Derails

[SteamGene]

You've said that your benchwork is not held together.  While each section may be solid, the fact that they are not a unified whole makes the entire thing unstable.  Look at modular layouts, designed to be taken apart and put together.  They have a means - normally C-clamps- to lock each module to its neighbors.  You need the same thing. 
Gene

[Conrail Quality]

Well, it doesn't move...that's....solid....

But the trains will move...horizontally

[r.cprmier]

raintrain;
Gene gave you some good advice.  What's wrong with you?  If you build or use halfassed ANYTHING in this area, it will fail!!!  Pay attention to people who are experienced at this stuff!  You'll fare better.

Rich

[kevin2083]

But the trains will move...horizontally

still better than vertically,  though

[chuff_n_puff]

You have been gave some good advice on track  buliding. Take it from experience, if you don't have good, solid, level, smooth jointed track, you are going to have derail nightmares. I had to learn the hard way, as none of my trains would run without derailing. You can not have any sudden inclines or declines either. You have to make a gradual change in all grades. I tore up 150 feet of track and started over and finaly got a trouble free track, but only by making sure every piece was perfect. You can't even have a piece that is not secured without asking for trouble, especially in curves. If it wiggles the least bit, you got a derailment. I could never get the hang of track nails, with EZ track, as most of the time they would warp the rails beside of the nail. I hot glued all of mine in place and used grass and rocks to cover up the glue. I got 3 sets of rails now and can have 2 trains running on each rail for hours and have no problems!

[rains train]

Well, the people at K-10's (train store in my area) told me the foam would work, they've been working with trains for a long time 

[SteamGene]

Foam works.  No question.  Foam between platforms works, as long as the platforms are solidly fastened together. 
You've got a lot of guys trying to help you.  You know the joke about the guy praying to God to win the lottery and finally God says "Give Us a break.  BUY A TICKET!" ?
Buy a ticket.
Gene

[rains train]

Okay, I'm going to fasten the legs together and get some foam, and hopefully it'll work! 

[rains train]

The foam is working beautifully!

[glsummers]

derail, a lot of guys gave you a lot of grief and could have been more gentle. The key to everything you do to run nice smooth trains is make that track work as smooth as you possibly can. Do what ever it takes and what ever method that works to get the roadbed smooth. I work on a club layout that did not have good bench work. It was solid but they did not have it very smooth. I have used everything from foam to drywall hot mud to cark stock to get the track smooth. Merry Christmas. Larry

[Guilford Guy]

How about some pictures. It may help us figure out what is going on better than what we understand now...

[rains train]

Its fine now guys, the foam is perfect! Makes the unlevelness into a grade..which the trains can go down without derailing!