I have come up with the figure in the neighborhood of 24'-25' feet for the length of through tracks to hold 10 passenger cars (figuring 12" each) plus the turnout clearance for #6 turnouts. This makes it tough to get into a 12' x 13' room because it uses up two complete walls. Am I anywhere close on the length needed for these though ladder tracks?
For a ten car train, you need 10ft plus the clearance length of two #6 turnouts, total 12ft. So where do you get the 24 foot from? Are you planning to put these tracks end to end? Or store two trains end to end? What about reserving one side of the room for the storage tracks, and building shorter parallel through tracks?
What kind of layout are you planning/building? Without some sense of your overall plans, it's tough to understand your problem, let alone suggest solutions.
I'll toss one out anyhow: Unless you stand well back, you can't see a complete 10-car passenger train in HO, certainly not in a 12'x13' room. So planning for such long trains in such a small space isn't needed. You can easily get away with trains of two locomotives + 5 cars, or about
6-1/2 feet. If you plan the layout as a series of scenes, the view blocks (both physical and psychological) that separate the scenes will add to the illusion of a long trains, since you will find it difficult to see both ends of a train at the same time.
HTH, if not, come back with more background to you problem.
12" would be 87' in H0. Yeah, about 90' is typical for passenger cars. One *could* 'cheat' and use shortened cars -- Athearn used to make passenger cars that were about 70 scale feet long -- not truely scale correct, but could be used as part of "selective compression" to make things fit better in a smaller space)... Or use shorter trains -- 5-6 cars rather then 10 -- another "selective compression" trick.
Wolf hit the mark with his statement that the length of train one can view in a single glance/scene is all that is required. An exception might be one of those interminable goods trains one meets at level crossings when one is late. The length one can see in a scene is dependant on how far away one can stand from the track. Generally we build layouts to fill the available space and so have minimal human space very close to the tracks. The viewable length is usually about 1-2m. One can build view blocks such as stands of trees, raised terrain, city buildings etc to break the view where there are long open stretches. For my layout I set the maximum train length at 2.5m (8') As I run 1932 German trains my passenger coaches are shorter than US. (240mm - 9") One difficulty is that there are occasions when I can't fit one of each relevant type of coach into a train: 2 locos/Post/luggage/3rd class/
2nd/3rd. For goods trains (freight) the prototype limit was 100 axles - the model limit is about 50 axles. The main feature of the layout is banking trains up a steep section of main line - adding banking locos means the trains have to be shorter so I get into the odd situation where the heavier the train represented, the shorter it is. Still, the problem is largely in my head because the 2.5m length is much longer than can be viewed at one look.