--- In [email protected], "ecphora123" <[EMAIL PROTECTED]> wrote:
>
> A 2% grade (or any other percentage)is easily measured and
> constructed in a straight track situation, but just how does one
> accomplish the same on a curve? how do you draw a track plan for a
2% grade
> on a curve, knowing that each point on the curve is at a 2% increase?
The larger you draw the plans the easier it is to scale the length
around curves. I like to use 1/2 inch = 1 foot as a minimum and
prefer 1 inch or 1.5 inch if possible. The rise and run formula works
for scale or full size. If you can find a flexible ruler it's fairly
easy to measure length following the curve centerline and then
calculate the grade at any point along the way. A calculator can give
the length of curves if they are 90 degrees or 180 degrees(or any
amount if you can measure the central delta angle). I've never tried
the common model railroad layout design software programs but they
should contain some kind of circular arc calculations for length and
grades?
Real railroads keep track of grade and distance by using "stations".
from a given starting point defined as 0+00 if they go 100 feet along
the line it is called station 1+00. one hundred more is station 2+00,
another 150 feet would be 3+50, another 6 inches would be 3+50.50,
one mile from starting point would be 52+80, etc. Each station has a
grade determined by the design profile. The stations continue around
curves measured on the centerline of the track. The grade between any
two stations can be calculated by rise and run.
I've stationed plans for layouts with complicated grades. It can be
done in inches from starting point or in scale feet, the elevation
units have to match the length units, (scale feet or actual inches).
Once the layout is stationed it's easy to calculate the finish grade
at any given spot and to get riser heights above the existing table or
framing, the real railroads call these heights cuts or fills, cuts if
the finish grade is below the existing and fills if the finish grade
is above the existing......dave
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/S-Scale/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
