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Safety Mechanisms and technology
A variety of safety mechanisms protect riders on roller coasters. One of these is the block system. Most large roller coasters have the ability to run two or more trains at once, and the block system prevents these trains from colliding. In this system, the track is divided into two or more sections known as blocks. Only one train is permitted in each block at any given time. There is a section of track at the end of each block where a train can be stopped if necessary, such as preventing dispatch from the station, stopping a lift, or simply applying brakes. Sensors detect when a train passes so that the system's computer is aware of which blocks are occupied. If a train attempts to enter an occupied block, the stopping mechanisms in all blocks are engaged. Restraints are another critical aspect to roller coaster safety.

Generally speaking, roller coasters usually have two different types: Over-the-shoulder-Restraints and lap bar restraints. With both,. Hydraulic and mechanical  safety mechanisms are used within the restraints. Mechanical restraints use a system known as a ratchet and pawl. When riding a roller coaster with a ratchet and pawl system, the sound of clicks can be heard when pulling down the restraint. Hydraulic restraints use a piston and cylinder. Unlike mechanical restraints, there is no feeling of physical or sound of clicks from the restraint being locked in place. Most modern day roller coasters have sensors that are used to make sure each restraint is locked. If all the restraints are locked, it will send a signal to the ride computer letting it know that it is clear for dispatch. If all restraints are not locked, the train will not be able to move out of the station until each restraint is locked.

Breaking systems such pivoting paws are used on the bottom of the train and on the inclined lift hill. While the cart goes up the lift hill, it is usually pulled by a chain. The pawl moves over bumps that are separated closely apart. In the event that the train ever becomes disconnected from the chain, the anti roll-back system will engage and it will fall back into the nearest downhill stop preventing the train from falling down the lift hill.

Another key to safety is the programmable logic controller (PLC), an essential component of a roller coaster's computer system. Multiple PLCs work together to detect faults associated with operation and automate decisions to engage various elements (e.g. lift, brakes, etc.). Periodic maintenance and visual inspection by ride engineers are also important to verify that structures and materials are within expected wear tolerances and functioning correctly. Effective operating procedures further enhance safety as well.

Roller coaster design & statistics
Roller coaster design is another important aspect that requires a working knowledge of 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. Designers typically try to stay in the range of 4–6Gs (40–60 m s−2) 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 1.5–2Gs (15–20 m s−2) as a maximum.[citation needed] These fall into a range considered safe to a majority of the population. Lateral acceleration is also typically kept under 2Gs using various techniques including the banking of curves.[citation needed]

Wheels are a critical part in rollercoaster design. The purpose of wheels is the 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 3 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 so that the train can move through turns without flying off the side of the track. Up-stop wheels are the wheels that ride below the track and prevent it from lifting off the track.

Roller coasters are statistically very safe when compared to other activities, but despite all the safety measures in place, accidents still occur. The International Association of Amusement Parks and Attractions (IAPPA), reports that 1 in 15.5 million has the chance 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". IAPPA is required to report annual ride incidents to the National Safety Council.