Editing Roller coaster (section)

=== Roller coaster design and statistics ===
Roller coaster design is another important aspect that requires a working knowledge of [[Kinematics|basic physics]] to enhance ride comfort and avoid harmful strain to the rider. Ride designers must carefully analyze the movement a ride subjects its riders to, ensuring it is within a reasonable tolerance. The human body needs sufficient time to react to sudden changes in force in order to control muscle tension and avoid harmful consequences such as [[Whiplash (medicine)|whiplash]]. Designers typically stay in the range of {{cvt|4|to|6|g-force|sigfig=1}} as a maximum for positive g-force acceleration, which increases the feeling of weight and pushes riders downward into their seat. For negative g-force, or the feeling of weightlessness, the target is {{cvt|1.5|to|2|g-force}} as a maximum. These fall into a range considered safe to a majority of the population. Lateral acceleration is also typically kept under {{cvt|2|g-force}} using various techniques including the banking of curves.<ref>{{Cite news |title=CoasterForce |url=https://coasterforce.com/physics/ |access-date=9 May 2022 |website=CoasterForce}}</ref>

Wheels are a critical part in rollercoaster design. The purpose of wheels is to keep the train on the track and to prevent it from flying off. A majority of roller coaster wheels are made from polyurethane. There are three kinds of roller coaster wheels which include road wheels, side friction wheels, and up-stop wheels. Road wheels ride on top of the track. Side friction wheels ride on the side of the track to keep the train on the track throughout turns. Up-stop wheels ride below the track and prevent the train from lifting off the track.<ref>{{Cite book |last=Hunt |first=Kristen |title=Design Analysis of Roller Coasters |publisher=Worcester Polytechnic Institute |date=May 2018 |location=Worcester, MA |pages=11 |language=English}}</ref>

Roller coasters are statistically very safe when compared to other activities, but despite all the safety measures in place, [[Amusement park accidents|accidents]] still occur. The [[International Association of Amusement Parks and Attractions]] (IAAPA) reports that a rider has one chance in 15.5 million of being injured on a ride. Also, "In a typical year, more than 385 million guests enjoyed in excess of 1.7 billion rides at approximately 400 North American fixed-site facilities". IAAPA is required to report annual ride incidents to the National Safety Council.<ref>{{Cite news |last=National Safety Council |date=August 2021 |title=North America Fixed-Site Amusement Ride Injury Survey, 2020 Update |pages=1–14 |work=International Association of Amusement Parks and Attractions Orlando, FL}}</ref><ref>{{Cite web |title=Amusement Ride Safety {{!}} IAAPA |url=https://www.iaapa.org/safety-security/amusement-ride-safety |access-date=2022-05-02 |website=www.iaapa.org |language=en}}</ref>