Okay...where to start??? First, I completely disagree that ME Code 55 is especially fragile, or comes from the factory bent...either side-to-side or vertically. That has NEVER been my experience with it and I've used it since it was called Rail Craft back in the mid 1980's, using Rail Craft Code 70, Rail Craft Code 55, Rail Craft Code 40, Micro Engineering Code 55, Micro Engineering Code 40 and the newer Micro Engineering flex produced from Micro Engineering's new injection tool, which offers less fine details and more uniform (less prototypical) spike head detailing.
I've laid tons of it since the Ntrak club I was associated with decided to go with a different modular standard, which included using ME Code 55 as mainline trackage. I've laid it on both my own modules/sections/layout and on many friends and customers modules/layouts.
Since the ties on ME Code 55 are not all placed perfectly aligned (their centers vary a bit from side-to-side, just like prototype rail...which is one of ME's selling points...more realistic looking) it is impossible to get straight rail by trying to align the tie ends with a straightedge, since the tie ends will not be aligned with each other when the rails ARE straight.
The very best method for me has been to:
(a) Use
UNWEATHERED flex. The weathering makes the flex stiffer and adds an additional operation to soldering feeders and rail joiners (removing the weathering)
(b) Lay it to a centerline on your cork roadbed...which must be sanded smooth with a sanding block that is about 8" long with 220 grit paper attached to it, made from a 1X2 straight pine block. This means your cork roadbed should be laid to a marked centerline on your subroadbed, one half of the cork roadbed closely following your marked centerline on your sublroadbed
(c) For straight rail sections, progressively work the kinks out by pressing the rails gently on either side of the flex, working with a thin metal straightedge laid alongside the RAIL...not the tie ends, until you are pretty close to straight
(d) Put your head down on the track and sight along its length which will magnify any bends that are there, and while sighting along the flex, extend an arm and put your pointy finger on the middle of the kink you want to correct and keep it there as you raise your head up off the track and use both hands to gently bend the rails as straight as you can...then check again. Keep doing this until your track is visually straight, then check overall straightness with your metal straightedge and your cork's centerline. This works for curved trackage also and for getting your solder joints perfectly straight. It's commonly called "The M1A Eyeball Method".
As you're working your track, you're going to find your tie spacing is going to get wonky. Straighten and space the tight ME ties as you work. Also, at the ends, get rid of any ties that don't have spikes, and cut away three or four sets of the little under-the-rail tie spacers so you can slide ties away from your future soldered rail joint, then slide them back after the rails have cooled.
Now, on to glues. I glue my Midwest Cork Products N-scale Cork Roadbed down using yellow carpenter's glue...and I don't try to save a nickel. I use the best quality and have found that Titebond III Ultimate Wood Glue does an excellent job. Since I'll be bathing my cork roadbed in water/glue ballast cement later, I feel like the waterproof aspect of the Titebond III Ultimate Wood Glue is important. I have an assortment of lead weights from my SCUBA-diving days and I use them with straight pine boards of varying lengths to make the cork lay flat while the glue is curing/drying. After the glue is cured, I sand it flat.
After I get my ME track bent to exactly the specification I am satisfied with, I start at one end and press down on the track with a straight piece of select pine...about 3" long and run watery Cyanoacrylate along the tips of the ties on either side of the rails so that capillary action sucks it under the ties...then I quickly squirt both sides with Accelerator, to set it off...all while pressing down with my little pine block. This glued section is only about 1.5" to 2" long. I then go down the track about 6" and do another short glued section the same way. I am "tacking" the track down, and checking its alignment as I work. Checking and rechecking is the only way to ensure you're laying your track to your specifications, just like laying prototype track. I use the little 3" long pine block to press down on the tops of the rails so that I don't glue my fingers to the rails, and I don't press hard, just hard enough to ensure that little section of track is flat against the sanded cork roadbed.
During this tacking process you're going to find that you still need to do some adjustments on your track. Try to make sure these adjustments happen on unglued portions of your track.
I don't tack down the last 6" or so of track since I will be working with it to join another piece of flex to it, and I want to be able to both bend it, and slide ties back and forth.
At some point, the smell of Accelerator may get fairly overpowering, so I use an old hair dryer/blower to quickly evaporate the Accelerator, which also deactivates it and allows the odor to quickly dissipate.
After I've got about a 3' long section of track tacked down, I run my fingers along the top of the rails to feel if there's any hardened CA there, and chip it off using a #11 X-acto knife. You can do this to get it off the tops of your ties and sides of your rails too. The trick to minimize this problem is to cut your CA's pointy applicator nozzle so the hole is as small as it can be. You don't need a LOT of CA to tack your track down.
At his point, I attach feeders to the rails if they're not connected to previous powered rails, and power up a smooth running test engine pulling a car or two on your freshly tacked-down track. See if it wiggles, then mark the spot it has wiggled with your pointy finger again, check the rails at that point and adjust if you need to. Sighting down the track with your eye magnifies any wiggling that may occur.
Once you've got it "perfect" it's time to glue the rest of your track down using the same method as above, except doing it in lengths that are the same length as your little pine block. This time, make sure you dry each glued portion with the hair dryer before proceeding on down the track with your next glued section. This keeps the CA from setting up prematurely and possibly setting off your entire bottle of it you're using.
Although this does a pretty good job of gluing down your track, CA really doesn't stick all that well to engineering plastic. It will be your track ballasting cement that really "socks it down".
However, I've had unballasted sections of track laid for decades that have not come up on my portable layout, so....the CA really does a pretty good job of gluing it down.
If you make a big mistake, you can pop the track up using an artist's pallet knife, soften the CA on the cork roadbed by using CA solvent and scrape it off. I've also recycled my Rail Craft and old ME Code 55 track by carefully prying them off using my trusty artist's pallet knife, then wire brushing the bottoms of the ties to remove CA remnants. This sometimes leads to vertical bending, but if you're careful you won't get any big kinks, and the small vertical curvatures can be easily corrected using the M1A Eyeball Method again.
Photo (1) - Finished superelevated Rail Craft Code 55 mainline trackage at Echo Curve, painted, ballasted and weathered: 
Photo (2) - Same trackage at Echo Curve with trains on it:
Here's something that maybe you haven't considered...BIG ugly rail joiners. It's a real shame to put full-sized rail joiners on ME Code 55 track, which means when you sight along your rails, you're going to see gaps in the spike heads where there are rail joiners, and the ties you use will either be lower than adjacent ties, or have the "tieplates" ground away so they fit under the extra depth of your stock rail joiners.
Here's my solution to the problem, which I'll illustrate with photos. If you're interested in exactly how to do this, I'll write up a more detailed explanation and post it here.
Photo (3) - Cut rails at future solder joint so that both sets of rails meet in the middle the space between the same two ties. Cut away the spacers between a few ties and slide them back away from the future solder joint. This is new ME Code 55 track:
Photo (4) - Shortened rail joiners soldered in place with ties slid back in place after rail has cooled on new ME Code 55 track:
Photo (5) - Shortened rail joiners after a single coat of Krylon Camo Ultra Flat Spray Paint:
Shortened rail joiners are made from tight ME Code 55 rail joiners, slid on to a scrap piece of rail and both rail and joiner are cut at the same time to prevent the rail joiner from crushing. You can get two or three short joiners from a single normal length rail joiner if you have sharp flush cutters.
One more thing. Although it is generally accepted as a sign of meticulous craftsmanship, getting perfectly straight trackage is more common on model railroads than on the real deal. While documenting the mainline UP trackage I am modeling on my layout, when looking at the photos, it was pretty obvious that prototype trackage is full of kinks, bumps, rotten ties, different odd lengths of ties and other imperfections. Because of this, I purposely made my Branchline Park City Yard at Echo with crooked track...just like the prototype.
Photo (6) - UP Trackage at Baskin Siding in Echo Canyon showing uneven track in the siding and (if you look closely) uneven track on the mainline too:
Although there may be other methods that fit your needs better than what I'm recommending, my methods have worked well for me for many years.
Have fun!!
Cheerio!
Bob Gilmore
