Well before the first winning athlete is acknowledged at the 1996 Summer Olympics in Atlanta, a construction team building a public stadium for the much-anticipated event has put in a performance worthy of a gold medal. Using a curb-and-gutter slipform paver equipped with a custom two-step mold, a crew of seven slipformed 22 rows of risers in just two weeks.
"There was no way in the world to form all the risers by hand. The time frame was impossible," says Dr. Edward Haight, the consulting engineer on the project. Looking for alternatives to hand forming led the project engineer to a compact curb-and-gutter paver with three 12-inch-wide tracks. This method had been used successfully at Camden Yards, the Baltimore Oriole's stadium.
With its right rear post extended vertically 26 inches, the slipformer was able to extrude concrete through its two-step mold while riding on steps placed the previous day. A laser monitored the mold's elevation to ensure that the slipforming operation met stringent step-height requirements.