The [line](https://www.google.com/maps/@55.8488604,-4.266545,17z?authuser=0) they're talking about swoops down the Gorbals and connects down to the Paisley Canal and Inverclyde lines. That just happens to pass near West Street, which has been posited as the location for a potential Rail + Underground Interchange in every Glasgow Crossrail/Metro proposal for decades.