The Transcontinental PRR

[eric220]

Shifting gears, one of the next major projects is the helix. CodyO and I have been talking about it offline, and he's trying to talk me into using Unitrack. There's no way to do it with the wood ties track, but there is a superelevated concrete tie set that might work. My minimum mainline radius is 18" radius, and that set's inside radius is 17 5/8", but that's pretty darn close. I don't have anything right now that can't handle 15" radius, and if those 3/8" become an issue with something down the road, I can always send it down the 18 7/8" outer track. The tighter radius bumps the grade up to 2.02%, but I'm pretty sure that difference falls within the tolerance of my ability to properly align the grade. Then there's the concrete ties, but I'm thinking spray bomb the whole thing brown, clean the railhead, and ballast for the visible sections.

I like the idea of the reliability of the Unitrack, but I'm not a fan of the superelevation in a helix, and I'd prefer that those curves be a little broader. Additionally, although I have the C55 flex to do the project, I don't have the rail joiners. The Unitrack has the definite advantage of being available.

Thoughts?

[peteski]

I like the idea of the reliability of the Unitrack, but I'm not a fan of the superelevation in a helix, and I'd prefer that those curves be a little broader. Additionally, although I have the C55 flex to do the project, I don't have the rail joiners. The Unitrack has the definite advantage of being available.

Thoughts?

Just one thought from me: If not Unitrack, why insist on C55?  You can just as easily use taller rail - after all it is a non-scenicked (and probably mostly hidden) part of the layout.  Who cares how tall the rail is?  It would be a problem the other way around (if you were using pizza-cutter wheels), but there should not be any disadvantages to using C80 track in there.

[eric220]

Most of the helix will actually be exposed. I don't want the trains disappearing for 1/3 of the mainline run. I'm planning on doing minimal scenery on each loop.

[peteski]

Most of the helix will actually be exposed. I don't want the trains disappearing for 1/3 of the mainline run. I'm planning on doing minimal scenery on each loop.

Ok then, Unitrak is already C80. Using C80 flex won't look all that different (and C80 flex should be cheaper than C55 or Unitrack).  I'm not sure how well super-elevation would work in a helix.

[eric220]

The main attraction of Unitrack is the reliability, followed by availability. Like I said, I've already got the C55 flex to do it, I jut don't have the joiners. I really don't see any significant advantage of using C80.

[peteski]

... I've already got the C55 flex to do it, I jut don't have the joiners.

I guess I skipped right over that statement. 

[GaryHinshaw]

You can use Peco joiners with Atlas code 55.  They're available.

[packers#1]

I think the main question is can your tracklaying skills (or those of whoever would lay the track in the helix) on par with or superior in respect to unitrak? From what you've said the radii seem compatible, so really the question is reliability. If the C55 can be laid to be on par with or superior over the Unitrak, I would use that. Otherwise, I think Unitrak would be well worth the investment, especially in something as important as a helix.

[C855B]

I wouldn't superelevate a helix. Stringlining forces want to pull the train into the center, and superelevation gives it a head start.

[eric220]

I think the main question is can your tracklaying skills (or those of whoever would lay the track in the helix) on par with or superior in respect to unitrak?

I know for a fact that my track laying skills are not up to the task of replicating the legendary reliability of Unitrack. I'm reasonably sure that I can do it, but I do fear the track joints on curves. That lack of confidence is one of the reasons that the helix project has stalled for over a year.

I wouldn't superelevate a helix. Stringlining forces want to pull the train into the center, and superelevation gives it a head start.

This. The whole thing would be less of a quandary if Kato made flat curves in the appropriate radii. Cody insists that he's had 0 problems with his 15" superelevated helix, so I'm still considering it.

[packers#1]

Well why not save the flex for something else and use sectional track, which is still cheaper than Unitrak but will take care of the issues of track joints in the curves?

[eric220]

AFAIK, sectional track can still be prone to kinking, and it vastly multiplies the number of rail joiners involved, increasing the number of power drops. I guess I'm not necessarily opposed to it, I just don't see the advantages outweighing the drawbacks versus flex.

[DKS]

AFAIK, sectional track can still be prone to kinking, and it vastly multiplies the number of rail joiners involved, increasing the number of power drops.

...unless you pre-assemble full circles before laying it by carefully aligning the sections over a guide line and soldering all of the joints. No kinks, no power loss. A fair amount of work, yes, but the end result will look good.

[CodyO]

To all the super elevated doomsday people

The strong lining doesn't happen I've run trains up to 75 cars up and down my super elevated helix which is also using the smaller radius

My thing with unitrack is simply you'll have great track work where great track work is really needed
You'll never get that with flex plus you'll have to worry about kinks and expansion problems

Plus of you run into problems with with how you cut a support you can single handed remove re-cut the support and replace in under 8 hours

Oh and if a train of 50 cars gets cut lose at the top of the helix they will make it all the way back down without derailing

[eric220]

My other concern with sectional is that I presume it's just as endangered a species as the rest of the C55 products. I'm going to need 5 turns' worth. Is that even available right now?

Also coming to mind is that if I assemble each half-circle as DKS describes, I'm liable to melt quite a few pieces. (I have no experience soldering track.) In the end, is it going to be more work than putting enough lipstick on the Unitrack to make it passable?

My main draw to the Unitrack is still the idea of reliability. Flex or sectional, I don't think I'm going to be able to match it. All it takes is one lump under the cork, or one spec of misplaced solder, or a screwup of any kind in the hundreds of installation steps and boom, my helix has issues that are going to be a royal pain to fix once it's fully installed.

That versus more flexibility with geometry, no superelevation, and track that is easier to finish cosmetically.