3 rail dual gauge

[xcalibur201]

Hello, people of trainz! I'm a guest in your community, I hope you don't mind my presence. I come to you with a question. For some reason, I'm interested in rail gauge, and have read into this a fair amount. When it comes to dual gauge, you can make a three rail arrangement with gauges that are far enough apart (eg cape gauge & standard), while for those close together, you need four rails (eg standard & russian). But I'm wondering, what is the limit? How different do rail gauges have to be to allow for a three-rail setup? It seems to be ~6 inches or so, but I'm not certain; also, is this limit different for broad vs narrow gauges? This information is surprisingly difficult to find, which is why I turn to the enthusiasts here.

(tl;dr: how far apart do rail gauges have to be to allow three-rail dual gauge?)

TIA

 

[flyboy559]

There really isn't a simple answer to your question. For starters, with a 4 rail system, you can put railcars of either gauge on the same train without using special idler cars as long as the couplers and brake systems match properly.

Per wikipedia "Tracks of multiple gauges involve considerable costs in construction (including signalling work) and complexities in track maintenance, and may require some speed restrictions. They are therefore built only when absolutely necessary. If the difference between the two gauges is large enough – for example between 1,435 mm (4 ft 8+1⁄2 in) standard gauge and 3 ft 6 in (1,067 mm) – three-rail dual-gauge is possible, but if not – for example between 3 ft 6 in (1,067 mm) and 1,000 mm (3 ft 3+3⁄8 in) metre gauge – four rails must be used."

 

[xcalibur201]

There really isn't a simple answer to your question. For starters, with a 4 rail system, you can put railcars of either gauge on the same train without using special idler cars as long as the couplers and brake systems match properly.

Per wikipedia "Tracks of multiple gauges involve considerable costs in construction (including signalling work) and complexities in track maintenance, and may require some speed restrictions. They are therefore built only when absolutely necessary. If the difference between the two gauges is large enough – for example between 1,435 mm (4 ft 8+1⁄2 in) standard gauge and 3 ft 6 in (1,067 mm) – three-rail dual-gauge is possible, but if not – for example between 3 ft 6 in (1,067 mm) and 1,000 mm (3 ft 3+3⁄8 in) metre gauge – four rails must be used."

I get that, but as you see in that quote from the notoriously unreliable Wikipedia, it says "If the difference between the two gauges is large enough". I'm asking what that figure is. WP also says that you can combine 3' & 3'6", but not 5' & 5'6", even though the difference seems very similar (that's why I asked if narrow vs broad is different).

Again, I'm only making this request because I searched far and wide, but turned up nothing. You'd think this would be basic info, which gauges work for 3 rails...

 

[pware]

I can refer you to an article I wrote on this several years ago. The article is at https://worldwiderails.com/break-of-guage-rail-gauges/

 

[pitkin]

I can refer you to an article I wrote on this several years ago. The article is at https://worldwiderails.com/break-of-guage-rail-gauges/

I really enjoyed your article, with pictures.

 

[clam1952]

I can refer you to an article I wrote on this several years ago. The article is at https://worldwiderails.com/break-of-guage-rail-gauges/

Good article well written.
As an aside the Penrhyn Quarry line is no more the preservation project failed, mismanagement and a falling out with the owners of the site.

 

[xcalibur201]

Can confirm, it's a quality article, but it doesn't give me the definitive answer I'm looking for. It mentions that you can make 3-rail dual gauge with Standard & Irish, which I believe is a difference of 6 1/2". So is that it? 6.5 minimum for broad gauge, and 6 for narrow gauge? And why would there be that minor difference of .5?

Obviously if there's 1 foot of difference, it'll be fine. And if there's only 3" between, it's too small. I'm trying to narrow this down.

Again, don't mind me, I'm just trying to get to the bottom of this.

 

[flyboy559]

The thickness of the flanges on your rolling stock is going to be the ultimate factor. There needs to be room in there for the flanges, plus a little extra for safety. Given the size of the flanges and flangeways where I work, I would say 4" would be the minimum gap for using a 3 rail system.

 

[bnsfc]

There is also the question of frogs. Assuming you want a switch I would imagine there is a minimum distance where a frog has the room to be used, otherwise they cant really help guide the wheels. Ties into the flange thickness and how much wiggle room you want there.

 

[xcalibur201]

The last two posts are what I was looking for -- but I've received an answer elsewhere which I think finally resolves this issue. The minimum seems to be 6.5 in. That's about the difference between Standard & Irish gauge, which is a tight fit. The stuff I read suggesting 6" must've been wrong. Thanks anyway for participating! I guess that resolves my question, unless you want to clarify/discuss further.

 

[jordon412]

I've got a question regarding dual gauge railroads, specifically where Russian Gauge meets Standard Gauge. If there is to be a bridge or tunnel over or under the Bearing Strait for all the goods produced in Asia, it would have to move via rail thru China, Russia, Alaska, Canada, and finally the lower 48. All these nations use Standard Gauge, which is 1,435 millimeters, or 4 feet, 8 1/2 inches, except Russia, which use Russian Gauge, which is 1,520 millimeters, or 4 feet, 11 27/32 inches. Are the gauges too close to each other for them to have 3-rail dual gauge trackage?

 

[xcalibur201]

I've got a question regarding dual gauge railroads, specifically where Russian Gauge meets Standard Gauge. If there is to be a bridge or tunnel over or under the Bearing Strait for all the goods produced in Asia, it would have to move via rail thru China, Russia, Alaska, Canada, and finally the lower 48. All these nations use Standard Gauge, which is 1,435 millimeters, or 4 feet, 8 1/2 inches, except Russia, which use Russian Gauge, which is 1,520 millimeters, or 4 feet, 11 27/32 inches. Are the gauges too close to each other for them to have 3-rail dual gauge trackage?

Standard and Russian are definitely too close for 3-rail dual gauge, since the difference is only 3.5 in. As I said above, it seems that the minimum is 6.5 in (unless anyone here objects).

 

[pware]

The image shows long distance dual gauge track in Lithuania without a shared rail. The first and third rails (from the left) are standard gauge. The second and forth rails are Russian broad gauge (1520mm). The two gauges differ by only 85mm, too close to share a common rail.

The distance you are proposing would probably make laying 4 parallel rails for one track (8 rails for 2 tracks) uneconomic. You are essentially doubling your construction and maintenance costs (including signalling and switching). It would be cheaper to select a single gauge and use that even if it means adding break of gauge infrastructure at one end of the hypothetical Bering Strait tunnel.

My thoughts.

 

[jordon412]

The image shows long distance dual gauge track in Lithuania without a shared rail. The first and third rails (from the left) are standard gauge. The second and forth rails are Russian broad gauge (1520mm). The two gauges differ by only 85mm, too close to share a common rail.

The distance you are proposing would probably make laying 4 parallel rails for one track (8 rails for 2 tracks) uneconomic. You are essentially doubling your construction and maintenance costs (including signalling and switching). It would be cheaper to select a single gauge and use that even if it means adding break of gauge infrastructure at one end of the hypothetical Bering Strait tunnel.

My thoughts.

The dual gauge section would only stretch from the China-Russia border across the Bering Strait. However, this is only hypothetical as the current relations between Russia and the U.S. would prevent this railroad from happening. However, another option is to have two tracks on the main line, one Russian Gauge, one Standard Gauge, with passing sidings along both tracks, between the China-Russia border and the Bering Strait.