The Euthanasia Coaster is a conceptual art piece envisioning a steel roller coaster designed with the intent of ending the lives of its passengers. Created in 2010 by Julijonas Urbonas, who was a PhD candidate at the Royal College of Art in London at the time, the concept also includes a scale model. The design features a towering structure reaching a height of 510 meters (1,670 feet or 0.317 mile), requiring two minutes for a 24-passenger train to ascend. Following this climb, a 500-meter (1,600 feet) drop accelerates the train to 360 kilometers per hour (220 mph), nearly its maximum speed, before leveling off and entering the first of seven slightly clothoid inversions.

The Euthanasia Coaster is designed to exert a gravitational force of 10 Gs on its passengers, a level potent enough to be fatal. This extreme roller coaster would cause death through prolonged cerebral hypoxia, which is an insufficient supply of oxygen to the brain. The sequence of the ride’s seven inversions is engineered to maintain 10 g on its passengers for a duration of 60 seconds. This would induce a progression of g-force related symptoms, beginning with a gray out, progressing through tunnel vision, leading to a blackout, and culminating in g-LOC (g-force induced loss of consciousness). Depending on each passenger’s individual tolerance to g-forces, cerebral anoxia could occur as early as the first or second inversion, resulting in brain death.

The concept behind this roller coaster is to offer individuals an exhilarating experience prior to death, proposing a unique intersection of thrill and finality.

As of now, the Euthanasia Coaster exists solely as a scale model, and there are no current plans to initiate its construction.
[Source]