On the occasion, I would like to address reverse loop and dogbone designs, mainly from an operational - and in my opinion aesthetic - point of view. Albeit geared towards a North American audience, below illustrations apply also to European users.

The continuous main line in the form of an oval is the most familiar layout design. With some sophistication - as incorporating twice-around courses, reversing tracks, alternate routes or just a very large oval to avoid a racetrack shape and viewing a train chasing its own tail - the outcome can be respectable.

But then, a point-to-point scheme is like the real prototype with trains running from one terminal to another. Once a train reached its destination more or less excessive shunting is needed before the return trip, depending on wether a railcar or a loco hauled consist is operated. Under normal space (and crewing) constraints, only a short line can be modelled by most of us.


The situation can be eased by point-to-loop or out-and-back designs, both cutting terminal switching in half. A point-to-loop offers the illusion that trains - actually parked out of sight - seem to battle their way across long distances before returning eventually, but this concept needs - or wastes - a lot of (hidden) layover space in the return loop area serving as lazy man´s terminal. An out-and-back design makes good use of the return trackage (which is kept visible) by making it look like part of the main line, but there is a fault in the approach as a train passes only once through the stations along the way (while with the point-to-loop a train passes through each station twice).

As soon as a return or reverse loop or balloon is involved, the advantage of Maerklin „3 rail“ versus a 2 rail approach becomes evident: the absence of the polarity problem.


Now enter the loop-to-loop plan - see last layout schematic in attachment "8-8" above and layout schematics A and C in attachment "8-5" below. Terminal switching is completely eliminated. Essentially also a continuous scheme, but trains run back and forth in a prototypical fashion. If more than observing trains is desired, i.e. switching and servicing, a yard has to be place somewhere, either along the main line or at one of the loops (I opted for the latter).

Of course, elements of all of the aforementioned can be combined.


Reduced to a schematic plan, the design looks like: Yes, a dogbone.


Inspired by reality, prototype operations can be condensed in a plausible way based on a dogbone to replicate even heavy duty operations on a rather compact surface (as I did on my current layout).


Synopsis by the late US track plan designer John Armstrong (principles also applicable for European model railroading):

"Continuous versus loop-to-loop. The larger continuous pike is actually rather similar in its general character of operation to the loop-to-loop plan with a single through yard. Trains can operate of the main line without interruption if desired, and the impression you receive, if you watch trains at any one point on the line, is that of traffic moving in both directions over the railroad, just as it should. As fig. 8-10 shows, the choice may well depend on the nature and extent of your road´s business in commodities carried in open-top cars.“


Source: "Track Planning for Realistic Operation" / John Armstrong. - 3rd ed. (1998), pg. 105

Edited by user 07 February 2017 15:30:31(UTC)  | Reason: Typo