Posted Friday, November 18, 2005 6:33 PM | Contributed by coasterpunk
A power outage Tuesday night stranded half a dozen people on the Stratosphere's X-Scream ride in mid-air hanging off the tower. Stratosphere officials say they were about to resort to manual hydraulics to bring the ride back to its dock despite having backup power. Instead, Nevada Power managed to restore service and that's when the ride returned automatically and the passengers were finally able to get off.
Read more from KLAS/Las Vegas.
This just screams of someone not counting on Vegas losing power. The grid there is actually pretty stable but still every casino has it's own backup generators. I don't understand why the Strat's backup system or the backup system that has been used for the top of the tower before couldn't handle the problem.
However most rides, and from what I read assume that X-scream, a power outage results in all brakes being closed, and is like e-stopping the ride. The only major difference with a ride on top of the tower is that when it has a power failure or estop and riders must be evacuated, it is much more difficult.
Just the fact that the riders are up around 1000 feet or so in the air, and they are more nervous and scared compared to a normal downtime situation on a roller coaster or ride on flat land. Also couple that with the actual difficulty of actually evacuating riders, when they are over the edge without power, results in that the best scenario was to get power back to the ride in any fashion.
They were about to use manual hydraulics in place in the ride system, to move the riders back to the loading position, to be easily removed from the ride. The only issue really was the fact that the backup power system in place, was not able to restore power to the ride, to ensure easy and quick evacuation of the ride. That portion of the grid losing power, is not a frequent occurance, but can be expected to happen in rare occasions.
And is the reason they have the backup power supply. In this case, I am sure they are having their engineers determine why the backup power supply did not work as expected. Once they figure that out, I am sure the ride will open back up. Although the actual situation is very bad from a publics relations view, it is not that unsafe. It is something they would rather avoid, and not deal with, especially the news coverage and the perception. So determing a way to not have them stranded out there for that long, is something they will fix before it opens. A power failure is not unavoidable and has nothing to do with them, but an adequate backup power supply is something they can control.
Second, the word manual in "manual hydraulics" would indicate that the hydraulics in question could be operated without power, a fact that would have been confirmed if you actually had read the news story. The fact that the backup power could not run the ride had nothing to do with them not using the manual hydraulics--the article says that they were about to retrieve the vehicle with the manual hydraulics, but power was restored and they opted to reset the ride normally.
However, the fact is, is that I don't know the exact details of what caused the power outage, or how often they occur in las vegas. If I have time I could likely research it. But it is not unreasonable to think that this could occur every one in a while, maybe once every 2 years or more. So having a better and more efficient way of evacuating the ride, and reducing the negative press and perception is something that could be improved.
Also read my post entirely, I never once said that the manual hydraulics had to do with the backup power not being there. But they wouldn't go to use it, if the backup generator was working properly. That is what is likely being investigated. There would be really no other reason to have the ride closed now. It appears everything else was working fine.
I mentioned my previous experience as a ride operator, since I do have something to go back on regarding downtime, evacuating rides, and what do when a power outage happens.
Assuming the power goes off and stays off...
Now, if the Flying Scooter loses power, the ride coasts to a stop and everybody gets off.
If The Beast loses power, the trains will roll to a stop on either the next block brake or the next lift, as appropriate. You then E-stop and lock-out the ride, then go out to wherever the trains are with the necessary tools, you pop all the lap bars open, you walk the people down to the nearest evacuation point, and return them to the park. (I know, there is more to it than that, but you get the idea).
If the Troika loses power, things can be a little more complicated. On that one, I assume the hydraulics, being gravity-loaded, will simply allow the arms to drop so that the people can be let off. But I may be wrong about that. Instead, it may be necessary to manually open a valve under each arm in order to get the arms down. My guess is that as a ride operator, you knew exactly what would happen if the power went out, where the keys for the lap bars were kept, where the release pins are located on the vehicles, and in the case of the Troika, exactly what would happen if the ride were up when the power failed, and probably where the emergency release valve is located. You might not have been empowered to open that valve, but you would have known where it was and how to operate it. Why? Because that is the kind of thing that ride operators are expected, in fact required, to know. The ride operator is expected to know exactly what needs to happen when the power goes out, and the extent of those things he is permitted and/or qualified to do towards evacuating the ride.
In Vegas, the ride is in its tipped down position, and the magnetic brakes and the mechanical stop are holding the car, and the lap bars are holding the riders. Because the car is at the bottom end of the ride, bringing it home without power is a bit of a problem because gravity is working against bringing the ride back down. If they were to manually open a hydraulic valve, the best that could happen would be for the arm to release so that it could be moved manually, but it would not come back down to the load position unless someone could provide the force to drop the arm. Perhaps a come-along tied to the bottom of the load end of the boom or something like that. In practice, the ride is supposed to have a battery-operated hydraulic pump that will bring the thing back down in case of a power failure. My guess is that this system is the "manual hydraulic" system they were able to avoid using when the power came back on.
--Dave Althoff, Jr.
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