From the Functional Design Plans, you can see the four transition points identified as follows:
TS = Tangent to Spiral. This is when the track moves from being straight, into the spiral (decreasing radius curve).
SC = Spiral to Curve. This is the transition point between the variable-radius spiral, to the constant-radius curve section.
CS = Curve to Spiral. Opposite of above.
ST = Spiral to Tangent. Opposite of above.
(When the system was being built I kept seeing these marks on the pre-rolled curved sections when they were delivered, so I dug a little deeper.
)
Without using a transition spiral, there is a hard jerk. The analogy would be driving a car at some fixed speed and then suddenly jerking the wheel by turning it instantly say 90 degrees one way or another. Once you're in the curve, holding the wheel... it's smooth because it's a fixed lateral acceleration that you are feeling. But the rate of CHANGE was instantaneous - you jerking the wheel. That's like going from straight to a fixed radius curve.
Spiral curves are the automotive equivalent of gently turning the wheel. The lateral acceleration (force) is applied gradually, so it feels smooth.
Steel roller coaster engineering took a good 2 decades to figure this out. All original Arrow Dynamics steel coasters had horrible, fixed-radius curves which result in slamming and banging and a very jerky ride. While the trains themselves would ride smoothly on the rails, any time the track went from straight to curved, you'd slam your head against the restraints. Probably the most violent example of this still around today is the Magnum XL-200 at Cedar Point - the return run back to the station is just brutal. I laugh every time I see it.
TS = Tangent to Spiral. This is when the track moves from being straight, into the spiral (decreasing radius curve).
SC = Spiral to Curve. This is the transition point between the variable-radius spiral, to the constant-radius curve section.
CS = Curve to Spiral. Opposite of above.
ST = Spiral to Tangent. Opposite of above.
(When the system was being built I kept seeing these marks on the pre-rolled curved sections when they were delivered, so I dug a little deeper.
)Without using a transition spiral, there is a hard jerk. The analogy would be driving a car at some fixed speed and then suddenly jerking the wheel by turning it instantly say 90 degrees one way or another. Once you're in the curve, holding the wheel... it's smooth because it's a fixed lateral acceleration that you are feeling. But the rate of CHANGE was instantaneous - you jerking the wheel. That's like going from straight to a fixed radius curve.
Spiral curves are the automotive equivalent of gently turning the wheel. The lateral acceleration (force) is applied gradually, so it feels smooth.
Steel roller coaster engineering took a good 2 decades to figure this out. All original Arrow Dynamics steel coasters had horrible, fixed-radius curves which result in slamming and banging and a very jerky ride. While the trains themselves would ride smoothly on the rails, any time the track went from straight to curved, you'd slam your head against the restraints. Probably the most violent example of this still around today is the Magnum XL-200 at Cedar Point - the return run back to the station is just brutal. I laugh every time I see it.