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TusenFryd | Storm | Gerstlauer Invert | 2023

Hixee

Flojector
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Quality insight there, @Indy - thanks.
As you can clearly see in this photo, there are no bolt holes which is pretty wild. It seems that they literally pour a giant pocketed footer and set the support down into it with no anchor rods whatsoever. They rely completely on the concrete to hold the support in place. So, they probably have all of those supports strapped to some sort of anchor to provide stability until the concrete has been poured and cured. It is a pretty strange approach.
That might explain why Gerst's supports are always so over the top - none of it is actually very secure. :D

EDIT: Re-reading this bit:
Typically, the base plate that the shear key is welded to would also have large bolt holes. Anchor rods are usually set in a concrete footer and you thread the anchor rods through the bolt holes when lowering the support into place. Then, you take large washers and nuts and tighten the support to the anchor rods. Once construction of the entire ride is complete, you fill in the pocket where the shear key rests with cementitious grout and then torque the nuts. Done.
Any chance they're doing that welding on site?
 

Rupert

Mega Poster
Indeed thanks @Indy for the informative post. I’d thought I’d read in the past that Gerstlauer don’t bolt their supports down at all even below the poured concrete, just relying on the concrete itself to hold them in place. I’d never seen the shear plate though - does its existence mean there has to be a base plate welded beneath it to transfer stress to, or can it sit directly on top of concrete?

That might explain why Gerst's supports are always so over the top - none of it is actually very secure. :D
Agreed, and also explains why Gerstache is such a thing! The bottom of Saw’s first drop for example - I’d always assumed the supports had come slightly loose from the concrete they’re contained in which gives the strong jolt as cars pass over it, allegedly made worse by slight subsidence here in the watery ground. Not sure how accurate that is but in all cases you’d assume tracks would give a smoother ride if fully bolted down, rather than relying on concrete adhering the supports in place.

Apologies if I’ve misinterpreted Indy’s post or got this all wrong. It seems so mad that one manufacturer has a completely different process from all the others (as well as being the one with more of a reputation for roughness).
 

Indy

Mega Poster
I’d never seen the shear plate though - does its existence mean there has to be a base plate welded beneath it to transfer stress to, or can it sit directly on top of concrete?
I'm not sure I understand the question so I'm going to go further in depth in hopes of explaining it better. Below are some photos that I've found from WKRC News in Cincinnati from when Orion was built and they help explain the process.

First, when I refer to a base plate, I simply mean the plate that is welded at the bottom of all tubular supports. Sometimes they have the shear key welded to them and sometimes they don't.

When building a coaster, typically what happens is you pour footers with anchor rods in them and pockets in the center to accommodate a shear key during initial construction. Below is a perfect example of this:

1663251642290.png
You can clearly see the footer, the six anchor rods with nuts already on them, and a pocket for a shear key. When you get ready to place a support, you twist those nuts down and survey them to make sure they are at the right height. Then you place the support on top of them and take six additional nuts (and plate washers) and tighten the support in place. For the remainder of the structural construction, the base plate/support will sit there fully supported by the nuts/plates/anchor rods. Below is a good photo of this:

1663251975774.png

You can clearly see a gap between the base plate and the footer. You can also see the shear key going down into the pocket. You leave this gap and pocket open until the structure is complete. That allows the structure to find the place it wants to "live." Then, you go to each footer and you fill in this gap and pocket with grout.

Below, I've zoomed into a footer in a photo I took of Fenix (no, I didn't take a photo of just the footer 😆). You can see the grout that was poured to fill the gap between the base plate and the footer. This essentially locks the shear key into place. So rather than the anchor bolts absorbing lateral/torsional load, the foundation absorbs it via the shear key. The anchor bolts keep the support from lifting. The footer keeps the support from sinking. The shear key keeps the support from sliding or twisting.

1663252591096.jpeg

So, that's an explanation of the more common process. Obviously, Gerstlauer doesn't do it that way. I really have no idea what their base plates rest on down within those hollow footers that they've poured. I would think that there has to be some sort of steel ring that is set within the concrete and surveyed so that they know the support is at the right height, but I really don't know what their exact process is. I'm a bit perplexed.

The bottom of Saw’s first drop for example - I’d always assumed the supports had come slightly loose from the concrete they’re contained in which gives the strong jolt as cars pass over it, allegedly made worse by slight subsidence here in the watery ground. Not sure how accurate that is but in all cases you’d assume tracks would give a smoother ride if fully bolted down, rather than relying on concrete adhering the supports in place.

I haven't ridden Saw, but it's not outside of the realm of possibility that the support is coming loose and that's not a problem that is specific to Gerstlauer. It can happen with coasters that have track bolted directly to the footer, such as the case when you have a section of track that drops essentially all the way to the ground on a first drop. A connection plate on the track will often be bolted directly to the footer without any sort of support column in between. A structural support helps absorb vibration. However, without a support between the track and footer, the repeated vibration and beating the track takes from the train passing over gets passed directly into the footer and can deteriorate the bond between the anchor rods and the concrete over time.

It seems so mad that one manufacturer has a completely different process from all the others (as well as being the one with more of a reputation for roughness).

It is certainly strange, but every manufacturer designs and builds rides a little differently and they all have their reasons for their approaches. I'm sure there is a decent reason for Gerstlauer's approach.

That being said, there are also a number of reasons why a steel coaster can be rough. Track manufacturing is often a huge factor as are the trains/wheel assemblies. The actual assembly of the track on site can be a huge factor too. If you don't have completely smooth and seamless connections between the rails, then it can lead to a rough ride. That's why a lot of times you can spot places on brand new coasters where the paint has been removed from the rails near a connection point; they've been grinding on the rails to smooth out the transition between pieces.
 

Rupert

Mega Poster
You can see the grout that was poured to fill the gap between the base plate and the footer. This essentially locks the shear key into place. So rather than the anchor bolts absorbing lateral/torsional load, the foundation absorbs it via the shear key. The anchor bolts keep the support from lifting. The footer keeps the support from sinking. The shear key keeps the support from sliding or twisting.
This (and indeed the whole post) is fantastically clear and interesting - thank you!
 

Indy

Mega Poster
Any chance they're doing that welding on site?
Definitely not. Shear keys will be part of the engineering design process. They affect the base plate design and also the foundation design. You always want to avoid welding on site if possible because it's just a lot harder than in the fabrication facility. Plus, you need to have welds inspected so it makes sense to do it right there in the factory.

I shudder a little when I look at these old Arrows that were all welded on site... everything! Track welded together. Track welded directly to the supports. Seems like a nightmare.
 

jasone

Roller Poster
Is that the angle the picture is taken from, or is that lead in to the dive loop pretty steep? Despite the terrible capacity issues with this coaster, it looks like it could ride pretty well. I'm intrigued to see what a gerst invert will ride like.
 

Hutch

Strata Poster
My bias against Gerstlauer is coming out, but what is going on with that shaping?

I'd love to be wrong, but I can't see this being any good between it being a Gerstlauer and having a lackluster layout.
 
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