Straight track is named according to length and type:

Let's look at piece that's named A1t100mstrt.s

Breaking down the name:
A = all track pieces start with A
1 = number of tracks
t = this is a track
100m = length of track
strt = straight track (Tun, RndTun, wtr = suffixes for Tunnel, Round Tunnel, water)

So this example is a single straight piece of track 100 metres long.

Straight track is available in single double and triple track:
Single: 10, 50, 100, 500 metre lengths: plain, Tunnel, Round Tunnel, Water

Curves are handled slightly differently: the name gives you the radius and the arc swept by the curve (360 degrees = circle, 180 degrees semicircle, etc).   A piece such as one named A1t1000r10d....
A = all track pieces start with A
1 = number of tracks
t = this is a track
1000r = radius of of track in metres
10d = the arc swept by this track (therefore 36 pieces to make a full circle)
(Tun, RndTun, wtr = suffixes for Tunnel, Round Tunnel, water)

Curved track is available in single double and triple track:

• Single track:

  500 metre radius:  5, 10, 20, degree plain;   5, 10 degree Tunnel/Round Tunnel
  1000 metre radius: 5, 10, 20, degree plain;   5, 10 degree Tunnel/Round Tunnel
  1500 metre radius: 5, 10, 20, degree plain;   5, 10 degree Tunnel/Round Tunnel
  2000 metre radius: 5, 10, 20, degree

Compute length in meters like this. First find the circumference of the full circle: 3.14 x (radius) x 2. In the above example 3.14 x 1000 x 2 = 6,280m. Then divide that by 360 to give the length in m of a 1 degree section of that circle. In the above example 6,280 / 360 = 17.44m. Last multiply that answer by the length of your curve in degrees. In the above example 17.44 x 10 = 174.4m.

		
	250m5d   =  21.8m
	250m10d  =  43.6m
	250m20d  =  87.2m
	500m5d   =  43.6m
	500m10d  =  87.2m
	500m20d  = 174.4m
	1000m5d  =  87.2m
	1000m10d = 174.4m
	1000m20d = 348.9m
	1500m5d  = 130.8m
	1500m10d = 261.7m
	1500m20d = 523.3m
	2000m5d  = 174.4m
	2000m10d = 348.9m
	2000m20d = 697.8m

Contribution by "saddletank".

Points (or switches) are named as to their direction and curvature; for example,  A1tPnt10dLft is a single tracked, 10 degree Left hand point; A1tPnt10dLftMnl is the same point, but manually operated.

Points come in 2.5, 5 and 10 degree levels of curvature.

Automatic points will be operated by the (computer) dispatcher during an activity, whereas manual points must always be thrown by the driver (all points are set manual during an "Explore the Route" activity).  The point's matching reverse curve is named A1tEndPnt10dRgt. This allows the loop line to return to parallel to the mainline and at the same length.  To line up the ends of the track you need 20 metres of straight track (two 10 metre straight pieces (see image below)) for a 10 degree point........

or 70 metres (50+10+10) of straight track for a 5 degree point (see comparison image below).

There are two types of buffers: standard and US:  see image below:

This file is woefully incomplete, but there are only so many hours in a day!  I hope this much helps someone make a start.  It DOES get easier the more you work it.

I've catalogued and documented every piece of default track section and placed them in an Excel spreadsheet (saved as Excel 5.0/95 so as to be as backwardly compatible as possible).

Click on the image at right to commence downloading a 50k .xls file which contains the name and description of every default MSTS Track Section. One sheet is "read-only" to keep it in the same order as the Placement | More selection box, the other is "read-write" which you can sort to see what track sections are available.

(*This table provided by OzinOz in a message on the Train-Sim.com MSTS Routes Forum - Stuart Thurstan has a similar table in the libraries at Train-Sim.com).

The elevation listed in MSTS is in degrees. Apart from being confusing, it is not in wide use.   The solution is to convert to percentage (or as we Aussies prefer the gradient ratio,) it is 1 / sine of the angle degree of gradient, or the sine of the angle x 100 if you want the gradient percentage).

The table below lists the gradients in MSTS degrees, Gradient % and Gradient Ratio: I've included standard grades (ie 1%, 2%, 2.5%) as well as all the MSTS steps:

Degrees .............Gradient %........... Ratio
0.100..................0.18..................1:570
0.150..................0.26..................1:381
0.200..................0.35..................1:285
0.300..................0.52..................1:190
0.450..................0.78..................1:127
0.575..................1.00..................1:100
0.600..................1.04..................1:95
0.750..................1.30..................1:76
0.900..................1.57..................1:63
1.050..................1.83..................1:54
1.150..................2.00..................1:50
1.200..................2.09..................1:48
1.300..................2.20..................1:44
1.433..................2.50..................1:40
1.500..................2.62..................1:38
1.600..................2.80..................1:36
1.750..................3.05..................1:33
1.900..................3.31..................1:30
2.050..................3.57..................1:28
2.300..................4.00..................1:25
2.450..................4.27..................1:23
2.600..................4.53..................1:22
2.750..................4.79..................1:21
2.870..................5.00..................1:20
3.000..................5.23..................1:19

As you can see, what was initially thought to be a gradient percentage, say 3.00% (which is not too bad - 1:33), actually equates to greater that 1:19, strictly Shay and mountain goat country.

You can adjust the gradient in small increments by holding the END key while adjusting the gradient.