To warn of the space between the train & the platform, London subway riders are told to "mind" this
It is no help 
being told, for example, that consciousness is subjective in the sense that it has a
... [DOC] [TLE] 'nearly dies' after falling between commuter train and the platform [PAR] Apr 20, 2016 ... A pensioner 'nearly died' after she fell between a train and the platform - because 
she did not hear anyone warning her to 'mind the gap'.