Sentence:  A “moving platform” scheme...is more technologically ambitious than maglev <WSD>trains</WSD> even though it relies on conventional rails. Local <WSD>trains</WSD> would use side-by-side rails to roll alongside intercity <WSD>trains</WSD> and allow passengers to switch <WSD>trains</WSD> by stepping through docking bays. 
Meaning of the word marked with <WSD> tags:  A line of connected railway cars or carriages considered overall as a mode of transport; (as uncountable noun) rail travel. (from 19th c.)