Grand Union

[velotrain]

Grand Union under construction in Montreal, 1893

 

 

 

 

[brill27mcb]

Grand Union under construction in Montreal, 1893

 

 

Wow, it is not even symmetric (side to side)! (Look at how the outer curve rails relate to the 90-degree crossing frogs.)

 

Rich K.

[velotrain]

I noticed that also Rich.  All I can think of is that it was in fact built 122 years ago, without our modern conveniences.

 

Do you know how rail was bent back then? 

 

I've seen several photos of paved grand unions, but it's somehow more impressive in the raw.

[ozman2009]

What a job it would be to make a model of it! A Z scale version would definitely be a bridge too far.

[velotrain]

What a job it would be to make a model of it! A Z scale version would definitely be a bridge too far.

 

I suspect the actual trackwork might pale compared to the turnout control and wiring - above and below  ;-)

 

I suspect Rich has seen models of this, perhaps more likely in O scale than HO - and certainly nothing smaller!

 

Are working trams even produced in Z scale?

 

 

Well, it looks like I was wrong - on at least one count.

 

https://www.youtube.com/watch?v=AndtnhjvnSA

[velotrain]

More grand unions - from the site of the guy who made the above video.

 

http://dan-d-sparks.blogspot.com/2013/12/not-first-grand-union-intersection.html

 

The German video has a lot of tram action.

[velotrain]

It turns out there are still three functioning grand unions in Toronto.

 

 

 

 

Some guy named Walter really likes building complex trackwork.  Here is his model of a 5-way grand union in Toronto, at the intersection of King and Queen streets, and Roncesvalles Ave.  I tried looking at satellite view to see if it is still there, but the image quality is too poor.  However, there is a very large LRV yard there.

 

 

 

 

Walter also made a model of a 6-way junction in Chicago, although not all lines connect with each other.

 

 

 

 

I found a very grainy image of the prototype being constructed.  I can't tell if they actually built it while the streetcars were running - or, much more likely, this is a posed publicity shot.

 

 

[kvp]

 

I suspect the actual trackwork might pale compared to the turnout control and wiring - above and below ;-)

If you use springs for half the turnouts, then you only need 2 switches for each direction (straight-right, straight-left), meaning only 8 in total for a double track to double track grand union. For electricity, you can use power everywhere turnouts and put isolators into the middle of the curved sections (or ovearhead if you use a live one). This means each track can have its own controller (a total of 4) and trams running on the curves are handed over from one controller to the other. This makes wiring and routing really easy. The best part is that power feeds can be placed away from the grand union and each direction on each line has a dedicated controller. Polarities will always match if running directions are consistent on both lines. This also scales up to larger grand unions.

[Mudkip Orange]

I noticed that also Rich.  All I can think of is that it was in fact built 122 years ago, without our modern conveniences.

 

That's intentional.

 

If you build a perfectly symmetrical grand union, you end up with three-directional frogs. There is a single point in space where flanges operating in three directions occupy it in the course of normal operation. This is... sub-optimal. You want to break it apart into multiple standard frogs. It also helps if you can offset your switch points even just a little bit.

[marknewton]

Do you know how rail was bent back then? 

 

They would have used a tool like this - a gadget with the unfortunate name of "Jim Crow":

 

 

Similar tools are still used today, either manual or hydraulic powered.

 

All the best,

 

Mark.