This is the next tutorial in the blog about how to use the new feature for laying roads, introduced in SCARM v. 0.9.24. This article will explain how to create exact straight and curved parts from the basic flex road section.
This is useful if you want to use the roads in SCARM like sectional track pieces and to make perfectly aligned roadway networks. The task can be achieved by using of the Toolbox feature for modelling of flex tracks.
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Use “Tools” > “Toolbox” menu command to open the Toolbox window and then select “Flex-tracks modelling” function from the drop-down menu. |
Let say that you want to build your road network using a custom straight section of 127mm (10″) length. To make such part, select the basic flex road section and place it on the plot. Now enter the length of 127mm (10″) in the “L” field of the Toolbox, press “+Straight” button and finally press “Fix” button – your straight part is ready. You can copy, paste and join it as long as you need.
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It is a good idea to make your custom straights to be divisible to the length of “IS approach” section for the current scale. Its length is equal to its width, has the same length as “Intersection” and is twice long than different “IS Adapter” sections. |
If you want a curved part with a given radius and angle, place the basic flex road section the plot, enter the radius and angle in “R” and “A” fields, press “+Curve” button and then press “Fix” button – your curved part will be done. Again, you can copy, paste and join it to form the needed curves and turns.
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When make your custom curves, consider using radii which are divisible to the length of “IS approach” section for the current scale. Appropriate angle values are 90, 45, 30, 22.5, 15 and 10 degrees. |
Working with exact straight and curved parts may produce some gaps and/or overlaps that are unable to join. If a gap occur in the route, use the basic flex road section to fill it. If there is an overlap in the path, remove one of the overlapping sections and fill the gap as described above. See the sample roadway plan in HO scale and download it form the links below. It is build with just 2 custom parts and the standard crossing, approaching and adapter sections.
The next tutorial will show you how to make a railroad crossing with the roadways in SCARM.
Sample project
Exact-road-parts.zip
See also
The Roads in SCARM – Part 4 – Custom Crossings & Junctions
The Roads in SCARM – Part 6 – Railroad Crossing
I just read the tutorial titled Part 5 – Exact Straight And Curved Parts. I was hoping to find a reference to Spline Easements for the transition from tangent track to (constant radius) curved track. Prototype RRs use them for obvious reasons and they exhibit greater realism and smoother operation on models. There is a good article by Armstrong on how to construct one using a “bent stick” or metal rule that is copied here: https://www.nmra.org/sites/default/files/d3b3.pdf
I would like to put this to use in the Garden layout I’m designing. How about adding a few “virtual” parts that represent a spline transition from tangent to R-1 thru R-7? Obviously they would be built using Flex track, but the plan would make the rest of the layout “fit” the plan.
Prototype RRs have used splines “for ever”, but car/truck highway designers considered the math to be too complex for field work, unless there was an adjacent RR to copy. That was true until programmable hand calculators were sold. Someone actually earned a Masters Thesis based on such a calculator program.
Fortunately, for us the bent stick is close enough and would be a terrific addition to SCARM!
Hello Gene,
Easements feature is a planned addition and will appear in some of the next versions of SCARM.
Thanks, looking forward to it.
Gene
I did a trial case using the 3-section “TEMPLATE” approximation of a 30-deg Tangent to G-R7 segment. Visually it looks very good. The big Oops is that the total length of the easement is about 84 inches!!! I would need to at least double the size of my back yard to accommodate using even a few!
PS: Your Flex track laying tool is terrific!!!
For a short-cut to Easement Splines, see my FB post for Foamer Gene and look for the post that starts “Using Spline Easements”