriars is a bit of an anomaly as the 319 would have had to be on DC▸ (Direct Current) power to get up that severe incline.
I have seen the procedure on IEP▸ (Intercity Express Program / Project. This will offer more capacity on routes, save money, give a consistent and safe service and meet customer requirements. Intended to replace HSTs.) trains for changing from AC▸ (Alternating Current, or can mean Air Conditioning, depending on context. The second meaning is often used in a railway context and more generally) to Diesil mode. It's a one button job but just relies on the driver's route knowledge and lineside signage.
This sort on mishap will happen from time to time until ERTMS▸ (European Rail Traffic Management System. A future railway signalling system, with equipment located in the driver's cab, rather than lineside) is up and running. Then the system will prompt the operator and if necessary stop the train if no action is taken.