End Module Ideas

	Name "The Big One" Dimensions 48" x 30" Curve Radius 21", 19-1/2", 18" Track set-back 5" To Connect Two standard 24" modules back to back, with a 2" spacing between modules to accommodate skyboards and bolt heads. Comments This design is the logical extreme on the large end of the spectrum. The broad curves are all at or above the NTRAK minimum 18" radius. As drawn, the end is 48" long to load conveniently with other standard 4-ft modules. We could easily decide to expand the length to the full 50" so it is flush with the front edge of adjacent modules. Advantages Broad curves which will not limit any rolling stock or locomotives, generous track set-back at mid-point of curve for safety. Disadvantages Large module, potentially heavy, non-standard height makes transportation a little more complex, leaves a 1" overhand at the front of adjoining modules.
	Name "Standard" module in size and set-backs Dimensions 48" x 24" Curve Radius 16", 14-1/2", 13" Track set-back 4" To Connect Two standard 24" modules back to back, with a 2" spacing between modules to accommodate skyboards and bolt heads. Comments This design is slightly smaller than "A", transports conveniently with standard modules, and maintain the standard 4" set-back at the midpoint of the curve. Curve radius is 16" on the outer curve, which we have found operationally satisfactory on our old end loops. Advantages Slightly smaller, more manageable module size, reasonable curve radius, with the 4" standard track set-back for safety. Disadvantages Still a significant sized module in terms of size and potential weight, curves begin to limit operational reliability of some rolling stock and locomotives, leaves a 1" overhang at the front of adjoining modules.
	Name "The Compromise" Dimensions 48" x 24" Curve Radius 18", 16-1/2", 15" Track set-back 2" To Connect Two standard 24" modules back to back, with a 2" spacing between modules to accommodate skyboards and bolt heads. Comments This design increases the curve radius to NTRAK minimum on the outer line and just below yet still generous on the two inner lines -- at the expense of track set-back at the midpoint of the curve. We might consider a Plexiglas safety wall screwed to the module edge at this location, similar to what we have used on our old loop modules -- or hill scenery which would contain derailed equipment from falling off the module. Advantages Slightly smaller, more manageable module size, slightly larger curve radius as large as NTRAK minimum on the outer line, most rolling stock would operate and look reasonable on all three lines. Disadvantages Still a significant sized module in terms of size and potential weight, inside curve might limit operational reliability of the largest locomotives, only 2" safety margin at the end set-back (unless we install a barrier), leaves a 1" overhang at the front of adjoining modules.
	Name "Bridge Modules at the Rear" Dimensions 38" x 24" Curve Radius 15", 13-1/2", 12" Track set-back 5" To Connect One standard 24" module and one standard 12" wide bridge module back to back, with a 2" spacing between modules to accommodate skyboards and bolt heads. Comments This design considers the other major layout option we have debated: using a 12" bridge module at the rear of the layout. We have at least two 4-ft. bridge modules in our club already, with two more bridge-style crossover modules under construction. Using bridge modules at the rear significantly reduces the logistics of module hauling, at the expense of curve radius (unless we choose a larger design above). Advantages Significantly smaller module with proportional reduction in weight and hauling complexity, curve radius still comparable to those found on home layouts, generous track set-back at end, module sized to sit flush with the front of adjacent modules. Disadvantages Curve radius beginning to impact operational ability of larger locomotives and reliability / appearance of longer rolling stock.
	Name "The Compromise -- Revised Slightly" Dimensions 41" x 24" Curve Radius 16-1/2", 15", 13-1/2" Track set-back 3-1/2" To Connect One special 36" module (Drew's grain elevator module set) and one standard 12" wide bridge module back to back, with a 2" spacing between modules to accommodate skyboards and bolt heads. Comments This design is a modification of "D" above to accommodate Drew's extra-wide grain elevator module (36" wide with 3" extra at the front and 3" extra at the rear compared to at standard 24" module), resulting in slightly larger radius curves and a near-standard 3-1/2" track set-back at the midpoint of the curve. The diagram is also drawn with a standard 24" wide module placement for comparison. Advantages Can accommodate slightly wider modules, with a proportional increase in curve radius and one line above our club preference 16" radius, still near-standard track set-back at the layout end. Disadvantages Starting to get a larger and heavier module, curve radius still somewhat smaller than preferred on the two inside lines.
	Name "The Minimum" Dimensions 30-1/2" x 20" Curve Radius 12-3/8", 10-7/8", 9-3/8" Track set-back 3-5/8" To Connect One standard 24" module back to back with a special 6" wide bridge clamped to the rear of the standard module skyboard. Comments This design is probably the logical extreme at the small end of the spectrum -- and included for comparison -- by far the smallest module, and probably the lightest, with very tight curves, but also the easiest to set up a layout because the special bridge modules at the back simply clamp onto standard modules with no need for their own legs. Advantages Significant size and weight advantage compared to the other designs, in addition to the ease of layout set up described above. Disadvantages Very tight radius curves having significant limiting effects on long rolling stock and large locomotives (six-axle locos only on outer line probably, only nimble four-axle locos and steamers with blind drivers on inner lines), need to construct special 6" bridge modules.

Drew's comments:
I want to have end turnback modules at home so I can work on and run the modules I am currently building as well as have a place to operate my longer passenger equipment. If we can agree as a club on what design we want for our small club layouts, I would be willing to build a pair of end modules to that design for use at home as well as club use when needed. (Hence Design E to accommodate my under-construction 36" wide grain elevator module set.)

I think I prefer Design C because it allows us the most flexibility in designing a small show layout and provides a larger-radius compromise on a (smaller) standard size module frame. We could use back-to-back standard modules if we wanted to (giving us a two-sided layout for public viewing should that ever be desirable) and could also use 1-ft. wide bridge modules to the rear if we preferred the relative ease of hauling smaller, lighter bridge modules (which is the main motivation in considering using 2 end turnback modules instead of 4 corner modules). We already have two 4-ft. bridge modules and at least one 2-ft x 1-ft bridge module in our club inventory, with two additional 4-ft bridge modules coming on line soon with crossovers between the lines -- and bridge modules are relatively easy to build and scenic.

I agree that Design D is a significant savings in size and weight for simplicity of hauling and would be willing to go with the wishes of the club if we decide to commit to bridge modules at the rear. Tom Newell and I played with numbers one night and decided that we could build a pair of special bridge modules (or three) with at least 1 staging track per line in addition to the through track, and probably 2 staging tracks on the outer line. This brings additional operating possibilities to using bridge modules to the rear of a small public layout. If we settle on committing to bridge modules at the rear and the smallest practical end modules (Design D), I would (selfishly) prefer Design E because I could use it at home with my grain elevator module set -- if the club accepts my offer to build the end modules for use at home and shared with the club when needed. (Then we get into the logic that if we are going to build a 41" long module, why not just build a 48" long module for the extra flexibility at not too much additional weight and size.)

Years ago, I built turnback ends to design F. They worked well with the limitation of not using large steam locomotives and accepting that longer rolling stock looks pretty unprototypical on the sharp curves. The 6" bridge modules are easy to build and don't require wiring if you take some care with the rail joiner contact. I wouldn't recommend them for public shows where we want our equipment to look somewhat decent on curves, but they sure are easy to move!