# Roller coaster

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A typical roller coaster

The roller coaster is a popular amusement ride developed for amusement parks and modern theme parks. LaMarcus Adna Thompson patented the first roller coaster on January 20, 1885. In essence a specialised railroad system, a coaster consists of a track that rises and falls in specially designed patterns, sometimes with one or more inversions (the most common being loops) that turns the rider briefly upside down. The track does not necessarily have to be a complete circuit (the antonym of complete circuit is "shuttle"), though some purists insist that it must to be a true coaster. (Note that not all thrill rides that run on a track are roller coasters). Most coasters have cars for two, four, or six passengers each, in which the passengers sit to travel around the circuit. An entire set of cars hooked together is referred to as a train.

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## Mechanics

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A roller coaster at Movie World, Australia

The cars on typical a roller coaster are not self-powered. A standard full-circuit lift-powered coaster works like this: After leaving the boarding area (station), the train is pulled up with a chain or cable along the lift hill to the first peak of the coaster track. Then potential energy becomes kinetic energy as the cars race down the first downward slope. Kinetic energy is converted back into potential energy as the train moves up again to the second peak. This is necessarily lower as some mechanical energy is lost due to friction. Then the train goes down again, and up, and so on. However, not all coasters run this way. The train may be set into motion by a launch mechanism (flywheel launch, linear induction motors, linear synchronous motors, hydraulic launch, compressed air launch, drive tire, etc.). Some coasters move back and forth along the same section of track; these rollercoasters are called shuttles because of this motion and usually run the circuit once with riders moving fowards and then backwards through the same course. And there are even roller coasters which are powered by a kind of locomotive.

A properly designed roller coaster under good conditions will have enough kinetic, or moving, energy to complete the entire course, at the end of which brakes bring the train to a complete stop and it is pushed into the station. A brake run at the end of the circuit is the most common method of bringing the roller coaster ride to a stop.

### Blocking

Some roller coasters have the ability to run two or more trains at once. These rides use a block system, which prevents the trains from colliding. Block systems work by having the track divided into multiple sections or blocks. Only one train is permitted to be in a block at once. At the end of each block, there is a section of track where a train can be stopped if necessary. This can be done multiple ways, including holding it in the station, stopping the lift, or using brakes in the middle or end of the circuit. Sensors at the end of each block detect when a train passes, so the computer running the ride can tell which blocks are occupied. When the computer detects a train about to travel into an occupied block, it uses whatever method is available to keep it from entering. This can cause a cascade effect when multiple trains become stopped at the end of each block.

In order to prevent these kinds of problems, ride operators follow set procedures regarding when to release a newly-loaded train from the station. One common pattern, used on rides with 2 trains, is to hold train #1, which has just finished the ride, right outside the station, release train #2 (which has loaded while #1 was running), then allow #1 into the station to unload.

## History

The earliest rollercoasters decended from Russian winter sled rides held on specially constructed hills of ice, especially around St Petersburg. By the late 1700's their popularity was such that entrepreneurs elsewhere began copying the idea, using wheeled cars built on tracks. One such company was 'Les Montagues Russes a Belleville' which constructed and operated a gravity track in Paris from 1812. The first loop track was probably also built in Paris from an English design in 1846, with a single-person wheeled sled running through a 13-foot diameter loop. None of these tracks were complete circuits.

The first roller coasters in the USA were based on gravity switchback trains developed in the 1880s. These primitive coasters were run to provide amusement by railroad companies on weekends when ridership was lower. The earliest complete circuit track appeared in 1884, and in 1885 Phillip Hinkle introduced the concept of the "lift hill." By 1912, the first underfriction coaster was developed by John Miller, often called the Thomas Edison of roller coasters. Soon, roller coasters spread to amusement parks all around the United States and the rest of the world. Perhaps the most well known historical roller coaster, The Cyclone, was opened at Coney Island in Brooklyn, New York in 1927. Like The Cyclone, all early roller coasters were made of wood. Many old wooden roller coasters are still operational, at parks such as Kennywood near Pittsburgh, Pennsylvania and Blackpool Pleasure Beach, England, UK.

The Great Depression marked the end of the first golden age of roller coasters. Theme parks in general went into a decline that lasted until 1972, when the Racer was built at Kings Island in Mason, Ohio (near Cincinnati). Designed by John Allen, the instant success of the Racer began a second golden age, which continues through this writing 2003.

In 1959, the recently-opened Disneyland theme park introduced a new design breakthrough in roller coasters with the Matterhorn Bobsleds. This was the first roller coaster to use a tubular steel track. Unlike conventional wooden rails, tubular steel can be bent in any direction, which allows designers to incorporate loops, corkscrews, and many other manoeuvres into their designs. Most modern roller coasters are made of steel but wooden roller coasters are still being built.

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Top Thrill Dragster, the world's second tallest and second fastest roller coaster, second only to Six Flags Great Adventure's Kingda Ka

Some of the major variations in contemporary roller coaster design involve the modification of the car. Some seat the passenger in a bodyless frame, with the passenger's legs dangling in the air and providing a less-obstructed view of the ground, thus providing an extra scare to the passengers. Another variation involves cars that have the riders in a standing position (though still heavily strapped in). Finally, some rollercoasters spend some or all of their travel time with the passengers sitting in the opposite direction to their travel, so they cannot see what direction the coaster will travel next.

In 1992, the first inverted track roller coaster, Batman The Ride, opened at Six Flags Great America in Gurnee, Illinois. As of 2005, the roller coaster holding the records for greatest speed and height is Kingda Ka at Six Flags Great Adventure with a top speed of 128 mph (193.2 km/h) and a 456 foot (128.1 m) vertical hill. New roller coaster designs and state of the art technology push the physical limits on what type of experiences can be had on the newest coasters. For example, coasters like the Incredible Hulk Coaster feature launch lift hills to create an unique experience.

## Safety

Because roller-coasters are intended to feel risky, accidents, such as the September 5, 2003 fatality at the seemingly tame Disneyland Big Thunder Mountain, attract public attention.

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Riding Expedition GeForce

Statistically, roller coasters are very safe. The U.S. Consumer Product Safety Commission estimates that 134 park guests required hospitalization in 2001 and that fatalities related to amusement rides average two per year. According to a study commissioned by Six Flags, 319 million people visited parks in 2001. The study concluded that a visitor has a one in one-and-a-half billion chance of being fatally injured, and that the injury rates for children's wagons, golf, and folding lawn chairs are higher than for amusement rides. In fact, driving to the amusement park has a higher risk of injury than riding the rides at the amusement park.

Nevertheless, accidents do occur. Regulations vary from authority to authority. Thus in the USA, California requires amusement parks to report any ride-related accident that requires an emergency room visit, while Florida exempts parks whose parent companies employ more than 1000 people from having to report any accidents at all. Rep. Ed Markey of Massachusetts has introduced legislation that would give oversight of rides to the Consumer Product Safety Commission (CPSC).

In 1999, a rider who weighed more than 400 pounds (180 kg) was unable to close his lap bar properly and was thrown from the Superman coaster at Six Flags Darien Lake, sustaining serious injuries. Despite this, a similar accident occurred in 2004 when a 230 pound (100 kg) man with cerebral palsy was permitted to board the Superman coaster at Six Flags New England and, on the last turn of the ride, was thrown from his seat and killed. Critics maintain that, despite the generally good safety record, accidents are occurring that are preventable.

In recent years, controversy has arisen about the safety of the increasingly extreme rides. There have been suggestions that these may be subjecting passengers to translational and rotational accelerations that may be capable of causing brain injuries. In 2003 the Brain Injury Association of America (http://www.biausa.org) concluded in a report (http://www.biausa.org/Pages/blue_final_report.html) that "There is evidence that roller coaster rides pose a health risk to some people some of the time. Equally evident is that the overwhelming majority of riders will suffer no ill effects."

## Roller coaster firsts

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