The mechanical design of the K 'n G Railplex started with clearly stating goals and then making trade-offs and compromises to achieve a practical train layout.

We wanted a train layout demonstrating running multiple trains on one track using a "block" control system; at least six trains seemed about right. This meant enough track area to hold six trains.

We wanted the multiple trains and automatic operation aspects to be easily noticed. Visitors had to be able to watch as trains traversed the entire layout. We needed a "look down on" table height.

We would take the layout to train shows. Train show table spacing suggested the layout should be no wider than about ten feet. "Take" meant it had to be in sections and transported with an available standard-size, short-bed, pickup truck. Sections couldn't be longer than the truck bed. Some panels would have to fit between wheel wells, others could be as wide as the truck bed above the wheel wells. The conventional sizes of building materials also had to be considered.

"We" meant loading and setup by two guys, getting on in years. The weight of each section should be reduced as much as possible.

Running multiple trains using a "block" control system requires track blocks to be at least "coasting distance" long. Sections should be at least "coasting distance" long to avoid excessive wiring between panels. "Coasting distance" is about five feet for postwar trains running at a brisk pace. So, sections should provide at least five feet of running room.

Track would have to be joined at panel breaks each time the layout was setup. After some investigation, we decided only O-Gauge tubular track could withstand repeated setup and tear down cycles. Running six trains requires a reliable track design and, especially, reliable track switches. We decided on a minimum of O-72 curves and O-72 track switches.

Block control and automatic operation would need controllers and more than a usual amount of wiring. It would be convenient if wiring most could be accomplished from the top of the layout and if controllers could be easily monitored while watching trains.

After a lot of design trials, the following panel arrangement and track design resulted.

The portable layout has eight panels. The four center panels are 3' 4" wide and 5' 5" long; they fit between the wheel wells of the pickup truck. The corner panels are 4' wide by 5' 1" long.

The track design has 234 feet of track with thirty-eight independent blocks. Curves are O-72 and O-96, with some O-54 curves in the center most "work" loop. There are twelve O-72 track switches. Most of the thirty-nine track joins at panel breaks are with straight track sections. There are twelve track sections and three track switches that are joined during setup.

Train operation is smooth and reliable: track switches are arranged so trains make smooth curve transitions. There is only one "S" curve, from the inner loop to the work loop.

Wiring to the track and panel interconnect cables would be under the main part of each panel. A "wiring well" area was designated for each panel. This area would contain the controllers and wiring among them. A removable cover provides access. The track design (mostly) avoids this area.

We used "AutoSketch" to design the panels and produce a dimensioned drawing that showed exact sizes of each piece of the panels. Additional supports were added to carry the weight of trains. We could also use the drawing to help lay the track.

We decided to employ a "truss" design for panel members. The outside trusses are 3 1/2" high, consisting of two "rail" sections with a hardboard center part. The truss between the wiring rails is also full height, but with a wider top rail to better allow fastening the track surface to the truss. Support trusses are reduced in height and only have a top rail piece. This saved weight and allowed for table legs and for more conveniently running wires.

The end parts of the trusses are different, depending on how the truss is joined to other trusses. The trusses on the "operator" side were made with a relieved area to hold operator controls.

To facilitate construction each panel was identified with a letter, A - H, and each of the 64 trusses numbered. A diagram shows each panel and its component trusses.

The 64 trusses are made of 258 separate pieces; that was a lot of pieces to keep track of. The drawings were used to make a list of each truss showing its form and dimensions. The list was organized to collect identical pieces together so they could be made with the same tool setup. Working from the list was easier and more efficient than construction from just the drawings.

With the design completed and organized, we were ready to construct the K 'n G Railplex.