Actually there was/is quite a bit of dual gauge track in Mt Union as Goosen says. I don't know of any available models of the crane or Chance process coal cleaning plant or any of the brick refactories. I have some drawings of the coal plant that I'm going to use but that won't happen til next year at my current rate of progress. EBT served 3 brick factories in the Mt Union area at various times in the EBT's history. They all had some dual gauge track.
All the track mentioned above is old stuff. I'd suggest making your own track using the new spline formats. The EBT and old PRR tracks make for a pretty big yard by ng standards. I converted my old MR track to the new stitched track but it's only a 2 lod version same as the old MR was.
Following is a Cadrail dwg I made of the track in MT Union. Blue is sg track, orange is ng and the black and red is the dg. IIRC the dg added up to about 8 miles of track total. The common rail was always on the south side - EBT never switched like some ng did which eliminates some awkward transitions.
Zoom in at part of the yard
The track I made has separate components for dg. The mesh for the sg component has the 3 rails and an invisible spline carries the ng. That way making turnouts was easy. The hard part is just laying the track. In TS12 bridge type track that can be used for dual gauge is broken at current time. The patch if they release it may fix that. I think Elvenor's track is based on bridge track. I have made some like that and it's easy to lay but turnouts are a problem and you have to go to 2 separate components to construct them.
Here's a pic of a turnout used with kind bridge type dg track. The bridge track is replaced with separate track components iwo of the junction.
The following pics show parts of the yard in Surveyor. Yellow splines are ng component on the dg track.
Good luck on the MT Union yard. I'd volunteer my track but I think you can do a lot better. While I converted it to stitched track it is pretty poor quality and I'll be making new versions after I retire - which should be soon now.
Bob Pearson
PS Now that I think about it Zec Murphy aka s301 has a tool to space dg track on the dls. I think he worked with 42in gage but may have a 3ft version. (edit: it's broad gauge and sg so no good for EBT but maybe it can be modified I haven't tired it <kuid:103475:38157>). It's broken in TS12 but should work in TS9 - a new feature I guess where spline attachment points closer than 1 m apart don't work anymore on scenery/buildables and the like but that's progress. You might look into it though. 3rd rail for the ng is just a rail and it's laid over the sg track. You may be able to make up something similar although kind bridge track can be used as track gauge for laying dg with separate components - just slow going.
PPS Someone made a set of 3' ng stub turnouts, Pencil42 maybe, I'll have to check (edit: no his are sg but I thought someone made 3ft versions based on his but can't find anything). Elvenor did make some 3' ng stub turnouts but I don't know if they still work. Trouble with mixing and matching track and turnouts is the ballast never matches. Many of EBT turnouts in the yards were left as stub and they had a few 3 ways. I think all the mainline turnouts were replaced with point type in the early 1900's. Elvenor made some wigwag (harp frame) type levers based on D&RG and DSP&P. The EBT used a slightly different version of them but I don't think they were used in the Mt Union yard at least in later years - I don't recall any pics of them. Rockhill Furnace yard and shops retained a few though - also in Robertsdale area. I prefer his low height switchstands but they don't fit too well with the EBT track spacing in the yards. They don't match up well with the various types the EBT used over the years either.