can someone please tell me the width of clearance between paralel tracks
Gidday, here’s a link that should help.
http://www.nmra.org/standards/sandrp/s-8.html
Cheers, the Bear.
Allowing 2" track centers for straight and adjusting w/ the spiral easements into turns to a 2 1/2" centers will work for most equipment and still has a decent look. The 2 1/2" center spacing for the turns could be dropped to 2 1/4" for radii larger than 36", but would still check all clearances of pilot overhangs and long truck center side overhang. A large steam (especially ridged frame) inside can have pilot interference w/ a passenger on outside. As radius decreases the clearance becomes tighter.
According to the Dean of Track Design (John Armstong):
Straight Track center minimum is 2 inches apart.
Curves depends on radius but a good liberal rule of thumb is to allow 2 1/4 inch between a curves in the range of 24-inch to 30-inch radius and a curve on either side. 2 1/2 inches is a liberal and safe distance on curves.
Do yourself a favor and get John Armstrongs “Track Planning for Realistic Operation”. Lots of good stuff in there.
What scale?
The 2" is nominal for HO, N scale is typically 1.25 to 1.5".
Depends on the railroad that you are modeling. An old time sort of layout would have them closer together. There were different standards on different railroads, but as a rule of thumb, the newer the line the further apart the lines would be. This of course allows for longer cars and wider loads.
Lay down your first track. Take the longest car that you will use. Place a felt pen on the table and against the outside corner of the car, and push the car around the curve. This is the minimum outer envelope of this track. Now do this again holding the pen at the middle of the car on the inside of the curve. This is the minimum inner envelope for this track.
If you are building a second track on the inside of this one, remember that the outside envelope on this track (the inside envelope too) will be wider than the envelope on the first track. In other words, if the distance between your first center-line and and the outside envelope guide will be smaller than the envelope required by your second track. You will need more distance between the center-line of your second track and the outer envelope of that track.
In addition to these minimum clearances for trains, you also need space for equipment and workers to clear up between trains.
NYCT used to run 67’ trains on the Jamaica line. later they started using 60’ cars on that line, while at the same time they began to buy 75’ cars for other parts of the railroad. These 75’ cars could never operate on the Jamaica line specifically because of clearances on some of the curves as they would side-swipe each other. (Now all new cars are back to 60’… 75 foot cars are being phased out). As you may imagine, railroads have very specific specifications for their envelopes. The trackway requires a specified envelope around the entire train as measured from the rail heads. The Wayside requires a specified envelope around the entire track as measured from the rail heads, and this is a much more generous envelope as related to
This is all good advice. It can be summed up thusly: The trains will tell you. More correctly, YOUR trains will tell you.
Do trials with curves and spacings to see what is the least you can safely do. Once you have those minimums that apply to your particular trains, map it out and build your system.
BTW, this appliesas well to grades where you change elevations. Do trials.
Crandell