Track 11a was the short stub track between the tracks 10 and 11 that long distance trains used, and the Ayr/Inverclyde tracks. But how was this track actually used in regular traffic? I've seen photos from the 80s with locos parked there, and photos from the final years before the track was removed in the remodelling for the cancelled Glasgow Airport Rail Link, with 318s and 156s parked there. Did trains actually run to/from the track (it looks like it could fit two coupled three-car EMUs)? Or was it just used for short-term parking of trainsets/locos?
