28" and 30" double track turn.

[jcgisel]

Question about subroadbed in turns. I am new to this sight and I think it is great. I am on my third layout and am trying to plan on how to do a curve with 2 tracks at a 28" and 30" radius. What size should I cut the subroadbed and could I make the curve tighter for passenger cars?
Thanks.

[camarokid]

Cutting the subroadbed depends on if you want two separate beds or just one that covers the two tracks. 3inch wide beds are usually the norm for one track. For double track curves you will need at least a 2 inch center to center radius or more depending on the length of the engines and cars you intend to use. Two and a half would be better. This makes a 12 inch wide curve you would need to mark and cut out. I wouldn't make the curve tighter because then your passenger cars would have too much overhang and not look realistic when viewed from the top and front or rear from where you are standing when viewing. You could also lay your track out and put your longest cars on each track to see if they touch each other. That way you will know how much center to center you will really need. Hope this helps. Don't forget to do the same with your engines. Enjoy.
Archie
P.S. Maybe 12 inches is too large. You could go with 9 or 10. Just be sure it's level.

[Anonymous]

I just had to re-lay staging yard tracks that were 28" and 30" I had to pull the 30 out to 30.5 to make sure the passenger cars will clear. I tested with Cab Forwards running past each other, no problem, passenger cars... problem (go figure!!)

2.5" on center is good. I have cheated that with larger radius curves, but always check clearances with long (80'+) passenger cars and any large rigid wheel base locos that you plan to run.

Get an NMRA guage as well to check clearances between track and other obstacles such as posts etc. I usually add at least a half inch to gauge clearance just to be safe. As far as how wide the sub-roadbed has to be, it is up to you. There are spots on my layout where space is tight and track is right at the edge of the roadbed (In hidden staging). In any tracks along the edge of the layout plan how you are going to trim the edge of the layout and cut your sub- roadbed accordingly. I have had to go back later and scarf stuff together along the edges to make a nice fascia after cutting boards off too short.

[2021]

Interestingly, I'm just starting to lay out the same type of double track curve. I am using 2" track spacing on the main line, but on the curves will use 27 1/2 and 30 inch radii. I use the smaller inner radius because of the extra space (one inch - big deal) of the larger radius taking up more of the outer edges and increasing the overall diameter. Let us know how it works out. Good luck.
Ron K.

[rrinker]

DEFINITELY go to a 2 1/2" difference. I thought I would be safe with 30 and 32" curves, but a lot of my father in law's passenger cars sideswipe on those curves! Luckily we discovered this BEFORE laying the track, so I altered the plan and now there is enough room.

--Randy

[jcgisel]

Thanks for all your advice. I will definately use 2.5 spacing. I am hoping to get the two lines up by the end of the weekend.

[rexhea]

2.5" should do the trick. If you have articulates such as a Class A, be sure to check it out with other long cars on the curve in question and other curves. There is a heck of a cab swing with them, more so than a passenger.