 Vortex was a stand-up roller coaster that officially opened on March 9, 1991, as the second coaster from the company Bolliger & Mabillard following Iron Wolf at Six Flags Great America.Although the layout differs, Vortex is generally the same size as its (former) namesake, Vortex, located at sister park Carowinds in Charlotte, North Carolina.As the ride had gotten rough with age and wasn't particularly smooth anymore, it made a good conversion candidate to improve the experience in the space constrained park.