Understanding a Roller Coaster's |
A Roller Coaster requires a sophisticated monitoring system in order to run more than one train at a time. With only one train on the active track, it is impossible to have a collision with another train. When there are multiple trains on the active coaster track, this is when the monitoring system shows its true usefulness. In order to prevent trains from getting too close to each other, a protective system called a "Block System" is in place. In order to understand a block system, think of the track as a flat image, like the photograph below (diagram 1) of one coaster control panel which shows a diagram of the layout of the entire track. To have a block system, first you need to establish a series of "blocks," or areas of the track in which a train will operate. |
Diagram 1 |
Each group
of 3 lights represents a train in that block or area. |
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Each block must have the following two elements. First, it must have a means of stopping
the train prior to the end of that block. This could be in the form of either gravity,
such as the train stopping on the disabled lift chain, or in the form of a mechanical
brake. Second, it must have some means of propulsion to move the train once it has
been stopped. This could be accomplished in a number of ways. This could be
done by re-starting the lift chain, mechanical propulsion on a flat surface such as a
series of drive tires under the train, or in an area of the track that is sloped in a way
that would cause the train to roll due to gravity after the brake is released. The principle behind a block system is that when one train occupies any given block, the computer will recognize this, and will not allow a second train to enter the same block until it has been cleared. A typical coaster will be divided into at least 4 primary blocks: |
1- The section from the beginning of the
Station to the very bottom of the "Lift Hill." |
Some coasters have such a long track that it is safe to run two trains on the high speed portion of track by placing an intermediate brake, or "Trim Brake" on a straight section of the track that is designed to accommodate the forces caused by stopping a 15,000+ pound train in a short distance. Some of these trim brakes may never get used unless the computer senses that the trains are getting too close, at which time it will hold the train until it is cleared to proceed. Some coasters may also use these trim brakes during normal operation in order to maintain a safe operating speed by applying a small amount of braking as the train passes through without actually stopping it. |
Diagram 2 |
| Diagram 2 LEGEND | |
RED is BLOCK 1 |
S to
S is the loading Station A to A is the Approach to the lift hill L to L is the Lift hill T is the high speed Track R to R is the Reduction brake H to H is a Holding brake |
The computer detects the presence of a train in any of a number of ways. The most popular are by using Proximity Switches (diagram 3) which are electromagnetic devices positioned at precise locations on the track. These switches detect the presence of a metal object, such as a metal "flag" mounted on the bottom of the front and back of the train. The flag on the front of the train is used to tell the computer that the beginning of the train has entered a given block, whereas the flag on the (opposite side of) the rear of the train would tell the computer that the back of the train has cleared a particular block. This system leaves little margin for error. |
Diagram 3 |
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Another device used for train detection is a photo eye. (Diagram 4) A photo eye can
function in a few ways. One way is to have a pair of photo eyes mounted directly
across from each other which project a constant beam of light back and forth. Another
would be a single photo eye that bounces a beam of light to a stationary reflector mounted
on the structure. In either case, when the train disrupts the beam of light, it indicates
to the control system that a train has entered the block. The last use of a photo eye
would be with a structure-mounted photo eye and a reflective tape strip adhered to the
side of the actual train. In this scenario, the train is what reflects the beam to the
photo eye instead of breaking the beam. Some parks aren't real fond of this method,
because if a mechanic or carpenter is walking on the catwalk and forgets to step over the
imaginary line of light, then it will usually stop the trains and will then need to be
reset. |
Diagram 4 |
| The last (and
least popular) way to detect a train is by using a mechanical "limit
switch." (Diagram 5) This switch is also mounted on the track, but has a moving arm that actually comes in contact with the train as it passes. The switch is spring loaded, so as the train passes over, it pushes the switch forward, showing the position of the train, and then when the train has passed, the switch lever returns to the normal position. |
Diagram 5 |
| With all three of the
above signaling devices, you will almost always see these devices used in pairs. In
other words, there will be two switches mounted in a row so that if one should fail, there
will still be a working backup device. There are other uses for these switches. Sometimes they can be used to compute the speed of the train, indicate if all of the passenger restraints are properly locked, or even to activate various novelty items such as a spray of water, strobe lights in a tunnel or even a fog machine. In any case, now that you understand what a block safety system is and how it works, you have no reason to get all worked up if your train stops at the top of the hill or on a trim brake. If your train stops at the top of the hill, it simply means that there's either a train that has not yet cleared the reduction brake, or else a switch has failed, in which case the system has worked properly by halting operation until it can be manually verified as safe by a mechanic. Many roller coaster and amusement rides are caused by Operator Error. Click HERE to learn more about operator error and what you as a patron can do to help prevent incidents and accidents. Despite the enormous effort that both parks and many other major corporations put into hiring, training, and monitoring their employees for safety and customer service, ultimately, one can not reasonably expect that they can keep a new employee from fooling around at the job site.
See also: |
