Horseshoe Curve Radius in HO Scale

[MGAMike]

Hi There!!

I am planning my new model railroad and I think I would like to incorporate Altoona's Horseshoe Curve.  The real thing is 1,300 feet across which roughly calculates to a 90" radius in HO Scale.  Since I do not want the curve to take up half of my train room, does anyone have any opinions or thoughts on what radius would make for a good representation of the curve?  My planned minimum radius for the layout is 32".

Any thoughts or advice is appreciated.

Thanks,Mike

[davidmurray]

Mike:

It seems that you have answered your own question. " 32 inches is your minimum curve, but bigger would be better."

Horseshoe curve is distinctive, the mountain and scenery will tell everyone where they are.

Dave

 

[Steven Otte]

The prototype curve is usually seen from inside, since it's surrounded by mountains on three sides. This is also a convenient way to model it, with the heavily wooded mountains providing a perfect backdrop to the scene. So if you want to give viewers of your layout the same feel when seeing your modeled Horseshoe Curve, you'll want the viewers to be inside the curve, which means your curve will need a radius wide enough to put a sufficient viewing aisle in the middle. If you're planning a 32" minimum radius, and we subtract about 6" on each side for scenery between the track and the fascia, that gives you a 4'-4" center aisle -- plenty of room for viewers.

Another option would be to wrap Horseshoe Curve around the outside of an aisle that surrounds a peninsula. A 32" radius turnback curve, adding a few inches on either side for scenery, would give you a peninsula 6 feet wide. Add 4 feet for two 24" aisles on either side, and then a few more inches for scenery, and the inner track of your Horseshoe Curve would be at least 64" radius. A 3-foot aisle on either side of your peninsula gives you a curve of 76" radius. This approach puts you closer to the prototype, but most people viewing it would see it as "straight" track that just happens to wrap around a curved aisle, rather than a faithful model of a prototype curve. So, there are tradeoffs.

[cuyama]

I've done a couple of PRR Horseshoe Curve designs in different scales. Personally, I think that the curve should be viewed from the inside to be most realistic (that's the viewpoint for visitors and virtually all photos). 

In my opinion, a key to communicating the scope of the real thing is having the ends of the straight tracks leading into curve well out of sight when one is viewing the middle, if possible -- but one must often compromise to fit the available space. If there was room, I'd try for a bit wider than 32" radius for the inner curve to give a real feeling of breadth to the scene.

Good luck with your layout.

Byron

[7j43k]

32" radius:

 

If I put my arms straight out to the sides, my fingers are a good bit wider than 32" + 32".

Seems kinda small to me.  Maybe 48"?

 

 

Ed

[superbe]

Mike,

Welcome and good luck with your ambitious project.

Hopefully you will post pictures of your progress.

Bob

[cuyama]

I remembered an article on an HO Horseshoe Curve layout from Model Railroader, December 2002. The radius is probably close to 32", but the builder (Mike Shanahan) filled-in the curve area with a representation of one of the reservoirs. So the viewer stands away from the curve itself.

I personally don't think it works as well as standing in the center of the curve, but it’s a data point.

[Anonymous]

cuyama

but the builder (Mike Shanahan) filled-in the curve area with a representation of the reservoir. So the viewer stands away from the curve itself.

There is a club layout at the Time Machine hobby shop in Manchester, CT that did this thing. 

 

cuyama

I personally don't think it works as well as standing in the center of the curve, but it’s a data point

I agree with this statement.

[Anonymous]

MGAMike

Hi There!!

I am planning my new model railroad and I think I would like to incorporate Altoona's Horseshoe Curve.  The real thing is 1,300 feet across which roughly calculates to a 90" radius in HO Scale.  Since I do not want the curve to take up half of my train room, does anyone have any opinions or thoughts on what radius would make for a good representation of the curve?  My planned minimum radius for the layout is 32".

Any thoughts or advice is appreciated.

Thanks,Mike

 

What era are you modeling? 

It matters...  at some point one track was removed (it was 4 tracks, now 3).  I want to say either Conrail or NS did the track removal..

This also affects your radius.  See new NMRA RPs for track centers

 https://www.nmra.org/sites/default/files/standards/sandrp/pdf/rp-7.2_curved_track_centers_july_2017.pdf

What I gather from that is that you would want to lay the inside curve at 32", the next at 34 9/16", the next at 37 1/8", the outside at 39 11/16".

For post 4th track removal (Im not sure what PRR's track numbering convention was):

Inside 32", (track removed), 35" (ball park), 37 9/16".  

Steam era would be 2 19/32" between each total of 4 tracks

(I would go with 2 5/8" just for sanity's sake...for all of them if you can afford the space)

[KemacPrr]

Conrail removed track two in 1981/82 It's the second one in from the center by the way. So your track number one would be the tightest radius. Using your idea of a 32'' radius for track 1 then track 2 would be 34 1/2 track 3 would be 37 and track 4 would be 39 1/2. This is using a 2 1/2 '' spacing on curves. If you had a foot of scenery on each side of the inner track 1  this leaves 40'' for your aisle width. About enough for one person with room to easily move. Remember multiple tracks equals multiple operators ! ---   Ken 

[carl425]

I don't think your issue is so much what radius you choose, but rather how you distinguish it from the rest of the curves on your layout.  If you look at the map, with the exception of a couple less than 90 degree curves, there is nothing close to as tight as the horseshoe for miles in each direction.  If you go with 32" radius for horseshoe, I think the rest of your curves would need to be substantially broader in order to make horseshoe look like the exception it is.

[MGAMike]

Thank you all for your thoughts!  I will be modeling the modern three track NS era and hope to be able to loosely represent the line from Altoona to the tunnels at Gallitzin.  I will be "starting" in a yard, climb the grade through the curve, and then enter the Gallitzin and New Portage Tunnels where the line will drop down a helix in the mountain and return to the other end of the yard.  This should allow for continuous running.  As mentioned, I need to keep the radius tight enough to separate the curvature of Horseshoe from the rest of the layout while providing enough space for viewers, both real and those modelled in the park. Oh, and I can't forget the display locomotive and funicular!!

Thanks again for all the insight!!

[Anonymous]

MGAMike

Oh, and I can't forget the display locomotive

The GP9 (or is it a 7) is pretty easy to come by.  

You might consider (if you have the time and money) to ride the Pennsylvanian (Amtrak train) through the area you plan to model.  The Eastbound train goes through the curve in daylight.

[MGAMike]

BMMECNYC  --  I agree with you and have already done that!!  I live less than three hours from Altoona and have been there countless times.  I think that is one reason I would like to model it, not to mention the triple track, heavy haul, high traffic action!!  I figure I will be making several more research trips!!

Thanks!

 

 

 

[rrinker]

 Yes, that was a great ride. I almost missed the curve because I was falling asleep - it was a long night from Chicago to Pittsburgh on the Cap. I barely slept in my bedroom, not because I couldn't fall asleep on the train, but because I too interested in seeing what little I could at night) since I had never ridden that train. The 2 hours sitting in the horrid Pittsburgh bus stop, err train station didn't help. At least I had a business class seat on the Pennsylvanian since the vending machine in Pittsburgh ate my money and I didn't get my orange juice. Free drinks with business class, so I got my juice! Kept seeing railfans out taking pictures of our train, had no idea why they were all so interested in a regular train like this - when I got to Harrisburg I found out why - the locomotive was one of Amtrak's Heritage units.

 I had previously been to the Curve to watch trains, but being on one (and I was coherent enough when I got on in Pittsburgh to sit on the proper side of the car!) ws really something, it comes up suddenly - nothing to see but trees...trees....boom, the whole valley is spread before you.

 Also interesting was goign through the complex flyover junction that is shown in Armstrong's Track Pllaning for Realistic Operation, where one set of tracks turns South on the West side of the river to go to Enola and the other tracks go across the Rockville bridge and on to downtown Harrisburg. Unlike what you see in Armstrong's book, the area is now all overgrown and it's hard to spot some of the features as the train speeds over it. Absolutely would do it all again, except I'd get on/off in Lancaster instead of Harrisburg, it's a lot closer to me.

                                             --Randy