Fourth-dimension roller coaster

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Fourth-dimension roller coasters (4D) are steel coasters where riders’ seats rotate independently of the track. This makes it possible to experience inversions without the track itself turning upside down. Some 4D coasters have seats that rotate in a controlled way using extra rails on the track, while others are free-spinning and rely on ride forces for most of the rotation.

The first 4D coaster built was X2 at Six Flags Magic Mountain, which opened in 2002. It was originally named X and was designed by Alan Schilke with concepts patented by John F. Mares. Arrow Dynamics produced the ride, using two rails to steer the seat rotation. The prototype X faced technical problems and financial trouble, and Arrow later went bankrupt. Arrow’s coaster division became S&S Arrow after a buyout by S&S Worldwide. X2 later reopened in 2008 with lighter trains and improved reliability.

Other early 4D coasters include Eejanaika at Fuji-Q Highland in Japan (2007) and Dinoconda at China Dinosaurs Park (2012). The Intamin ZacSpin, launched in 2007, offered a different design with seats that rotate more freely and without the extra rails, often causing a different ride each time. It also faced complaints about rider comfort due to how it rotated.

Following these, several parks added similar coasters: Kirnu at Linnanmäki (2007), Inferno at Terra Mítica (2007), and Insane at Gröna Lund (2009). In the United States, Green Lantern: First Flight at Six Flags Magic Mountain (2011) used a ZacSpin-like layout. In 2012, S&S Worldwide introduced Free Spin, where two seating rows rotate independently and magnets can influence inversions. Batman: The Ride at Six Flags Fiesta Texas became the first 4D Free Spin coaster in 2015. Intamin released updates to their 4D designs in 2016.

In 2023, Pax, a Russian ride maker, unveiled two shuttle-style 4D coasters. The smaller version uses an outside spike and a 16-passenger train, while the larger version uses an inside spike with a 20-passenger train; both have rotating seats and a stacked track layout.

There is debate about what counts as an inversion for records. Guinness World Records recognizes Eejanaika’s 14 “inversions,” but some records bodies count only track inversions, which would point to The Smiler at Alton Towers as a holder of that record. Regardless of the counting method, 4D coasters are known for their spinning seats and the unique experience of inversions without turning the track upside down.