Not being totally au fait with the actualities of the area, it appears from what my historical researches as part of running the Closed Stations Journey quiz that two former railway companies had lines with stations in the area of Lugton and that one of these lines had the now-demolished Gree Viaduct upon it:-
Lanarkshire and Ayrshire Railway
Lugton High...Opened in May 1903 and closed in July 1932 (83 years ago)
Glasgow, Barrhead and Kilmarnock Joint Railway
Lugton...Opened in March 1871 and closed in 1966 (49 years ago)
Thank you for your concern Paul but no viaducts between Lugton and Neilston-just. Gree Viaduct is about half a mile the other side of the GBKJR. I didn't even know it had been demolished. Very sad when these heritage structures are lost.