Is there really that much demand for buses between Sheddens roundabout and the Holiday inn that necessitates a 15 minute frequency on that section of the route?. Clarkston is always busy, but after that there generally isn't a great deal of passenger demand until the bus reaches Westwood, so imo the Sheddens to Holiday Inn via Busby section of the route absolutely could manage fine with a half hourly service (especially as there are alternative Glasgow and EK transport options on that section with the railway station). If First wanted to upgrade the 6 using newer vehicles I see no reason why they couldn't divert the current route via Waterfoot using newer Enviro 400 MMC's/EV's, and introduce a half hourly variation along the current route via Busby (perhaps number that a 6B) operated by Enviro 200 MMC's/EV's. Yes, this would still mean a reduction in capacity vs an all decker operated route, but still preferable to going all single. Obviously, the ideal solution would be lowering the road under the Busby bridge or new low height deckers, but as I'm not an engineer I genuinely do not know how much work would be involved in lowering the road, nor am aware wherever or not ADL offer a low height version of the E400EV???. If both of those options are not possible then sending a decker via Waterfoot every 30 minutes and reducing the Busby section to a half hourly frequency would probably be sufficient. Yes, you may have to rejig the timetable slightly and make the Waterfoot section limited stop, but that shouldn't be an issue since it's A and B roads. The most practical solution for the time being would just be to give the current low height E400's an internal refurb as they aren't that old and still in good condition, but whether or not that happens though remains to be seen as First Glasgow doesn't tend to give their vehicles an internal refurb all that often, and apart from the 61 branded B9's I can't think of any other refurbs in recent times.