I have an elevated track section for my CTA station. I made the trusses to support the track by first designing them with CorelDraw and then cutting them with my Glowforge laser cutter.
The straight flat trusses were fairly easy to do. The straight "sloped" truss used to get the track elevated to the height of the Subway car doors was a bit trickier.
However, at the end of the elevated truss there are several 072 Ross curve tracks that require "curved trusses" that sloped back to the lower elevation of the track run. That was the challenge!.
Designing a perfect 072 curved truss was done using CorelDraw's "fit objects to path" command. This allowed me to create the necessary nodes and intersection points along the 072 circle section designed around Ross' 072 curve track to make the truss pattern. In Corel, I first created three circles on the same centers with diameters of 74", 72" and 70"respectively. Now I need to have circle segments that matched Ross' 4 tracks per 90 degrees. So I created a line longer than 3-1/2" and told Corel to fit that "line" object to the 72" circle path 15 times. Corel then bisected the circle into 16 segments; I only needed one. Next, I created a line 2" long and told Corel to fit it too to the 72" circle path this time 127 times.
Now I had each of the 16 segments split up into 8 wedges that cross the 74" and 70" circles as well. Since I only wanted ONE of the 16 segments representing ONE 072 track section I deleted all the rest of the lines and the 70" circle. Splitting the two outer (74" ) and inner (70") circles at the ends of the one segment I wanted, left a single segment that now had intersections I used to create the top and bottom trusses by connecting the intersections in the truss pattern of X's I wanted.
the result after cutting looks like this:
Fits Ross' 072 curve perfectly.
The small squares shown above were also fit around the path and are used to support the interior truss braces on the inner and outer chords as well as nine(9) Xs in the interior that progressively reduce in size to accomplish the slope I wanted. See below;
This same technique could be used to design and fit ANY Ross' curve tracks or of any curve tracks of any known diameter.
