noted - thanks Tim

A concept which is always on my mind, the "inverted return loop". It is an alternative to the the classic simple return loop (e.g. post no. 54) which is eating up 120 cm in terms of length. Depending on how clever it is incorporated, the inverted return loop can save vertical space while adding scenic interest. In addition, the inverted loop can accommodate longer trains than other arrangements, which is advantageous for somebody like your correspondent who wants to be able to run a 400 cm long freight (goods) drag. A spring switch (sprung point) is used which saves on electronics and maintenance, making a train enter the loop into the same direction. The returning leg can be positioned below or above the loop track, but I prefer the first option, allowing for a depressed scenery like a track bridging a river valley before graciously descending to the valley bottom (see last image). There are endless variations, as mirroring the setup, using wider curves or adding a station below the bridge. For simplicity, I focus on the minimalistic approach, but I allow myself the luxury of "easements“ with R9 curves at the beginning and end of the lower valley bottom curves which ensure that trains swing elegantly in and out of the curves. The basic concept fits on a 152 x 87 cm surface.

In either direction, the ramp from the highest point at the turnout - we don´t want any turnout on an inclined ramp - to the lowest point below the bridge is 200 cm. For a bridge height of 8 cm this equals a 4% incline. Like that the loop could serve to turn around trains coming from and going to the adjacent leg of a L shaped layout and /or shelf layout.

Tilting the above figure, space requirements change to 140 x 120 cm - see left side of below image. This can serve a rectangular layout which is extending to the left. When tilted, the the straight section on the ramp behind the turnout can be extended to ease the slope. Now the ramps have different lengths. Further the bridge can be curved, here with R5 curves. Then the surface equals 160 x 98 cm - see right side of below image.


When enforcing a against the clock running regime, thus descending on the shorter 220 cm and thus steeper ramp and climbing the longer and gentler 270 cm long ramp, the train has only to battle a 3% incline, which is quite generous. Here a scenicking proposal, mainly meant to conceal tight radius curves and the very nature of the return loop while at the same time creating a dramatic scenery.

I would be tempted to create a station or hidden storage yards (depending whether visible or not) on the underpass by having a 24671/2 pair of points each side - you could even use two pair to give three tracks with a bit of care.

R1-return-loops, the right one has the S-curve countered by a 24071 in the middle.

For smooth coach movements:
Somewhat condensed curved station throat without S-curves (and without curved turnouts), connecting each station track to either main line track, and creating room for wider passenger platforms.

Space saver for simple fun or nucleus for things to come.

Add a short stub track to the left, and you have a test circle with a wye for turning around a loco.
Extend stub length and you have a small terminus to which trains can return after running one or more loops on the circle, before continuing the trip into the opposite direction (after having been "turned" in the terminal).
Leave the shortcut away and you have a return loop (or half a dogbone).
Conceal the rear half of the circle and you have a realistically looking layout.
etc.

My first contribution involving a large radius curved turnout: A "curved" station throat without S-curves, allowing to access all station tracks from either of the dual mainline tracks. The track planner shows minor gaps, but a reality check proves that it is possible - see images.

And a flashback regarding my former Humbug-Dummtor layout:
Nesting curved 24671/2 turnouts "counter-balanced" with 24330 curve(s) for good looks and smooth coach swings.

Alternatively, one could employ 24107 / 24207 track pieces instead of 24206 ones in order to create a slightly angled arrangement, avoiding straight tracks in parallel to the baseboard edge which looks less „static“. As standard Maerklin geometry rules are ignored, track spacing is to be tested with coaches to ensure smooth train passes.

Don´t ask.

Can something similar be achieved with the 24771/2 wide radius turnouts? Yes, it can: A 24640 paired with a 24207 7.5 degree curve balances a 24430 R4 curve on the inner side. For obtaining the correct angle a 24306 5.7 degree would be ideal, but that one is too short. Luckily there is the magic C track slack.


Now, what could that be good for? A curved "Hosentraeger"-crossing.

Adding the outer portion: 24206 + 24215 on top and 24307 + 24206 + 24206 at the bottom of the crossing are joined by two narrow radius curved 24671/2 turnouts. The outermost gap is filled with 24064 + 24912 + 24064 pieces.

Just to prove that with the right dose of 24206 and 24224 pieces a full 180 degree 120 cm diameter curve can be achieved, thus good enough for a 4 x 8 ft table. Note: Floor tiles measure 20 x 20 cm.

P.S.: Lacking a simple 24640 crossing I used a 24624 double slip turnout for the photographs.

The entire posting was about the curved Hosentraeger core - see image. And I pride myself on developing the concept.


You are missing the point: There is indeed no practicality regarding the "final solution", which ain't one; only brainstorming; slim turnouts just shown for illustrating achievable dual track distance; *not* meant to be used, never ever.


- If you are referring to the 24672-24064-24912-24064-24671 sequence framed in red in below image:

Well, on the outside any curved C track turnout has a straight section between frog and switch points. The 24671/2 equals on the outer side a 24077-24130. 24077 is slightly longer than 24064. Thus travelling over a short 24064 straight followed by a wide R9 24912 is much smoother than over the outer portion of any curved turnout. I would prefer to do away with the 24064, too. Thus, any constructive solution would be welcome.

- If you are referring to any other straights: irrelevant (see my "practicality reply" above).

This question has totally lost me.

Edited by user 28 July 2017 16:22:26(UTC)  | Reason: Grammar

These ideas make a lot of sense if your railway replicates what they call CTC - Centralized Traffic Control where there are no rules for which way is the right of way - left side, middle side, right side on the main line, it does not matter.
However these double scissor cross overs make most sense when running two tracks into three, and vice versa - a lot of sense. (or even 3 into 4, or 4 into 5 etc etc.)

And in station environs and throats, they can make a lot of sense too, where the geometry creates loops so that trains can bypass stationary trains. In the real world, a plan like the one above would be appreciably elongated to whole train length loops.

regards
Kimball

I know this is a basic that has been already showed by nice people,
but you can see this as a reminder that could help :

R1 R2 curves with 64.3mm space




R4 R5 curves with 77.5mm space




Best Regards
Joël

I really like the innovative inverted return loop.

Here is another triangle / wye in R2 and one R3.