Everything old is new again: The Light Railways Act of 1896 also propsed rail lines built to less then mainline standards (often narrow gauge) to get transport links to otherwise unconnected locations. https://en.wikipedia.org/wiki/Light_Railways_Act_1896 comment edited because I fat finger editing the submit button
They're using "Standard rail components, innovative construction" - standard gauge rail, but laid over a foundation of slab ultra-high performance concrete (UHPC), which allows for the shallower foundation / avoidance of utilities relocation.
Using UHPC to rethink infrastructure is the big story here, I think.
