This is the 'Steaming Bay'. In this scene, there are six segments of raised track that allow members to take their locomotives off the mainline for maintenance. From the Steaming Bay, a system of trolleys and switches allow a steamer to take his engine from the steaming bay to the mainline without any lifting.
In this scene, there are four locomotives that are steaming up getting prepared for a run. Unlike engines of today, steam locomotives require a long and elaborate procedure to take them from rest to a fully fired up engine with a full head of steam.
In the foreground, there are two finger-like concrete pads. These pads support the trolleys that are used to move the large 7 1/2" locomotives between a trailer and the steaming bay. These large locomotives weigh well over 1000 pounds.