"but I do wonder whether underground parking would at least help"
Our local Tesco (Yeovil, Somerset, UK) had a fairly large car park, and a rather strange split level two storey thing at the periphery which seems to have been designed and built for dodgy purposes and is minimally used! Around 20 odd years ago they simply put a second storey on most of it.
You need to provide walkways anyway, so you minimally encroach on those with concrete encased steel pillars (mostly for fire retardant but handy extra section anyway). It's a pretty cheap way to nearly double your parking.
Our local Tesco (Yeovil, Somerset, UK) had a fairly large car park, and a rather strange split level two storey thing at the periphery which seems to have been designed and built for dodgy purposes and is minimally used! Around 20 odd years ago they simply put a second storey on most of it.
You need to provide walkways anyway, so you minimally encroach on those with concrete encased steel pillars (mostly for fire retardant but handy extra section anyway). It's a pretty cheap way to nearly double your parking.