Top Thrill 2 4/28/2024

I've typed up a similar response 5 different ways. It's not so much about making sure it's locked because as has been said we know this because it has a green light. But what we don't know is if a skinny teenager or their large parent is in the seat.

Chris R:

If we were fast enough, we could have that train come right into unload without parking.

There's a YouTube video that breaks down the current issues with Millennium Force that points out that it's not completely the safety process's fault. Even if the crew crushes it and hits the interval they have to wait for the catch car to come down the lift and engage with the train. The catch car is just slower than it used to be.

Jeff:

To your own point, if the machine gives you a green light, the way the operator checks it doesn't matter. The machine said it's good.

That is not my point. My point is that the operator check is needed because the machine doesn't know what "good" is; all it knows is that the restraint reached or didn't reach the point that it would trigger the position sensor. The computer doesn't know, nor can it know, what kind of person is in the seat. The operator does know this.

Explain to me how the rider pushing up, with the operator seeing it, is different from the operator doing the same thing and seeing it.

I'm not going to explain it, because I don't care about this part. In fact, I conceded this point in my previous post. The operator pulling up on the bar does nothing. Fully agree. What I'm saying is that for certain rides, the operator checking the restraint is more about ensuring that it is in the fully down position with respect to each individual rider and their body type.

...the machine won't even let you dispatch if the restraint isn't in the right position (you said this yourself)

Umm...no I didn't. Seriously, I'm confused by this. If you don't mind, please quote where I said this, or something similar.

To reiterate, the machine doesn't know what's "right." In this context, to the ride's designer, manufacturer, or operator, "right" means the restraint position that safely secures the rider. The ride manufacturer sets the restraint's go position for the height at which the largest allowable rider will be safely secured, but on some rides that position may not safely secure the smallest allowable rider (in part because of the ride's dynamic profile). That is, after all, why the restraint is adjustable beyond the go point.

...given that I'm not a human factors expert

I had to pretend to be one for a few months while working on InvadR. So a little sidebar that's sort of related: GCI, from the very beginning, used a reach envelope that was drawn with a rider seated fully upright. This is sensible because what you're most concerned about is overhead clearance, so someone seated upright and reaching straight upward captures the worst case scenario for overhead clearance. For side clearance, we would simply rotate the arm to a horizontal position, but still with the rider fully upright. You then draw the arc between the two arm positions, and an offset (6" if I remember correctly) and you have your clearance envelope, which looks like a big oval with two riders side by side.

Well, BGW didn't like this. They thought that for side clearance, the rider should be drawn leaning as far to the side as they could and reaching over as far as they could. I suppose this makes sense, but really the only thing you could conceivably touch is the handrail, and that is not something that anyone had every really worried about. But BGW didn't want a rider to be able to touch any part of the structure while the ride was in motion. So I found myself pouring over CDC growth charts trying to figure out how to draw a 99th percentile rider leaning to the side, and when we did this our drawings showed that the fingers were in fact in interference with the handrail. So BGW made us move the handrail out by a few inches and bevel the top of the post where the handrail mounts to provide clearance. It was a pain in the butt, and to my knowledge is the only GCI coaster, and probably the only wooden coaster period, that is like this. But hey, the customer is always right.

...but Intamin rider-tossing trains aside

Cedar Point has one of these.

If knees are above your butt, and the bar is below your knees, geometry dictates that you're not going anywhere.

Again, the machine doesn't know if the bar is below the person's knees.

And by the way, this doesn't even take into account the silly "you check only these seats" and "stand on this circle" and "don't forget to scan every seat as it leaves!" nonsense.

Fully agree, but this is not what I'm talking about.

As opposed to the rider doing it?

Yes, because riders can't be trusted to make sure their restraint is fully down.

...you're saying that who touches the restraint matters. I'm saying that it does not, in a world where the machine decides and geometry dictates what is possible in terms of rider escape.

And we've seen numerous examples over the years where this marriage between restraint geometry design and computer control has failed, resulting in someone's death.

We can argue the details all day, but what I will never agree with is your statement that ride dynamics are irrelevant to the method of restraint checking, and that what's good for Disney ought to be good for Cedar Point and everyone else. Hogwash, I say! If I was the head of park operations at Cedar Point and I was being pressured to implement the Disney method, in order to cut staffing costs or increase throughput or whatever, I would resign, and I wouldn't think twice about it, because I know my park has three coasters (Millennium Force, Steel Vengeance and Blue Streak) that have aggressive ride profiles and share the same ride/vehicle designers/manufacturers as rides that have fatally thrown people from the car.

If you're trying to break it down phrase by phrase, I don't think you're seeing my logical argument at all. But I'll play along I guess.

Bakeman31092:

The computer doesn't know, nor can it know, what kind of person is in the seat... Again, the machine doesn't know if the bar is below the person's knees.

Because in modern restraint design, it doesn't have to know what kind of person is in the seat. The geometry of the seat covers a certain range of heights, and that shape will hold a person at the go point. The geometry by default marks the go point when the bar is below the knees if the rider is between the minimum and maximum heights. The tightness and firmness doesn't matter, you can't get out. A ride operator standing over the restraint couldn't possibly make that determination by looking (pushing doesn't confirm anything but touching, not where the restraint is relative to the dispatch point), and they certainly can't be expected to be human factors experts.

If you can tell me how the rider checking the geometrically correct restraint, with verification by the machine, is less effective than the operator doing so, I would happily concede. But you haven't given any evidence of that beyond anecdotes around older rides.

The Holiday World accident is a total strawman. You're comparing a PTC train that was essentially designed 50 years ago to a modern system made of milled aluminum and carbon fiber with a double hydraulic restraint monitored by electronics. It's like comparing a Model T to a Model Y. [Insert self-driving joke here.]

The idea that I'm reacting to most strongly is that what's good for Disney ought to be good for everyone else, because ride dynamics are irrelevant to restraint checking. I fundamentally disagree with this position, and I've tried explaining why in many different ways (as have others). So we'll have to agree to disagree on that one.

Re: modern restraints. Define "modern." Millennium Force's restraint system is 24 years old at this point. I think each restraint design needs to be considered individually, because it has been demonstrated, tragically, that some designs are better than others. I may be willing to grant that B&M's clamshell lap bar could probably get away without having a human check of any kind, because of the way it is shaped and configured. It should be noted that the minimum height requirement for the clamshell restraint rides is 54", so they are raising the floor for the size of the smallest allowable rider, which reduces the amount of variation they have to deal with. But not all restraint systems are that good.

The Raven incident is not a strawman. I linked to it within a sentence where I was saying that you can't trust riders to put the bar where it needs to be to safely secure them, and to prove that you can be tossed from a PTC that the ratchet clicks and the sensors (if they have them) said was "good." There's nothing strawman about that.

Direct question that I'd like for you to answer: why are coaster restraints adjustable beyond the go point? Correct me if I'm wrong, but according to your logic once a restraint hits the go point, the full range of riders that can fit into that seat will be safely secured because geometry. If so, then why does the restraint designer add all that complexity (read: cost) to make it adjustable across a wider range?

That's easy enough... comfort. I imagine TT2 would hurt if you had a lot of travel between you and the restraint. It's why I always say that Magnum is best with a tight belt. It doesn't make you more secure, but it does make it more comfortable.

And what's modern? I'd say probably anything made in the last five or six years, certainly RMC's design, the newer iterations from Intamin (Velocicoaster), the "pull-over" B&M's, Zamperla's Lightning train. These all share a number of characteristics, including deeper seats, crotch bumps, no belts, double hydraulic locks and the aforementioned geometry.

I still don't see why ride dynamics dictate the way they should check restraints. Remember inversions "required" horse collars, and speed and height "required" belts. We seem to have finally gotten passed that. Here's the thing you said that I don't agree with:

There's no way you could have a lap bar self-check policy on something like Steel Vengeance, because I know there are people that if they were allowed to would keep the lap bar as loose as possible, and that would spell disaster on a ride that is trying to toss you out at every turn and hill.

This sentiment makes several assumptions:

• The machine doesn't require minimum closure (the RMC trains do).
• The geometry would allow someone to get out at the minimum closure (I'd like to see anyone try next IAAPA).

I thought there were more, but I guess it's that simple. The only exception that I can think of is that they allow someone who is too short ride. Otherwise, if the light is green, it doesn't matter who is tugging on the restraint. I would be perfectly comfortable putting someone I love on TT2 if the ops only watched them push up on the bar. The only way they're coming out is if they break several bones in their legs.

Jeff:

Because in modern restraint design, it doesn't have to know what kind of person is in the seat. The geometry of the seat covers a certain range of heights, and that shape will hold a person at the go point. The geometry by default marks the go point when the bar is below the knees if the rider is between the minimum and maximum heights. The tightness and firmness doesn't matter, you can't get out.

I' pretty certain I could get out of a MT seat with the restraint far enough down to show green, and I'm a foot taller than minimum rider height. I know GCI has since updated their restraints but this ride isn't even 10 years old.

Jeff:
If you can tell me how the rider checking the geometrically correct restraint, with verification by the machine, is less effective than the operator doing so, I would happily concede.

I want airtime and will leave it loose. The op (usually) will not.