Photo from Bob Morris (firstname.lastname@example.org)
The sand house/tool shed is a huge sandbox covered with the upper shed where I am guessing the sand pumping mechanism is housed to deliver it through overhead pipes to the west turntable approach track in front of the shed and the servicing track which is next track to the north.
These are progress pix as of 2020-01-03 of the components of the sand box which are being built separately to allow better painting and easier rebuilding as I make mistakes.
This is how they go together without gluing.
The board and batten shed structure that fits atop the sandbox will be next. I have estimated the height of the shed wall atop the sandbox as 10 feet and the apex of the end walls as 13.5 feet.
If anyone has better information on dimensions please let me know at smadanek44g.com