Central line (London Underground) interchange, it was ruled out on grounds of cost, the disruption it would cause to the Central line while being built and because the platforms would be too close to sidings at Liverpool Street and would not be developed until after Crossrail is fully operational. The developers of the "First Central" business park at Park Royal, west London, were planning a new station between North Acton and Hanger Lane. This would have served the business park and provided a walking distance interchange with Park Royal station on the Piccadilly line. This is not being actively pursued; London Underground has said
London Underground infrastructure were originally maple wood, then aluminium from 1963, and this had been replaced with plastic or rubber following an increase in serious injuries following falls. However, following the King's Cross fire, aluminium treads have been used. There are 426 escalators on the London Underground system and the longest, at , is at Angel. The shortest, at Stratford, gives a vertical rise of . There are 184 lifts across the Underground, with 72 stations having step-free access from street to train. Major efforts have taken place to improve accessibility across the Underground, with the Jubilee line extension having lifts from opening