What about multiple gauges?

[Wayne Laepple]

Here's a photo taken by Robert Wilson in Gladstone, South Australia, in 1969, when the five-foot gauge and 3-foot six-inch gauge lines were being converted to standard gauge. How would like to be the guy whose job it was to keep that turnout properly adjusted?

[John Kokas]

Same was done on the D&RGW dual gauge lines for years.  In fact there is still a little dual-gauge track in and around Antonito, Co.

[James Patten]

There's quite a bit of dual gauge in Australia, as each individual state (province?) decided their own gauge way back when, but in recent decades the federal government required a standard gauge link between all of them.  I think the only 3'6" gauge left in South Australia is in preservation. 

[Philip Marshall]

I'm pretty sure the only dual gauge left in Antonito is a short piece of display track (including a turnout) in front of the C&TS depot, plus a few rail lengths on either side of the grade crossing with the famous "End of Standard Gauge" sign. Other than that it's all gone now, and the narrow gauge and standard gauge are no longer physically connected at Antonito.

There is still a bit of dual gauge on the EBT in Mount Union though, for now at least.

[Wayne Laepple]

I recently saw a photo of a Penn Central diesel moving a boxcar through the Mount Union yard taken about 1970. I knew the firebrick plant was still in operation, and I had seen cars there waiting to be loaded, but this photo is the first proof of how the cars got there. I have often wondered what the arrangement was with the EBT for the big railroad to do that. I also saw the EBT trackmen putting ties in the track, but only spiking the standard gauge rails.

[Dag Bonnedal]

Here is another example, that here in Sweden was referred to as "world unique" (which is wasn't).
It was in the town of Växjö in southern Sweden where the 42" gauge network to the south met the 35" (891 mm, 3 old Swedish ft) gauge network to the north and also the std. gauge network. It was in use into the 1970-ties.

https://digitaltmuseum.se/021018138395/vaxjo-bangard-tre-sparvidder

And, by the way, you can not only stack the gauges horizontally, you can do it vertically as well:
http://i210.photobucket.com/albums/bb41/railwaypictures/forumbilder/2014/10288801_1401652300115648_4267433297246971952_n_zps92b63f99.jpg~original

This is a 35" coach going for a rebuild in a workshop on the 42" network. Thus first transported on a special std. gauge car for transporting ng. stock. Then this contraption loaded on two 42" transporters. Simple enough.

[Gary Kraske]

While visiting the operating tourist EBT, their history involved engineering co-operation with the Pennsylvania RR such that at Mt. Union a crane system was constructed to move standard gauge coal car bodies, unloaded or loaded, but not trucks, up- over and onto EBT 3' gauge trucks.  Of course this was approved and blessed by the Pennsy.

[ALAIN DELASSUS]

In France the most popular tourist RR, le Chemin de Fer de la Baie de Somme  www.cfbs .eu , a three-footer, has a long strech of its main line  built with a three rail track  that can accomodate standard gauge rolling stock. When a Steam Festival is held standard-gauge steam locomotives come not only from France but from UK and Germany as well. The two-gauge line was built to allow standard-gauge freigt cars to reach Saint Valéry as of Noyelles SNCF station. Those freight cars were hauled by three-foot gauge locomotives  by the means of a special flatcar fit with both standard and two-foot gauge draft gears.