Greetings Gene and Other Esteemed Colleagues,
The NMRA Standard S-7 is a good place to start. You can find it at:
http://www.nmra.org/standards/s-7.html
For S-Scale (standard gauge) they state the minimum vertical clearance
is 4 1/8 inches.
Of course, that means the distance from the top of the rail to the
lowest, allowable item above the track. Suppose, for example, that we
have track with 1/8 inch ties and code 100 (.100 inch) rail. If we wish
to use a bridge that has a deck an inch thick, we would need the base of
the overhead track to start at 5 1/8 inches. To total rise required
would be:
4.125 inches for clearance plus
1 inch for the bridge bottom chord plus
.125 inch for the ties plus
.100 inch for the rail.
The total would be 5.35 inches of rise.
5.35 is 2 percent of 267 inches of run.
5.35 is 3 percent of 178 inches of run.
I use a home-made tool to measure running distances. It is a plywood
wheel attached to a plywood handle. The circumference of the wheel is 12
inches. It is marked along the edge at ¼ revolution points. I can roll
it along the centerline of the right of way and count the turns of the
wheel. The result is accurate to within an inch or two close enough
for this job. Ill take a picture of the thing and post it on my web
page, tonight. Ill let you know when it is up there.
Good Luck,
Bill
Reply from Bill Porter
-----Original Message-----
From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf
Of ecphora123
Sent: Thursday, July 13, 2006 5:14 PM
To: [email protected]
Subject: {S-Scale List} Grades and Vertical Clearance
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? Does one mark a length of flixible
track prior to bending it to the desired curvature, knowing that
various marked points must be at some elevation which complies with
the 2% increase? I suppose that this works if you are actually
constucting a layout, but 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?
Now, if you are still with me, how much higher must a track or tracks
be in order to cross over other tracks. A friend who insists for what
ever reason (must need some sort of professional intervention L.O.L.)
on modeling in HO tells me that he uses a 4 1/2 inches minimum for
his clearance. What is the accepted minimum vertical clearance for S?
How do you plan grades on paper so that a bridge at a specific place
on the layout will be high enough over other tracks? This is
especially important if you are pre-planning scenes for their visual
impact. Again, a curved or straight grade would make such planning on
paper essential.
Thanks to all,
Gene Cimino
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