Why are Clay Pipes used in Chicago and required. After last weeks Earthquake in Illinois I can only see them cracking, shifting, or dropping? What is stronger and smarter then clay pipes?

To tell you the truth I live just outside of Chicago and am not aware of this code. Are you talking about sewer drains to the street? For many years Chicago required plaster and electric conduit, not because of drywall or Romex being unsafe, it was a strong union things with Daley, the other Daley.

I am not a plumbing expert but we used miles and miles of clay pipe for highway underdrains that were designed to drain water from the road sub-base. There was a gap between the ends of the pipes to collect mostly water coming up as the water table got higher. That was in the 60's and 70's. The last I knew of they were using the corrugated black drain hose (6" perforated). Every time we would excavate around the clay pipe it got broken. Im sure it was used to save bucks.. Just the weight of a large pickup driving over it would break it. But it was cheap and on an intersate there might be 40 miles of drain in a 10 mile road section. I think PVC is better but I don't know the codes. Maybe there is a big clay pipe manufacturer in your area who has a lot of clout. I wouldn't use it for anything.

Clarification: A large pickup driving over a backfilled trench would sometimes break the pipe".

I'm originally from the Rockford/ Beloit area. Terra-Cotta,(clay) pipes were cheaper back in the depression and so were used outside underground. Then came cast iron and a pipe called Orangeberg that was fiber coated in tar. That didn't last too long and in came ABS. ABS didn't hold up to well under the hot Florida sun so we went to PVC where we are today. And you wouldn't know this much if I didn't feel chatty this morning. Cheers, Tom