Diverging Mainline Pointwork

[Newmodeller96]

Hi, 

 

I have come back to my layout after a while away. 
 

I am working on one half of my layout. It’s 00 gauge and is to be set from the 80s to modern day in southeast London, so looking at dmus and emus mainly, but with some scenic freight aswell. 
 

I have a medium size straight roughly 3m down one side of my layout that I would like to use to create the look that the “mainline” goes off scene and onto my helix and then my “branch line” stays to the back of the scene and carries on to the smaller station at the side of the layout. I was possibly thinking of there being a “storage yard” or “line maintenance depot” on the front of the board so there would be lines coming off the line and down to the front of the board too.

I did have my head set on the helix at the right end of my layout however I am happy to change this to make it work for layout. 
 

I have attached a basic drawing of my layout. The station at the bottom is already laid. The outer line is the clockwise “down” and the inner is the anticlockwise “up”.  I hope this makes sense to someone. 
 

Thanks
 

 

[njee20]

What’s the question?

[Newmodeller96]

19 hours ago, njee20 said:

What’s the question?

basically a good way to add a diverging line and a goods/yard of some kind in the upper area of the picture. 

[Chimer]

There are basically two ways to arrange the junction and helix as I think  you want it .... a burrowing junction (top) or a more normal double junction using a diamond.

 

 

I've assumed you want the helix to exit down the left hand side of the layout, but don't know  what you want to do with the tracks after that.  Does it actually need to be a helix, with all the accompanying complications?

 

I can't see how you could possibly arrange things so the helix is at the right hand side except by mirroring the whole thing, which wouldn't have the tracks diverging in the way you have described.

 

Either way, the main lines need to lose height quickly (at least 3") to get under the branch before the start of the helix.  If you used the simple double junction with the main lines descending behind the branch lines instead of in front of them, that would ease that problem, and make it easier to arrange access to the yard you also want on this side of the layout.

 

Hope this gives you something to think about ....

 

 

 

 

[TravisM]

On 16/12/2023 at 13:49, Chimer said:

There are basically two ways to arrange the junction and helix as I think  you want it .... a burrowing junction (top) or a more normal double junction using a diamond.

 

 

I've assumed you want the helix to exit down the left hand side of the layout, but don't know  what you want to do with the tracks after that.  Does it actually need to be a helix, with all the accompanying complications?

 

I can't see how you could possibly arrange things so the helix is at the right hand side except by mirroring the whole thing, which wouldn't have the tracks diverging in the way you have described.

 

Either way, the main lines need to lose height quickly (at least 3") to get under the branch before the start of the helix.  If you used the simple double junction with the main lines descending behind the branch lines instead of in front of them, that would ease that problem, and make it easier to arrange access to the yard you also want on this side of the layout.

 

Hope this gives you something to think about ....

Having worked for SouthEast Trains in the past, I would say that the top diagram is probably more prototypical as railways wouldn’t like to have one route blocking other on high density routes, unless it was absolutely necessary.  They would want, where possible, a seamless flow.  I hope that makes sense?

[Chimer]

I've always liked the idea of modelling a burrowing/flying junction, but they do take up a lot of space to do properly with manageable gradients.  Would be a bit odd in the OP's vision, as it is his main line which has to do the burrowing, and the gradients would be brutal if restricted to the 3m space.  If the junction could be positioned on the board at the right of the room it would be more feasible - this is of course true for either junction option.

[ISW]

On 14/12/2023 at 19:07, Newmodeller96 said:

I did have my head set on the helix at the right end of my layout however I am happy to change this to make it work for layout. 

That was the original plan for my layout, until I discovered just how much space they take up! And I have a room roughly 5m x 4m.

 

I decided that 'ramps' were a better (space saving) option, and I managed to install them with gradients of ~1in45. This 'might' help you to visualise the arrangement of the Upper Level:

 

The ramps disappear / appear on the Upper Level at Connection 1 & Connection 2a. The 'trick' is that the Upper Level is not 'level', but falls ~100mm in a full circuit, allowing the tracks to pass underneath themselves (at Connection 1). I'm not the first to have done this, as I copied the idea off the Crewisle layout.

 

Ian

[DCB]

On 14/12/2023 at 19:07, Newmodeller96 said:

 

 

 I can't see how the plan will work with a single Helix.   To get up and down you need two helix or some very complicated  approaches as the inner track has to start one whole level above the outer and finish one whole level below if the helix is to work for trains in both directions.

There has been at least one layout substantially completed which could not be operated without lifting stock off the tracks on the visible section due to no one thinking how where trains would run to. likewise there is no real way to get a visual continuous run over a helix without it dominating a layout

With a single helix you need to reverse the trains on the visual section, ideally a terminus and then reverse the trains again on the lower level.

[Bittern]

On 27/12/2023 at 11:53, DCB said:

With a single helix you need to reverse the trains on the visual section, ideally a terminus and then reverse the trains again on the lower level.

I'm sure I've seen an American design ( I'm visualising Model Railroader-style diagrams) where the inner track continued for an extra half-turn and then crossed back to the other side of the board while the outer track went straight, so that the helix effectively spliced into one track of a double track line, but I can't remember how the layout compensated for the unequal staging space for each direction.

 

A variant of that would be to put a double junction at level -1 relative to the main line on level 0, then have the curved route run under the main line on the level and rise up inside the main oval, while the straight route rises up to level 0 outside the main oval. The downsides of that, apart from congestion on the helix, are that the level curve needs to be outside the helix (adding an extra double track width to the circle) and you need a return loop on the lower level (though that could go under the helix).

 

TBH, if you've got a continuous run and can arrange access in a way that doesn't require a lifting section or duck-under (eg a section of layout on a trolley, or a loft/cellar), an around-the-room helix seems like a more practical solution.

 

@Newmodeller96 Where's the entrance? Whatever you do on a lower level needs to keep clear of that.

[Newmodeller96]

On 28/12/2023 at 12:29, Bittern said:

I'm sure I've seen an American design ( I'm visualising Model Railroader-style diagrams) where the inner track continued for an extra half-turn and then crossed back to the other side of the board while the outer track went straight, so that the helix effectively spliced into one track of a double track line, but I can't remember how the layout compensated for the unequal staging space for each direction.

 

A variant of that would be to put a double junction at level -1 relative to the main line on level 0, then have the curved route run under the main line on the level and rise up inside the main oval, while the straight route rises up to level 0 outside the main oval. The downsides of that, apart from congestion on the helix, are that the level curve needs to be outside the helix (adding an extra double track width to the circle) and you need a return loop on the lower level (though that could go under the helix).

 

TBH, if you've got a continuous run and can arrange access in a way that doesn't require a lifting section or duck-under (eg a section of layout on a trolley, or a loft/cellar), an around-the-room helix seems like a more practical solution.

 

@Newmodeller96 Where's the entrance? Whatever you do on a lower level needs to keep clear of that.

Thanks for this. The entrance is in the Bottom left that is a removable section. 

 

I think I have worked out the design now as have made it that both lines are able to go "off scene" and then they become 1 line for the helix down into the lower fiddle yard.