What is the minimum recommended distance between the centerlines of parallel HO scale track? Does this distance differ for mainline track vs yards?
Thank You,
Ray B.
2" is a good rule of thumb.
Some use 2 1/4, or even 2 1/2.
For yard trackage you can go a little tighter 1 13/16.
but grab a boxcar add the width of your thumb and index finger
and that is a better practical width.
First, recommended model practice:
- Parallel tangent (straight) tracks, NMRA recommends 2 inches. Yard and other high-density tracks may be closer, but that can cause problems with wide models.
- Concentric curves, the spacing varies - more space for tighter radii. 2 1/2 inches is a good rule of thumb but should be determined by experiment if you run articulated steam, full-length passenger cars, 89 foot humonguboxes or other outsize goods vans.
Then there is prototype practice (dimensions given in full size and in HO scale):
- Parallel tracks in extremely congested steam-era freight transfer facility (CNJ Bronx Freight House) - 10 ft 6 inches (1 7/16 inches,) totally impractical for anything but pre-WWII short, narrow cars.
- NYC double track (built 1860) - 14 feet (close enough to 2 inches as not to matter,) not widened on curves because overhangs caused no problems on prototype radius (NYC never used articulated locomotives in road service on The Water Level Route.) This was pretty much the norm for US railroads up until the end of the steam era - but some routes had to be adjusted to allow for oversize locomotives and other situations peculiar to some specific locality.
- Present construction, UP (and others) - 21 feet (2 7/8 inches.) This spacing permits trains to pass crews working on a parallel track at higher speed, and also eliminates most of the problems associated with handling over-width loads.
As always, if you are interested in a specific prototype and era, it’s best to do some research into the standards in effect at the time and place you are trying to simulate. There was no “one size fits all.”
Chuck (modeling Central Japan in September, 1964)
What is the deal? Is everyone out there laying parallel track? This is at least the third time this has been asked in the past 2 months.
http://www.trains.com/TRC/CS/forums/885229/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/1121185/ShowPost.aspx
http://www.trains.com/TRC/CS/forums/1120617/ShowPost.aspx
Most HO “module standards” I have seen put the parallel straight tracks on 2" centers. When one goes into a curve that usually is made wider. The tighter the curve the further apart the to tracks need to be. Hence the standard sectional track is made at 18" and 15" for a 3" center.
At the club we have 2.5" centers in the yard so that we can see the reporting numbers down between the cars and so we can get our fat fingers in between to easily take cars off and put them on.
I decided on 2" on my double track main line but I wanted to keep my spacing even between tangent and curves if at all possible since I like the look. My curves are either 42" and 40" or 40" and 38". I operate full length passenger cars so I built a test track (with cheap brass flex track from a swap meet). I found I could stay with 2" spacing thru my curves and run passenger trains on both mains without snagging so long as I did not go below 38" curve. When I tried 36" and 38" it was way too close for comfort. It almost touched. I am pretty sure they would touch if I want to 35" or 34" radius curves. Any curves tighter than 36" and I think you will want to increase the 2" spacing for curves.
Dave Nelson