To the best of my understanding, the structures on the roof are related to the scaffolding required for the brickwork on the track side of the substation. This part of the job must be frustratingly tedious since it can only be carried out on weekends or for a few hours between rush hours each day, while the Purple Line is not running to the Loop.
|Top of the world, Ma!|
Meanwhile, the one-story anteroom to the substation got some nice-looking
security grilles for the lunette windows.
|Installing the grilles on the lunettes.|
|Here's how the grilles looked once they were fully installed.|