Chicago has the third busiest and second longest rail mass transit system in the country. Known as the “L” for “elevated” because most of the system is on an elevated structure, eight rapid transit lines provide 24hr service at least in some parts of the system. These facts provide significant challenges for the fabrication and erection of the system’s train stations which commonly incorporated curved structural steel.
The train station at the Illinois Institute of Technology uses curved steel beams to form a tube which muffles the noise of the “L” as it passes through the campus. Underneath the tube is the McCormick Tribune Student Center designed by celebrated architect Rem Koolhaus. The challenges in fabricating this station derive from working with three independent structures clustered on one small site: the original “L” tracks and whole support structure, the tube, and the student center. Furthermore, the top of the tube is constructed of structural beams curved against the strong axis into a half ellipse with some tight radii. Lastly, the structures had to be erected with no interruption in train service.
The new Oakton-Skokie Station has an intricate pattern of interconnecting pipe to function as a canopy above the train platforms. Again, after the complex fabrication including connection plates where multi-radius curved sections intersected, the structure had to be erected with no delays in the normal train schedule.
On the design boards for the system is a new station at Cermak Road in Chicago. Once again using a curved steel design, the renderings suggest that this structure will function like a curtain wall with glass panes, but we’ll have to wait and see the final product.
