I'm really not a fan of the whole Robotic Arm idea. Whilst visually they look awesome- I totally have a vision of them being arranged in a circle around a dramatic centre-piece (calling it a tree sounded pathetic, but yeah... a tree) and the arms act as the roots and branches of the tree...
Back to reality though, let's look at the operational aspects to this. For argument's sake, lets say each robotic arm held four people. Using the suggestions above of 5 robotic arms, that equates to 20 guests per ride cycle.
Now, the more arms you have, the more complicated the loading procedures get for the attraction. If we say, on a realistic basis, that it takes five minutes to load, complete it's ride cycle, unload and then load again, then that's about 12 ride cycles each hour. That would give us an hourly throughput of 240 people.
For a park like Alton, those kinds of throughputs just aren't acceptable; they should really be aiming for throughputs closer to the 1000 mark on their attractions, and of course, over that on their major ones.
Even if you had 10 robotic arms, if you use the same figures as above, that's still only an hourly throughput of 480 people. For reference; Rameses Revenge gets around that per hour.
What I'm trying to say is, it'd be an operations nightmare! :P
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