I don't 'get' TTD or Kingda Ka

[gerstlaueringvar]

But when a train stalls at the top, the park would need to make sure if there is anything on the track that's stopping the train or the train stopped because of the lack of speed. They can't simply put a friction wheel at the top of the top hat and push the train when it stopped.

[Moose]

Sure they could. It's a nature of that ride that causes it to be designed to just make it over the hill that every once in a while it won't make it. If it made it up the hill that far I doubt there could be anything in a wheel.

[gerstlaueringvar]

^ You never know when it's going to happen. Safety first.