Summary
A passenger on London’s Elizabeth line was forced to run several meters along a platform at Ealing Broadway station after his hand became trapped in the closing doors of a departing train on 24 November.
Railway staff intervened to pull him away, and the train stopped after moving 17 meters. The passenger sustained minor injuries.
The Rail Accident Investigation Branch (RAIB) is investigating the incident, part of a series of similar “trap and drag” cases, to improve safety measures.
Transport for London and the operator, MTR, are cooperating fully.
On underground lines, the PSDs are mostly for air-sealing. It allows you to air-condition the platforms without trying to cool the tunnels, and it helps the piston effect of moving trains pull air through the tunnels, rather than just swirl air around each platform.
Also probably helps for fire engineering.