Head-end View wrote:Thanks Flat-Wheeler. I was already figuring on #6 turnouts..............What's the purpose of the transition curves and why do you say not to use Bachmann track? You might be right about the grades. The above-mentioned link included a chart showing that you need a 12-ft. run just to get a 3-inch height using a 2% grade. BTW, will a 3-inch height even clear an HO loco running under it? .......if you use Atlas-100, do you necessarily have to put some kind of ballast under it? (A buddy uses cork) Or can you just nail the track to the plywood surface? I'm told it's noisy if you do that?
Transition / easement curves are used by real railroads when entering a sharp curve. It basically is a gradual reduction in radius from the straight to the middle of the curve, or in other words the curve gets sharper towards the center of the turn, and then gradually eases back to a straight. It serves to reduce lateral/ centripetal forces on the train and outside rail on tight curves. Usually the railroad will gracefully combine this with "super elevation". A super elevated curve is one that has track tilt downward towards the inside of the curve, so they outside rail is higher than the inside rail. It is similar concept to a banked turn on car racing track, except much less noticeable. Again, this is another form of art for the more advanced modeler to replicate. It's not that easy, and if you don't get it right, long cars and engines derail consistently.
A 3" height from top of rail head to rail head top, will clear an HO loco, and quite likely a hi-cube boxcar. Just don't forget you need to accommodate the bridge depth plus clear cars a lil' bit taller than the engine.
You don't have to ballast, or put anything under your Atlas 100 track. However, ballast looks more real. Cork, foam, homasote, or whatever you put underneath serve to absorb the noise, and to lift the track up from the surrounding ground level terrain (for water runoff & drainage on the prototype).