It underwent Imposing_obligation a partial structural failure on June 23 , 2012 , when a 12m x 24m ( 39'-by-79 ' ) segment of the rooftop parking deck collapsed Catastrophe into the building , crashing Catastrophe through the upper level lottery kiosk adjacent to the food court and escalators to the ground floor below .

Wooden escalators were gradually replaced with metal escalators on the London Underground .

Wooden escalators were gradually replaced with metal escalators on the London Underground .