Designing an S curve crossover in Templot

[Dungrange]

Okay, I'm trying to get to grips with Templot and what I want to create is a template for a trailing crossover on an S curve.  The image below broadly indicates what I am trying to design.  On the left are two tracks: the lower one being the bi-directional branch line to the rest of the network; the upper one is a goods loop, formerly part of the down line, but now used to stable freight stock outside of the station.  On the right are three tracks, representing a bay platform, the former up line platform (now a terminal road) and the former down line platform (now also a terminal road).

 

 

The 'mainline' is effectively the route from bottom left to middle right.  This needs to be an 'S' shape with radii of approximately five or six feet.  I then want to offset a second parallel track (top left to top right) and fit a trailing crossing (B8) between these two tracks.  The crossing would therefore ideally be somewhere on the transition between the left and right hand curves and the point of contraflexure is probably within the middle turnout.  Whilst I can slide the location of a turnout along a curve and seem to be able to insert transition curves, I'm not quite sure where to start with my design. Starting from the left, I think I am looking to insert an easement from straight; a constant radius (left hand); an S curve reverse transition; a constant radius (right hand); and finally an easement to straight.  Once I have this with the correct amount of horizontal displacement, can I insert a turnout into this length of plain track and slide it from one curve to the other through the transition?

 

I'm sure I'll have plenty more questions as I try to get this design to work.

[martin_wynne]

Hi David,

 

For your "main line" you need 3 templates -- easement from straight, S-curve transition, easement back to straight. Then to create the upper tack you would use the make double-track function from each one of those.

 

You can't slide a turnout across a template boundary, you can roam it only within a single template. However, if you can't resolve this by adjusting the position of the template boundaries, it is very easy to align a separate truncated half-turnout onto each side of the boundary to get the desired result.

 

For a double-track crossover on a transition curve, it is better not to use the make crossover function. Instead make double track as above, insert a turnout into the new track, and then roam it into alignment with the first turnout.

 

This is all straightforward for experienced Templot users, but a bit too complex for a detailed reply on RMweb. If you ask again on the Templot Club forum, I will reply in more detail and make a bit of video showing the process. Templot Club is at http://85a.co.uk/forum/

 

regards,

 

Martin.

[martin_wynne]

Hi David,

 

An alternative would be to use a slewed template. This means it would be all one template:

 

 

This has the advantage a turnout can be inserted in it and roamed anywhere within it.

 

I don't normally recommend slewing a turnout because it is difficult to know the exact radii within it.

 

Martin.

[Dungrange]

Thanks Martin,

 

I'll give your original suggestion a go first.  Set the 'straight' at either end of the baseboard first and create two easements and then fit the S transition between these.  I'll see how that wrorks out first and I can take it from there.  If I run into problems with splitting the turnouts across templates, I may give your slewed suggestion a go.  To be honest, I'm not too concerned about knowing the minimum radii.  The track will be 4-SF and although I'm targeting a minimum radius of around five foot, but I'd be willing to accept a little less provided it wasn't less than around three feet and looked okay.

 

The key is to find the time to actually learn the functionality that I need.

[martin_wynne]

Set the 'straight' at either end of the baseboard first and create two easements and then fit the S transition between these.

 

Hi David,

 

It will be easier to create the easements last.

 

Here I set the original templates straight and parallel. They could just as easily have been at a slight angle or gently curved. Then I created an S-curve transition template and positioned it between them. It needs to come close to the original templates, but to be offset from them slightly:

 

 

 

Then use the make transition function to create the easement. Check that the transition zones do not overlap, and if necessary go back and adjust the S-curve closer to the end template until they don't:

 

 

 

Now shorten/extend the template boundaries to be clear of the transition zones, and then insert your B-8 turnout. Roam it up to the required position, truncated at the boundary:

 

 

 

Insert another B-8 turnout into the S-curve template:

 

 

 

and snake it back into alignment with the first one:

 

 

 

Then do > blank up to peg menu item truncates it at the required position:

 

 

 

Now you are ready to make the crossover. Create double-track from each of the templates, insert another B-8 turnout into the new S-curve, and then snake it into alignment at the crossover road:

 

 

 

Blank it up to the peg as before, and adjust the overall length as required. Finally insert another B-8 turnout in the end template, and roam it into alignment:

 

 

 

With the required result -- a crossover on an S-curve with the turnouts split across the template boundaries:

 

 

 

The key is to find the time to actually learn the functionality that I need.

 

 

If you ask again on Templot Club forum, I will make a screen video showing all these clicks and adjustments, and make a more detailed reply.

 

regards,

 

Martin.