I finished my 4X8 Layout in the garage and now have moved on. I have taken over the basement. My layout will be HO scale. I am going to have a U-type layout. Lengths are 12X20X12. I am constructing the benches 2ft X 4ft sections. The question I have is at the end of each 12ft section will I be able to fit a 24" radius turnaround or do you think I need to make the last 4Ft section larger. I am using SD70MAC BNSF train with 50' cars. Do you think that 12X20X12 is large enough for HO Layout? 4X8 sure wasn't.
If you are going to use the conventional (proper) method of making a true radius curve, you are going to measure the radius from the pivot point to the centerline of the tracks. This means, necessarily, that your outer ties are going to move in an arc that is about 3/4" further out. So, for a true diameter, which is what you must measure for this loop, you must double the radius of 24" and add twice 3/4". This totals 49 1/2" (49.5 inches). You will need clearances outboard of the outer rail for parts of each car and locomotive that overhang the outer rail. I would not want less than 2". Now you are looking at 54" of needed breadth in order to accomplish what you want to do. That is well past the four feet you have in mind.
