Layout Givens and Druthers

One of the first model train books I wore out growing up was John Armstrong's Track Planning for Realistic Operation. John Armstrong's Givens and Druthers were the basis for many of his track plans. In my professional life, I teach Design Methods, and we do much the same thing, by formulating design requirements. Design requirements are a combination of constraints (items that are nonnegotiable, i.e. the Givens) and criteria (items that are desirable, i.e. the Druthers).

In my previous post, I discussed the available space and described the necessity for a phased construction approach. These all relate to significant design constraints. But what other constraints are there?

1. Well, one primary constraint is that I want a layout that can host operations. I enjoy operations a great deal, and one of the reasons I have fallen away from building modular setups, is that I enjoy operating a lot more than simply running trains around a layout. I prefer operations to simply parading trains around a layout. In particular, I enjoy dispatching and yard operations. Local switching and over the road running is less of a priority.
2. The layout should be operable by a crew of 1, but can also be enjoyed by a larger crew. 
3. I want the layout to be self-re-staging as much as possible.

I have a lot more criteria to the project. These include:

• Scale - N is my preference, and I have collected a lot of rolling stock in N scale. I have also operated on several N scale layouts and I have found that operations in N scale are quite enjoyable. Would I consider a shift in scale - yes, but only for a definitive benefit.
• Gauge - Obviously, I have been considering both standard and narrow gauge. I have had a particular interest in Nn3 for the last 25 years. I have even built multiple Nn3 modules, and I am convinced that operations are equally viable. More recently, I have developed an interest in other scale/gauge combos, including Nn2 (N scale on T-gauge track), Zn2 (Z scale on T-gauge track), and HOn2 (HO with Z-gauge track). My father has recently gotten into On30, and I have to admit that there is a certain appeal to that as well. Particularly the Bachman geared locomotives. This decision will primarily affect the style of operation.
• Scenery - While Operations is my priority, the best operations oriented layouts are still often recreations of recognizable scenes. These scenes provide the pauses between operations tasks. These pauses provide both a sense of distance and time between the tasks. Thus, I do want to capture scenery for the in-between places. Further, since one of my passions is dispatching, distance is crucial between sidings, and furthermore multiple sidings are essential.
• Era - Probably a modern era layout, 1987-1996 is one particular timeframe of interest. I do want to be able to recreate backdated scenes and run out of era equipment occasionally.
• Train types - Given the era, I am looking primarily at freights, but I will host Amtrak, and some special passenger trains on a regular basis.
• Track Standards:
• For N-Scale Standard Gauge, I plan on using the following: Mainline - Code 55, Minimum Radius 18", Easements on Curves below 36", Grades per prototype, Mainline Primary Turnout #10, Secondary Turnout #7, yards and industries #5 which match the new Atlas Code 55 offerings. Whether I will use Atlas or Peco is undetermied, but handlaid turnouts are a viable consideration. Grade separation, 2.5" (tentative). Branchlines may use tighter radii, down to 15", and spurs may go down to 12" as may rarely used tracks, such as engine terminal or wye trackage. Target train length of 168" for unit trains, 138" for general freights and 100" for passenger trains.
• For Nn3, 10" minimum radius, 12" preferred. Turnouts of #5, #7 and #9. Code 55 and Code 40 rail.
• Multideck design is okay, and in fact is likely, with a target deck separation of 12-14".
• Grades - This depends upon the prototype to be modeled, because I would like to replicate the grades if possible. However, I will still need to do some testing to determine the impact of curves and grades on engine power.
• DCC Operations if at all possible.
• Duck-unders - Nod-unders are okay, Hinged sections are okay, I would prefer to avoid most duck-unders or liftouts.
• Walkaround Design preferred.
• Aisles - Target of 48" near yards, 36" Nominal, 28-32" okay, and 24" only for pinch points.

I am sure that there are others I should think about, but these are a pretty good start.