Sentence:  A “moving platform” scheme...is more technologically ambitious than maglev trains even though it relies on conventional rails. Local trains would use side-by-side rails to <WSD>roll</WSD> alongside intercity trains and allow passengers to switch trains by stepping through docking bays. 
Meaning of the word marked with <WSD> tags:  To move, or cause to be moved, upon, or by means of, rollers or small wheels.