Complexity cubed

News October 09, 2001
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Even though it involves taking some pieces apart and putting it all back together again, John Hillman isn't cheating as he trie

Even though it involves taking some pieces apart and putting it all back together again, John Hillman isn't cheating as he tries to solve his Rubik's cube.


The senior structural engineer for Teng & Associates, Chicago, has certainly looked at all sides of the challenge, which involves restructuring some of the Green, Brown and Purple CTA "El" lines to match the reconstruction of historic Wacker Drive.


"This is essentially like solving a Rubik's cube," he told ROADS&BRIDGES. "There isn't a unique solution to it, but I will say given all the constraints there aren't infinite solutions available. You have to work within all the parameters and coordinate with all the attributes of the project to make sure that you have a solution that works and doesn't result in any other conflicts."


Engineers, however, have to be battle-tested to deal with problems which include:

*Restricted space for the replacement of the foundations around existing bascule bridges;


*Dealing with freight and subway tunnels, utility mains, gas, water, sewer and electric lines and fibre optics;


*Trying to make new CTA structures tie into existing CTA structures that are over 100 years old;


*Maintaining limited downtime train operations; and


*Installing new structures while maintaining or improving the vertical clearance on Wacker Drive.

"I have worked on a lot of large and unique structures in my career, but I would have to say Wacker Drive has a level of sophistication of complexity and diversity that I wouldn't anticipate seeing again," said Hillman.


For more on this story, read the October iss ue of Roads&Bridges, which includes a special Wacker Drive section.


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