Sentence:  The terminal station, Richmond, is managed by South West Trains, heirs to the London & South Western Railway, and here the District fades into a railway <WSD>maelstrom</WSD>, since Richmond is not only on the Waterloo-Reading line but is also the westerly terminus of the London Overground. 
Meaning of the word marked with <WSD> tags:  Any violent or turbulent situation.