The story of a warning sign at Farringdon station

I noticed a big yellow sign warning at Farringdon Station, giving drivers an important message to do something. When there’s a message added after the fact, whether it’s hand written on a dashboard, a post-it note on a computer monitor or a big poster at a train station, it’s a usually sign there’s a design problem.
After some research on Wikipedia, the Pantograph is pretty important element of the train as it provides power. In this case, it provides power to the train outside of central London where there’s not a third rail powering the tracks.
pantograph (or “pan“) is an apparatus mounted on the roof of an electric traintram or electric bus[1] to collect power through contact with an overhead catenary wire.
So why is there a warning telling drivers to lower it? What happens if they forget to lower it? After a quick google search, I found an incident at Blackfriars in January 2014 which caused major delays after the holidays and guess which station they were coming from… yep, Farringdon!
‘Today at 10am a Sevenoaks-bound service broke down at Blackfriars railway station after one of the pantographs, used to collect power from overhead lines north of Farringdon, hit the ceiling.
Interesting that a simple warning sign at a station has a much bigger story.
With thoughts of designing experiences and users not reading anything, I question the effectiveness of a sign and trusting that the train driver will read and respond to it every time. It may provide a short term fix but ultimately this needs to be incorporated into the design of the trains and the platform to prevent the train from continuing when the pantograph needs to be lowered.