Wayne Roderick, 3rd Division, PNR, NMRA (life)

10/11/00 rev 04/07/09 Duckundr.jpg

My old friend Bill Wilt of the South Side Lines in Nyssa OR has gone on to that big railroad in the sky, but he left me many good memories. One piece of his advice, I foolishly ignored and came to regret was: "Do not build duck-unders into your layout- you will regret it" How right he was! As the years progressed, nature took it's toll and while some of my guests couldn't reach all parts of the layout, I seemed to get around OK. Eventually I suffered some wear and tear problems and spent several periods where access was difficult or impossible. Today, those access problems have been banished.

OK, how do we get around it. Assuming that you've done everything in your design to avoid a human/track grade crossing and you still can't avoid it, let's see how we done it on the TSL.


Many years ago, when the house was populated with youngsters, the TSL was running out of real estate and we needed desperately to expand the market (needed a long mainline). To get the needed right-of-way around the perimeter of the adjacent family room that was used for TV and other activities I had to assure the real-estate manager (REM), AKA wife, that I wouldn't obstruct access to the room. The track making two loops around the room on a twelve inch wide right-of-way would cross the doorway at two levels, about 37" and 48" from the floor. Much too low for a duck-under and you can't have the kids fooling with delicate lift bridges. Besides the REM would not tolerate it.

I had two Dutch doors in the home, one into the railroad room and one at the top of the stairwell. A Dutch door is cut in half so the upper half can be opened separately from the bottom allowing airflow and communication while stopping passageway. In this case, like the existing one into the railroad we install only the bottom half, leaving the upper open- and now we have three.

Door Overall

With a coffee cup in one hand and a loco in the other, a single fingers is used to pull the door open for entry into the family room. There are no latches or devices to operate, simply look for trains, then push or pull and walk through. The door is about three feet high in a standard 36" opening. Clear passageway of 32 inches is maintained for furniture movement. The door will slowly close behind me and I simply need a single finger to pull it tight.

Click on any thumbnail pix for the full size view, about 60k

The door is rugged, two pieces of 3/4" particle board glued and screwed assure no warping. Hung with conventional 3-1/2" hinges with long screws that extend well beyond the door casing and into the stud framing. The stop molding is also rugged and I have a homemade toggle device to insure positive closure. The final closure takes a little more effort against the toggle spring and then it snaps in place. Now we have a good door that can open into the adjoining room or hallway, swinging nearly 180 degrees, it's time to hang the layout framing or benchwork on it.

Support legs The layout framework is screwed to the door with it's front side floating loosely on diagonal braces that reach near the door bottom, thus the frame is free to align itself with the keyways as the door is closed. To maintain accurate track alignment, two keyways are provided. Both consist of a piece of angle iron encountering a hardwood keyway to assure accurate vertical alignment. The facia shows years of stains from hand contact. Funny- never noticed how bad that was 'til the pix was made.

Door keyway

On the swinging end of the door the sliding keyway is lubricated with paraffin wax making it slide easily without risk of staining clothing. A handle is provided for psychological reasons. You can push on the rugged facia (and stain it) to open the door or reach under to pull it closed, but some idiots push and pull on the scenery. The handle says "grasp here". At the bottom of the pix, you can see part of the toggle mechanism. Yeh, it all looks a little battered after more than 25 years, but the tracks are still in alignment and derailments just don't happen! :-)

Toggle device The homemade toggle device is under the benchwork. This pix was taken lying on the floor and looking up. The door is on the left side. Fabricated from a scrap of 1/4" thick aluminum. The stout spring was assembled from a junk box compression spring and scraps of 1/8" iron rod. A roller is loosely screwed into the hardwood keyway piece.

door hinge

At the hinge end, the track on the doorway easily and accurately engages funneled rail joiners on the stationary side of the gap. The rope continues over a pulley some distance away where a hidden bucket of sand is attached to help close the door by gravity action. Much better than a spring device. While it will not snap the toggle, it tends to keep the door closed and the keyways engaged when used casually by family and non RR friends, thus reducing long term stress on the door hinges and framing. A bundle of wires provides power to the tracks and a flashing cross-buck on the other side to warn that a train is approaching. On this side, you can see a train approaching, so no warning device is needed.


On the swinging side of the door, the track is cut at about a 30 degree angle. This is a very important point! (stamp foot, test question!) One wheel flange is always guarded while the other is traversing the gap. You can easily jump a 3/16" gap with zero derailments using this principle and so the gap is no longer critical. In my home, the gap will vary with the seasonal humidity that swells the wood in walls and slightly varies the width of the door opening. The rail ends are soldered to a small flathead screw driven into the roadbed. No spikes for 3 or 4 inches back. With a little heat from your solder iron you can fine tune the track alignment as your door ages. I haven't had to touch this one for many years.

Overhead plot

An overhead plot may help you to better visualize the works.

Electrically, a microswitch senses complete door closure, and in turn closes a three pole relay to apply power to the tracks approaching the door. Needed wiring is routed overhead. A flashing cross buck is on the other side and is activated by the track occupancy system to warn approaching humans. I considered an electric latch that would prohibit opening the door when trains approached but abandoned it for fire or emergency considerations.

That's it- It's stood the test of time- at least 25 years of heavy human and train traffic crossing at grade and no fatalities :-) A couple of freight cars have gone to the floor from backup moves where the engine was beyond the protected limits :-(



The original railroad room was and still is viewed through a non glazed 3 x 8 foot window from the adjoining family that is encircled by the double lap mainline .

Open door For access we opened a dutch door below the window frame and ducked under the framework about 29 inches to the floor. It worked fine when I was young and lithe but eventually it would deny me access. For the first few years we used central control panels because that was the thing to do, so you had to duck under to operate anything. In time we learned the merits of walk-around control and only the Malfunction Junction Yard and the Termite Timber Line Branch had to to be accessed via the duck-under. It was usually a younger operator that volunteered for the job and my old timers just didn't go there anymore.

bridge up We had the duck-under from the family room into the railroad room up until about four years ago, when I went through another back surgery because of my foolish behavior in a non-related avocation. I was locked out of the Teton Short Line for weeks until my son Randy visited and helped me cut out the duck-under and make a hinged lift bridge. This was quite a trick because a yard under catenary AND a curving mainline two inches higher had to be cut.

Catenary The yard and catenary would end on the lift bridge, but the mainline continued over it. The catenary, made from .016" phos-bronze just sort of coils into a spiral and then stretches out nicely again. Ah- it is not a good idea to leave rolling stock on the bridge ;-) We got the job done and Randy went home to his wife and four daughters leaving me with over 200 wires across the two foot gap that had to be rerouted. It was a couple more weeks before I could walk through the opening :-)

hinge ideas

How do you vertically hinge the different levels of track and keep the hinge hardware hidden? My advice is to look at your car door and see how they did it. Look at lots of them, trunk lids too- that's what I did. I can't tell you where to buy such a hinge, you'll just have to use your ingenuity to devise it. Sorry I don't have a pix of the crude hinge, but there is just too much stuff in the way. It wouldn't be much help because your hinging situation will be unique. Get out the paper and pencil, make some cardboard cutouts and use a push pin to locate your hinge point. Like Detroit, you'll figure out how to hide the hinge and have fun doing it.


Like the DOOR, we want easy passageway. It'd be nice to walk up and say "open sesame" but I settled for a one handed operation so the user could keep hold of his coffee cup. As you reach underneath to lift the bridge, there is an obvious handhold, made from PVC pipe. As you start to lift, the handle operates a microswitch to release a magnetic latch and the bridge lifts with little effort. Lift, let go and walk through. A pneumatic door closer (like you use on the screen door), lets it down slowly until it contacts the magnetic latch and locks itself firmly down. The steel plate in the upper left is part of the magnetic lock. When it makes contact with an electromagnet it completes an electric circuit to a relay to reconnect power to the approach tracks.

magnet Horizontal alignment is assured with a tapered steel pin that engages a hole in the 14 gauge steel armature plate described above. The steel plate fully contacts the three pole pieces of the electromagnet providing a tenacious grip that takes a great effort to break. A thicker armature piece would be even better. The electromagnet, salvaged from an old transformer, is powered with 12 Volts DC applied to the old PRIMARY winding (the one that was originally connected to the 120 Volt power line). The secondary windings are of no concern, and can even be failed open or shorted because the DC power essentially ignores them. The electromagnet is powered all the time that the railroad is powered, except for the brief time your hand is on the lift handle. It uses very little power, getting only mildly warm. In most cases you could find a "wall wart" salvaged from some discarded electronic toy to power it.

The electromagnet is assembled from an old transformer similar to something you'd find in a small throttle pack or a Radio Shack transformer in the 20 to 40 va range. The core pieces are disassembled and re-stacked as shown. No fancy tools, A small vise, hammer and a scraper and/or small punch will be all you need. You can even mangle and discard a few of the "E" sections and it won't hurt.

I used a similar system on our HO modular club so the BIG guys can get into the operations area. The problem of maintaining a rigid opening in a module complicates things a bit, but we got it done. Model Railroader has purchased my article about it and hopefully the details will soon be published.

foam scenery

Scenery substrate is a 1/2" sheet of foam rubber, to keep weight down and eliminate impact damage. A little trick I picked up from Lee Nicholas of the UCWRR. It's a natural place to lay something like a piece of rolling stock being passed in or out of the MFJ Yard area with the big five fingered crane. The scenery is not damaged, nor is the something scratched up.

My final summary and advice is:

"Do not build duck-unders into your layout- you WILL regret it"

Seems like I heard that somewhere before. VBG

Winter 2000/01 Well- I finally caved in! The pix above is history. My physical condition had hindered maintenance of the mountainous area on the left and everything was taking on a dirty abandoned look. Spiders, dust and fading was taking over. I called upon the gods and a great earthquake leveled the mountains to the L-girders. A narrow access doorway was cut in and the trackage rerouted with 120 feet of new spline sub-roadbed, Homasote roadbed and MEI code 83 track. We have laid to rest the last of the maintenance duckunders. Nature is at work raising new mountains built of foam that can be lifted out, without ducking, for access to hidden track. Temporarily destroyed, to be rebuilt another day, is the Ross Yard and catenary, and the real water fall.

Spring 2006 Ross Yard and it's catenary was never restored because we found a new source of Mithril and the mine was relocated. The real water fall is better than ever and needs to be written up. View the revised track plan

Return to Teton Short Line Home Page