Wooden Coaster - Construction of Track

Sunday, April 12, 2009 8:16 PM

Does anyone know the typical dimensions of the pieces of wood used to build the track on your basic wooden coaster? When I say "track", I mean the layers of board.

I read somewhere that the boards are 2"(W) by10"(L). That doesnt seem right. Seems more like 4"x10"

Anyone? GCI people help me out here lol

And what kind of thickness? 1/4"?

Last edited by DorneyDante, Sunday, April 12, 2009 8:17 PM
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Monday, April 13, 2009 12:07 AM

2x10 sounds about right, with the top two layers offset 2" to the inboard side to form the upstop flange. Nine layers means the whole track stack would be about 15-3/4" thick (remember a 2" dimensional board is only 1-3/4" thick). If you're looking at 4" thick boards, then I'm guessing you are at Kennywood and you're looking at a track stack with no overlap in the top layers, as those are Miller-style tracks where the upstop rail is a steel flange on the inboard side of the stack.

The stack might also be 2x8 for the bottom six or seven layers and 2x10 for the top layer. Others out there know a lot more about these details than I do. :)

--Dave Althoff, Jr.

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Monday, April 13, 2009 12:40 AM

Rideman, are you even human? You knowledge is always appreciated and never ceases to amaze me.

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Monday, April 13, 2009 3:59 PM

Ah thank you. So many views and no answer; not even a stupid one. Just one intelligent answer. I'm glad someone understood what I meant. Thanks rideman!

Not to split hairs but the board is not 2D if its 1-3/4" thick. I smell 3 dimensions there :p but i got what ya mean. haha thanks again

One question: Why offset the 2" board when you can just use a single 4"x10"? Wouldn't be as flexible due to the wider width im guessing?..

Sorry for the boring conversation people. hahaI like to know the technicalities of things ;) Its the architect in me

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Monday, April 13, 2009 4:10 PM

^Four-by (4" thick lumber) can get ridiculously expensive to use when you don't require that structural rigidity. Considering that we're talking track-bed and running boards instead of structural supports, 4" thick lumber just isn't needed...and as you mentioned, they're even harder to bend/shape than 2" thick boards.

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Monday, April 13, 2009 5:13 PM

When I said 4" inches, I was referring to the width of the board; not the thickness. The thickness is 1-3/4. We are past that. haha

He said its 2" wide boards but the top layer is offset and fastened from the inside? ....wow. interesting.

Back to my point. Why not just use a 4"x10" for the top layer. Wouldnt that eliminate the process of offsetting the boards and having to fasten them from the inside?

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Monday, April 13, 2009 6:00 PM

I just remembered where it was that I read about the actual construction of a wood coaster track, and it just so happens I can lay my hands on it right now...
(user gets up from his desk and runs up two flights of stairs, grabs a bound volume from a shelf, and...)

Speers, Robert R. "Physics and Roller Coasters - The Blue Streak at Cedar Point," American Journal of Physics, Vol. 59, Number 6, June 1991, pp. 528-533.

It says here...

Concrete piers form the foundation of the Blue Streak. The elevation along the track was established with dimension lumber trusses that were fabricated on the ground, rotated to the vertical onto the concrete piers, and connected with 2x6 crossbracing. Subsequently, seven layers of 2x6's were bent and laminated together over the top of trusses to form the desired profile and the base of the track. The top two 2x6's are offset toward the center of the track. A steel strap is screwed to the top of the 2x6's for the main steel wheels of the cars to ride on. Smaller "uplift stop wheels" run under the top 2x6's to prevent the cars from leaving the track. A steel strap is also screwed to the underside of the top two 2x6's in critical places to provide a hard surface for the uplift stop wheels to uplift against.

I don't know if that analysis is based on looking at drawings or if it is estimated from looking at the ride. I do know that the article goes on to do a detailed analysis of the Blue Streak using an accelerometer borrowed from the automotive industry. It runs in my mind that the newer rides are using 2x8 instead of 2x6 lumber but I don't remember why I think that.

It does make sense to offset the top two layers rather than just using a wider board. After all, you are supporting the outer edge of the top board, you are still within the wheel track, and why pay more for a larger board when you can use the narrower ones you already have on hand? That extra two inches can be really expensive!

--Dave Althoff, Jr.

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Monday, April 13, 2009 8:42 PM

DorneyDante said:
So many views and no answer; not even a stupid one. Just one intelligent answer. I'm glad someone understood what I meant. Thanks rideman!

You probably didn't get a gaggle of answers because not many people are familiar with wood coaster track specifics. I was interested in reading a good answer too.

Are you planning to build your very own wooden coaster, Dante?

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Tuesday, April 14, 2009 11:05 AM

I guess I'm getting to this discussion late, and Dave already figured it out. Typical track construction for the last 30 years or so is 5 to 7 layers of 2" x 6" board (preferably douglas fir but most likely yellow pine) with two layers of 2" x 6" on top that have been offset. This is the method that was used by PTC, Dinn, CCI, and GCII. Cobb probably did the same thing too, I'll have to study the Judge next time I'm in the park. I can't say that I've looked at every wooden coaster that closely, but I haven't noticed anyone using 2"x8"s for all the layers. I'll check things out this summer when I travel. :)

DorneyDante go back to Rollergator's post and read it again. He as trying to tell you that a 4"x10" top layer would be ridiculously expensive and much too hard to bend to form a track bed. The same would hold true for a 4"x 8" or even a 4"x 6" top layer. The reason they use 2-by lumber (which is actually 1.5" thick) is because it it is thin enough to be bent.

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Tuesday, April 14, 2009 11:47 AM

^Thanks JS....I had typed out a response last night, but decided to hit delete instead. I think there's some confusion about the order of dimensions listed for dimensional lumber... (Thickness * Width * Length, never varies except for the fourth dimension)... ;)

Edited to add: The ONLY boards thicker than 2" (well, 1-3/4") are likely going to be supports since they require high structural integrity. I've always heard stacked 2x6s, 5-7 deep, with the last 2 layers being either 2x8s, or offset 2x6s, to accommodate the steel plates (running rails).

Of course, once you've gone to prefab "engineered" lumber like the Intamins, then we go a little more into guessing and less knowledge. My theory (thus far unchallenged) is that they're using the same basic method for trackbed (stacked 2x6s), but that the top layer of track, instead of using conventional lumber, is simply milled to fit (no bending or shaping required, more exact specs, and less carpentry needed).

Last edited by rollergator, Tuesday, April 14, 2009 11:55 AM
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Tuesday, April 14, 2009 1:50 PM

This is the whole concept of why laminated lumber is used in construction. :) Back to the dimensions.

2- 2X10s (stacked) will actually measure 3" x 9 1/4"-- each one measures 1 1/2" x 9 1/4". One 4 x 10 will actually measure 3 1/2" x 9 1/4". Using the 2x10s is a 14-15% reduction in material, which in turn means 15% less weight in wood for the structure to support. That means your structural members and foundations can also be made smaller, since they have less dead weight to support. Of course, dead weight is only one component of total force on the structure.

As gator pointed out above, it's easier to handle and work with than a single thicker piece. It's also probably more readily available locally, so it means less transportation cost. All that adds up to cheaper construction costs.

.

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Tuesday, April 14, 2009 3:15 PM

I also have a question along these same lines... Are the running wheels, upstops, and side wheels set up on woodies the same as they are on steel coasters? Try as I might, I've never been able to get a good look at the wheels on a wooden coaster, while it's hard to miss them on their steel counterparts.

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Tuesday, April 14, 2009 3:43 PM

and for the visual people

http://img10.imageshack.us/img10/3029/layeringsystem.jpg

thanks guys

Last edited by DorneyDante, Wednesday, April 15, 2009 1:31 PM
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Tuesday, April 14, 2009 4:52 PM

SOB used up most of the available Douglas Fir at the time. The track on Papa Beast was orriginally Redwood but is now virtually all pine stained red.

I've noticed a lot of a rides smoothness has to do with the width and thickness of the STEEL STRAP. I really first noticed it some years back when riding Thunder Run at SFKK that the steel was wider and thicker.

Most newer woodies use it. But look at older ones like American Eagle where its only about wheel width and the steel is actually shaved off. Not that AE was rough. Just boring when I rode it.Chuck

Last edited by Charles Nungester, Tuesday, April 14, 2009 4:53 PM
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Tuesday, April 14, 2009 5:29 PM

Redbeard, be sure to take a look at the photo that DorneyDante linked to. That photo shows a PTC-style wheel assembly and you can see that it differs from a typical (if there is such a thing) steel coaster design in a couple of important ways. First is that the guide wheel is located inline with the road wheel axle. Most steel coasters, if they have guide wheels, tend to use two sets, one ahead of and one behind the road wheel, so that the wheel carrier can steer. Second, notice that the upstop wheel is positioned inboard of the road wheel. You can see why: the upstop wheel rides under the track flange, but the road wheel is moved outboard so that it can ride on the part of the top board that is fully supported by the track stack instead of on the cantilever.

By comparison, steel track is usually a circular tube, so all of the wheels ride on various surfaces of the same tube, meaning the upstops are typically directly below the road wheels.

--Dave Althoff, Jr.

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Tuesday, April 14, 2009 5:36 PM

I've never heard of anyone using redwood for track, it's very soft and very expensive. According to the 1979 Beast press release the coaster was built of southern yellow pine, stained a redwood color.

I don't know if the thickness of the steel ribbon has changed much but the width certainly has. I don't know the exact dimensions but I think the old steel ribbon was 2" wide. Over the last 20 years or so most of that has been replaced with steel ribbon about twice that width. The wider width keeps the steel from getting pressed down into the wood. This is especially important when the wood layer is made of yellow pine. I'm pretty sure Charlie Dinn started using the wider steel ribbon, as number 2 grade southern yellow pine was his wood of choice.

Last edited by Jeffrey Seifert, Wednesday, April 15, 2009 6:09 PM
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Tuesday, April 14, 2009 6:32 PM

This is very interesting reading. I wish I had anything whatsoever of value to add to the discussion, but I don't -- except to say that it's fascinating.

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Tuesday, April 14, 2009 8:38 PM

I was in Jr High back then, I could swear I read it was made from redwood due to its flexibility and durrability. I COULD BE TOTALLY WRONG.
I ate this coaster up before it opened learning everything I could about it prior to my media night rides. Like I said, I could be wrong. CALLING CHARLIE DINN? Oh wait, I got people at work who built the thing!

The wood did not appear to be stained back then. The first staining I remember is when Paramount took over. Cut back all the trees and overhanging limbs and stained the whole coaster.

Tracks replaced almost every year and in some places more than once per year on that coaster.

Im told extensive track and structural work has been done by GCII this season and that SOB may not open with the park as that project was after Papa.Again, Im Uncertain of this. but the prior AT pics show that lots of track was replaced.

Chuck, who yesterday *April 13th* celebrated his 30th year beast aniversary of my first ride, Under a full moon after a dissmal 3hr rainy and cold wait for one train manually unlocking lapbars. IT WAS BLISS!

Last edited by Charles Nungester, Tuesday, April 14, 2009 8:42 PM
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Thursday, April 16, 2009 6:57 PM

Seen SOB testing both trains today.Chuck

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Thursday, April 16, 2009 10:05 PM

COOL! I'm going next week, and while I am extremely excited to ride Diamondback, I was also looking forward to giving SOB another chance. I haven't been to KI since the loop was removed. I rode SOB only 1 time near the beginning of the ride's opening. I've been to the park about half a dozen times since then and never desired to ride that torture device again. It'd be nice to see if it is tolerable or not now that it is supposedly fixed.

I thought that I would never ever say this...I hope SOB is open by next weekend.

What do some of you think about SOB now?

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