This is the Free-Form Aluminum Roof on 407 TTC Subway Station by AECOM & Aedas.
To achieve this beautiful design, Kalzip XT Standing Seam Roof and Radius Track Curved Framing were used on top of regular roof deck.
The structural steel is straight, and the roof deck is straight, but Radius Track CURVES so the Radius Track Framing was used to create the Free-Form Shape.
Free-Form Exterior Roofs or Walls are never simple, but they can be a lot more affordable with off-the-shelve materials that are meant to be curved like Kalzip and Radius Track.