There’s scope to speed up the Shotts line, but the difficult bit is threading them through Newton and Haymarket. Given the huge difference in journey time between the fast and all stations trains, I wonder if 3 semi-fasts an hour – each with a different stopping pattern, but giving all but the quietest stations at least 2 trains an hour – would work. Might break a few links, but would there be an outcry if say Hartwood to Kingsknowe was no longer possible without a change (of course there would, there always is)? Alternatively, could the Dalmuir-Whifflet extend to Edinburgh as a stopper – I’m assuming the new station at Ravenscraig is still many years away. Would miss out Bellshill and might be too long to be reliable (it’s not great as it is), but would need fewer resources. It’ll be interesting to see how they do it, it’s been a Cinderella line too long.