In message , at
00:06:33 on Sun, 20 Aug 2017, John Rumm
remarked:

Looking at other news photos it looks like the car park was already
under renovation and that would be the most likely cause of the collapse.

eg

http://www.nottinghampost.com/news/g...tre-ncp-350253

Yup, this image shows it better:

http://i4.nottinghampost.com/incomin...TERNATES/s1227
b/190817JT1-16.jpg

The question is: when were those pit-props put there. Before or after
the collapse?? Could easily be "after", as part of the process of
evacuating the trapped vehicles.
--
Roland Perry