Normal tram tracks and Translohr tram tracks crossing over each other.

[busestrains]

So in Paris new tram line T10 (a normal tram line) which is currently under construction will cross over line T6 (a Translohr tram line) so i am a bit confused how this will work. I have been trying to wrap my head around this. It does not seem possible for a Translohr track to cross over a normal track.

Surely for the Translohr track to work you would have to have such a large gap in the crossover that it would derail the normal tram? Or likewise for the normal track to work you would have to have such a large gap that it would derail the Translohr tram?

So my question is how is this actually going to work? Is there a way for a Translohr track and a normal track to successfully cross over each other and allow the trains to safely cross over the lines without derailing?

Also i am not sure if this thread is better placed in the tram section or the international section of the forum as it is about both but i have put it in the international section. But feel free to move the thread if it would be better in the tram section.

 

[STEVIEBOY1]

I just looked up what Translohr is, it does seem a bit odd?

 

[stuu]

So in Paris new tram line T10 (a normal tram line) which is currently under construction will cross over line T6 (a Translohr tram line) so i am a bit confused how this will work. I have been trying to wrap my head around this. It does not seem possible for a Translohr track to cross over a normal track.

Surely for the Translohr track to work you would have to have such a large gap in the crossover that it would derail the normal tram? Or likewise for the normal track to work you would have to have such a large gap that it would derail the Translohr tram?

So my question is how is this actually going to work? Is there a way for a Translohr track and a normal track to successfully cross over each other and allow the trains to safely cross over the lines without derailing?

Also i am not sure if this thread is better placed in the tram section or the international section of the forum as it is about both but i have put it in the international section. But feel free to move the thread if it would be better in the tram section.

It goes under a bridge, so there is no physical connection. Which is just as well as it does seem a tricky problem. I suppose you could have some sort of thing that moves up and down, but that sounds like no end of trouble

 

[30907]

There are tram crossings of normal rail lines (eg Haberstadt in Germany) which work OK - how big is the difference between a conventional rail flange gap and the Lohr system?
Academic question anyway in the light of stuu's post.

 

[busestrains]

I just looked up what Translohr is, it does seem a bit odd?

Yes it is certainly a very odd system. There is only a few of them in use around the world. I guess it is cheaper than building a normal tram line.

It goes under a bridge, so there is no physical connection. Which is just as well as it does seem a tricky problem. I suppose you could have some sort of thing that moves up and down, but that sounds like no end of trouble

Many thanks for that. That answers my question then. That makes sense that it is going under a bridge. It would be quite difficult otherwise. I am sure that some sort of complicating thing could be built to allow them to cross each other but as you say that would just be trouble and more problems and complexity so a bridge certainly sounds like a better option.

There are tram crossings of normal rail lines (eg Haberstadt in Germany) which work OK - how big is the difference between a conventional rail flange gap and the Lohr system?
Academic question anyway in the light of stuu's post.

Yes tram crossings of normal railway lines work fine. As well as in Germany these also exist in Australia and Estonia and probably a few other places. But these are just two normal tracks crossing each other so it is very simple. With the Translohr trams i believe the two rails that connects the tram to the guide rail go down at a diagonal angle so you would need a much bigger gap if it crossed normal rails. I am not too sure though. There might be a way to make it work.

 

[popeter45]

Yes it is certainly a very odd system. There is only a few of them in use around the world. I guess it is cheaper than building a normal tram line.

no they are actually more expensive as the rail is not a standard type
in reality its a gadgetbahn that was built to generate french jobs

 

[stuu]

There are tram crossings of normal rail lines (eg Haberstadt in Germany) which work OK - how big is the difference between a conventional rail flange gap and the Lohr system?
Academic question anyway in the light of stuu's post.

If you look on the Wikipedia page, it has a diagram showing how the rail/guide wheels work. There would need to be a significant gap in both rails.

It's a bit baffling the French persisted with Translohr while simultaneously building normal trams nearby.

 

[AdamWW]

no they are actually more expensive as the rail is not a standard type
in reality its a gadgetbahn that was built to generate french jobs

Quite good for making sure that when rolling stock renewal time comes round there's only one place to go to get the new trams, I would have thought.

 

[edwin_m]

You might be able to do it by crossing at an angle, say 30 degrees, so that when the tram wheel on one side was passing over the two largeish Translohr flange gaps, the other wheel was in a normal grooved rail which would steer the tram and avoid derailment. However I don't know if the Translohr flange gap is shallow enough to allow the tram to cross it using flange tip running.

I think the Translohr has a tighter turning radius than most trams - the one below is well under 20m. But on trying out this route a few years ago, it was much more cramped than a tram with a lot of space taken up by the housings for the rubber wheels.

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[Roast Veg]

I think the Translohr has a tighter turning radius than most trams - the one below is well under 20m. But on trying out this route a few years ago, it was much more cramped than a tram with a lot of space taken up by the housings for the rubber wheels.

Translohr is never the right choice for anything, truly the worst of all worlds. There are plenty of examples of conventional trams with tighter radii, New Orleans for example managed it with a track gauge bigger than standard.

 

[AlbertBeale]

There are tram crossings of normal rail lines (eg Haberstadt in Germany) which work OK - how big is the difference between a conventional rail flange gap and the Lohr system?
Academic question anyway in the light of stuu's post.

The bigger problem than different track systems can be different power supply systems interacting - eg some continental cities that have tram and trolleybus services criss-crossing the same junctions. Given that both the electrical and mechanical aspects of the two sort of overhead wires are very different, it's astounding to see how they manage it. (I once nearly got run down at an intersection in Linz whilst standing in the road looking up and marvelling at the rather subtle complexity of the wiring above my head.)

 

[AdamWW]

The bigger problem than different track systems can be different power supply systems interacting - eg some continental cities that have tram and trolleybus services criss-crossing the same junctions. Given that both the electrical and mechanical aspects of the two sort of overhead wires are very different, it's astounding to see how they manage it. (I once nearly got run down at an intersection in Linz whilst standing in the road looking up and marvelling at the rather subtle complexity of the wiring above my head.)

Yes Linz is quite impressive, isn't it?

There's also some less complex but interesting wiring where trolleybus wires cross with "tram" (more light rail really) lines in St Gallen in Switzerland.

The normal 1.5 kV drops to 600 V for the road running section though.

*St Gallen also has the novelty of double articulated bendy-buses - somehow having the trolley on the rear segment works - but no longer trolleybuses pulling trailers).

 

[Taunton]

If you look on the Wikipedia page, it has a diagram showing how the rail/guide wheels work. There would need to be a significant gap in both rails.

It's a bit baffling the French persisted with Translohr while simultaneously building normal trams nearby.

It is a French characteristic to not only come up with such systems but run them long term, unlike other bizarre technologies which come and quickly go. The Pneu trains of the Paris Metro etc are another. They successfully managed to get those compatible with conventional rail as well. Elsewhere you have cablecars (San Francisco and a few other places), where the tracks cross over one another in the street quite successfully. Not for nothing do "engineer" and "ingenious" come from the same root.

I think the Translohr has a tighter turning radius than most trams - the one below is well under 20m. But on trying out this route a few years ago, it was much more cramped than a tram with a lot of space taken up by the housings for the rubber wheels.

I think that on a multi-articulated vehicle, like modern trams, the body connections are more of a constraint on curve radii than any wheels on the track. I do notice that such trams nowadays seem unable to take curves, and indeed points, at more than walking pace. How fast does the Translohr go round corners?

 

[AdamWW]

It is a French characteristic to not only come up with such systems but run them long term, unlike other bizarre technologies which come and quickly go. The Pneu trains of the Paris Metro etc are another. They successfully managed to get those compatible with conventional rail as well. Elsewhere you have cablecars (San Francisco and a few other places), where the tracks cross over one another in the street quite successfully. Not for nothing do "engineer" and "ingenious" come from the same root.


I think that on a multi-articulated vehicle, like modern trams, the body connections are more of a constraint on curve radii than any wheels on the track. I do notice that such trams nowadays seem unable to take curves, and indeed points, at more than walking pace. How fast does the Translohr go round corners?

The Translohr web site claims the advantages to be a narrow "clearance gauge" of 5.18 m (not sure what they mean by that), "improved" braking performance, 10.5 m turning radius, ability to run up slopes of 13% and silent running.

I wouldn't mind going on one just for the experience.

 

[edwin_m]

The Translohr web site claims the advantages to be a narrow "clearance gauge" of 5.18 m (not sure what they mean by that), "improved" braking performance, 10.5 m turning radius, ability to run up slopes of 13% and silent running.

I wouldn't mind going on one just for the experience.

The clearance gauge looks like the width of the envelope for double track, which depends only on the vehicle width and the requried clearance between vehicles or between them and an obstruction. Trams can also be down to a similar width, which makes them more cramped inside but probably not as cramped as the Translohr, due to the wheel housings I mentioned above.

Improved braking and silent running comes from the fact the weight of the vehicle is on rubber tyres, with the steel wheels used only for guidance. This also makes them less energy-efficient than trams (if I recall correctly the similar but now obsolete Bombardier GLT used about 50% more than a comparable tram), and they will generate tyre particulates.

 

[AdamWW]

Improved braking and silent running comes from the fact the weight of the vehicle is on rubber tyres, with the steel wheels used only for guidance. This also makes them less energy-efficient than trams (if I recall correctly the similar but now obsolete Bombardier GLT used about 50% more than a comparable tram), and they will generate tyre particulates.

And wear out the road because the tyres always take the same path. It's bad enough in some places just with bus lanes.

But you wouldn't expect the web site to point out the deficiencies, would you?

And after all according to the web site there are zero C02 emissions so why worry about the efficiency? (Just don't ask where the electricity it uses comes from...)

 

[edwin_m]

And wear out the road because the tyres always take the same path. It's bad enough in some places just with bus lanes.

The Translohr route I rode on in Paris had concrete in the area the tyres passed over, probably for this very reason. Having to provide this also introduces some of the problems of a street tramway, such as the need to re-locate utilities that are physically in the way or which may require access after opening. The slab may however be shallower than a tramway, as the load is imposed on it at the road surface not at bottom of rail.

 

[DanielB]

Yes Linz is quite impressive, isn't it?

There's also some less complex but interesting wiring where trolleybus wires cross with "tram" (more light rail really) lines in St Gallen in Switzerland.

The normal 1.5 kV drops to 600 V for the road running section though.

*St Gallen also has the novelty of double articulated bendy-buses - somehow having the trolley on the rear segment works - but no longer trolleybuses pulling trailers).

The same in Bern by the way. Both are interesting as the wires not only cross, but also run parallel on lengthy sections of route. Even in relatively narrow streets in the city centre in Bern.

 

[30907]

If you look on the Wikipedia page, it has a diagram showing how the rail/guide wheels work. There would need to be a significant gap in both rails.

Yes, but no dimensions, hence my comment - however, the "double-dip" gap for the conventional tram would be a problem, and I had overlooked that. Good thing there's a bridge!

 

[AdamWW]

Yes, but no dimensions, hence my comment - however, the "double-dip" gap for the conventional tram would be a problem, and I had overlooked that. Good thing there's a bridge!

It would be quite fun to see a cross-over. No doubt it could be done at an unreasonable expense (e.g. a platform with the appropriate rails on opposite sides which flips over as appropriate, as with some monorail points).

 

[edwin_m]

It would be quite fun to see a cross-over. No doubt it could be done at an unreasonable expense (e.g. a platform with the appropriate rails on opposite sides which flips over as appropriate, as with some monorail points).

Or a turntable with the Translohr rail running parallel with the tram rails on their centreline, rotating to align for whichever vehicle is approaching.

 

[stuu]

Yes, but no dimensions, hence my comment - however, the "double-dip" gap for the conventional tram would be a problem, and I had overlooked that. Good thing there's a bridge!

This is what the wheel unit and guidance section looks like. Looking at photos elsewhere I would guess the wheelbase at about 1.5m, and the guidance wheels look at least 150mm, I would have thought it would mean a gap of something like 100mm would be needed in a tram rail to cross through

 

[AdamWW]

Or a turntable with the Translohr rail running parallel with the tram rails on their centreline, rotating to align for whichever vehicle is approaching.

Didn't think of that. Yes the two schemes should be perfectly capable of "mixed gauge" operation - but splitting/joining the routes would be tricky. You could imagine an application where they met end on with an overlapping section. Though why you'd do that I've no idea.

 

[D6130]

Didn't Caen build a Translohr system a few years ago, which had to be replaced - prematurely and very expensively - due to chronic unreliability!

 

[edwin_m]

Didn't Caen build a Translohr system a few years ago, which had to be replaced - prematurely and very expensively - due to chronic unreliability!

That was the Bombardier TVR I referred to above.

 

[MarcVD]

In a nutshell : translohr was about to get bankrupt, so the French government asked Alstom to take it over. In exchange Alstom requested the French government to guarantee them a steady flow of revenue. Said French government then twisted RATP's arm to equip some of the foreseen tram lines with translohr technology. The technical justifications for this "choice" are all made up. The only real reason was to save jobs.

 

[edwin_m]

In a nutshell : translohr was about to get bankrupt, so the French government asked Alstom to take it over. In exchange Alstom requested the French government to guarantee them a steady flow of revenue. Said French government then twisted RATP's arm to equip some of the foreseen tram lines with translohr technology. The technical justifications for this "choice" are all made up. The only real reason was to save jobs.

Jobs that would have almost certainly otherwise gone to other Alstom employees, considering that Citadis is pretty universal on French tramways.

 

[Gostav]

Just like my question about the "new rail transit system" in the diverse Tokyo area many years ago, does a city really need all kinds of completely different rail transit systems?

There are two Translohr tramways in China (Tianjin and Shanghai) and what l hear is the systems only have few advantages, all extension plans were cancelled due to the Translohr system unreliable and expensive. Tianjin's Translohr tramway is on the verge of closing.

 

[AlbertBeale]

The same in Bern by the way. Both are interesting as the wires not only cross, but also run parallel on lengthy sections of route. Even in relatively narrow streets in the city centre in Bern.

And I seem to remember that Zurich also has an interlacing set of trams and trolleybuses with wonderful overhead knitting at complex junctions.

 

[DanielB]

I've recently seen a video from Zürich regarding complex intersections indeed: they've buit a huge installation to allow a trolleybus to cross the Utlibergbahn which is converted to 15 kV.