Timesaver Switching Puzzle


This page gives some history, about:

  • the classic switching puzzle itself
  • a project to construction of a small, light portable configuration
  • SDGRS presenting a larger version for the annual Boy Scouts meeting in San Diego.

History / what is the Timesaver?

This page is about the classic switching puzzle invented by John Allen, the famous model railroad pioneer.

The trackplan is simple, but has been enjoyed by many people since it's introduction by John in 1972. The lengths of track and arrangement of switches have been designed to make you have to think about how you move the cars.


We are presenting the most authentic design and rules as were put forwards by John himself, honoring John, and also as a correct representation for assisting Boy Scouts in achieving a merit badge in railroading.


This is from the article in Model Railroader in 1976:

MR1976 cropped2


timesaver schematic

Again, the numbers show the capacities of cars on that section of track.


In the pictures below, the locomotive is the orange box starting in the "middle".

The goal is to put the cars in the starting order below, and then use the least moves and time to get to the "ending" locations"


 Starting locations:  Ending locations:


Here is an excellent article explaining the history: http://www.wymann.info/ShuntingPuzzles/sw-timesaver.html

Here's a link to the original rules for the puzzle: http://www.wymann.info/ShuntingPuzzles/Timesaver/timesaver-rules.html


Portable construction:

Goals are:

  • small enough to fit in back seat or trunk of any car
  • light
  • easy to set up


Folding table:


Under development is a minimal portable design. We found a lightweight folding table, 2 foot by 8 foot, that weighs only 20 pounds as opposed to the 55 pounds you get from Costco.

I've worked on the track plan using LGB track, to follow the lengths of the sidings as to the original design: (the separate track is an option to hold more cars.

Timesaver 3

This implementation uses:

  • 3 pieces LGB 12150 left hand switch
  • 2 piece LGB 12050 right hand switch
  • 1 piece LGB 11000 curved track
  • 8 pieces LGB 10000 straight (12") track
  • 5 pieces LBG 10150 straight (6") track


The grid is 1 foot squares, so you can see that this layout is about 1-1/2 foot by 8 foot.

A small power supply will be installed with reduced voltage for slow speed, and a left-off-right toggle switch for speed and direction to make it simple. The original HO version was set so the loco traveled 3 feet in 15 seconds.

Kadees will be mounted for automatic remote uncoupling with magnets placed at appropriate locations

So I started laying out track, to find a way to use stock LGB sizes and follow the "siding lengths" that make the puzzle work.

Here's an initial mockup:

timesaver mockup 1


Below I was trying to match some of the "simplified" renditions of the puzzle, again tweaked to work around the lack of a WYE switch:

timesaver mockup 2


Below is the final design, with the siding lengths correct. The goal was also to make gaps align with the center 2 sections The goal is to permanently fix the track in the center 2 sections (which fold to the outside of the table) and have rail clamps to connect when assembled.

timesaver mockup complete


"Folding" the track:

To meet the minimal setup criteria, it makes sense to fix as much track in place as possible. When the table folds, it the center 2 sections (2 and 3) are exposed on the outside, so I have focused on how to do this.

Clearly the track needs to come apart at the joints, so as mentioned earlier, I worked with the design to make as many of the track joints exactly align with the table sections.

Below is a picture of the joint between sections 1 and 2 (numbered from the left). The 2 tracks to the left of the joint will be slipped on after opening, and the joints line up perfectly with the track.

joint 1 2


Below is a picture of the joint between sections 2 & 3. Again things line up perfectly. The top track ends, but optionally another track could be slid on. The bottom 2 tracks will have removable rail clamps, probably a different design that is easier to put on and off.

joint 2 3


The picture below shows the last joint set, between sections 3 & 4, and the top track can use clamps, but the bottom switch needs to be removed for transport, thus the clamps on the switch itself:


joint 3 4


Boy Scouts

We normally put together a large version of this design for the annual boy Scout meeting in San Diego. Boy Scouts can get a merit badge for executing the puzzle. For this event, our representation uses all LGB track, and R3 switches. We use 5 "G scale" 1:29 freight cars, and one loco, all of these are approximately equal length.

This version uses gentler curves and switches allowing full length US freight cars and larger locos.


 boy scout