When Valleying Occurs on Coasters

Walt, you weren't crazy, Waldameer has since removed all mid-ride anti-rollbacks as the ride flew through those preventative sections had them. The anti-rollbacks served as nothing but a trim as they scrubbed off a little bit of speed, while not doing really anything positive.

The rollbacks were on the top of the hill across the street, over the bunny hop by the queue, and on the final turn once you come up the hill into the final hops.

Someone already beat me to the Ravine Flyer II answer...that ride had anti-rollbacks on it, but they have been removed (other than the lift hill).

On Intamin's hydraulic-launch coasters, the launch pin is counterweighted so that it retracts into the car body when the car releases from the launch sled. If the train fails to make the hill, it will roll backward down the hill, but it will not reengage with the launch sled because the launch pin is retracted. During or immediately after the launch sequence, the brake fins are raised on the launch track. That way, if the train comes back down the hill, it will be slowed to a crawl by the brake fins on the launch track. The train can be allowed to roll back all the way to the launch point because the block system will not allow another train to stage for launch until the one ahead clears the top of the hill. This is similar to the system used on the Premier LIM launched coasters.

The LSM-launched coasters are a bit simpler because if you kill the power to an LSM, because there are active magnets on the train (not just passive fins as with a LIM) the "dead" LSM stator coils behave like brake fins against the permanent magnets on the train. This slows the train's progress backward down the hill until it reaches the brake wheels at the launch staging point. Again, the blocking system is designed to accommodate this possible scenario by not allowing another train to stage until the point of no return is passed.

The absence of an anti-rollback is not by itself a Bad Thing™. The challenge is to determine what Bad Things™ can happen as a result of a rollback and make sure that some means is built into the system to prevent those Bad Things™ from happening. On some rides, the ability of the train to go backward is actually a convenient simplification, as it allows launched coasters to be safely (and almost automatically!) reset without too much effort.

--Dave Althoff, Jr.