[MOC] Dublin Luas - Alstom Citadis tram

[Duq]

It's finally finished!

Luas full length

Luas is the tram here in Dublin, and I've been wanting to build one for a long time. I started about a year ago, when I got the general concept for the cars figured out, but then abandoned it for a while. Sometimes the inspiration just isn't there...
Anyway, over the past few weeks I figured out the cabin, the connections between the sections, improved the doors, which required a different way of doing the roof.... One thing I decided right at the start is that I wanted to do the micro-stripe yellow above the purple. The first idea was to use brackets (1x2/2x2 and 1x2/2x4) and you can still see those in the middle section.

Luas middle section

However for the outer sections I had to change the concept, as the plate part of the brackets got in the way of the sideways built doors. I ended up using flags, but getting enough of them in yellow and in the old mold (the clip is slightly different in the newer ones, and unfortunately Bricklink doesn't differentiate) was not easy.

It's powered by a 9V train motor in the middle and it can manage the tight curves:

Luas inside curve

It does have a bit of an overhang, so don't park close to the tracks ;-)

Figuring out the shape of the 'dressed up' bogies was not easy, despite the simplicity of the final design. Getting the bodie shape around them was even harder.

The connectors between sections were another headache that's gone through umpteen different designs. In reality they're an accordion-type structure which is impossible in Lego. So I needed something that would keep the sections close on the straights, and would allow the tram to go around standard curves without showing a big ugly gap. For transport it also had to be easy to take the sections apart and for reliable running the connection has to have some flex when the track isn't perfectly level. I managed to do all of that:

 

[Andy Glascott]

Very impressive @Duq, instantly recognizable and you’ve done a good job on the cab too with the different angles involved. 

[UltraViolet]

  So, this is the original Citadis 301 30-meter model, correct?  Certainly far less 'unwieldly' than the latest 402/502 models at a whopping 55-meters long with nine body sections!

  I really appreciate the effort you've gone to including all the proper detail of the roof-mounted equipment and the articulations, while keeping exposed studs to a minimum.  That is what steps it up to the level of looking more like a genuine model than a LEGO build.  Is your build 7-wide?  Would you be able to post a full-length photo of the roof detail in an overhead view?

  You're really temping me to build a Citidis of my own now, but I must restrain myself until I get my Bombardier Flexity Outlook fully finished (a somewhat less-wieldly 30m vehicle with five body sections).  You've used a very similar technique to mine on your pantograph, BTW.

[idlemarvel]

Wonderful model. If that's just 7wide you've worked miracles, if it's only 6 wide you're a magician! I love the way you've hidden the wheels. Are there just the two bogies for the whole unit? Great work.

[Feuer Zug]

Great work on the Dublin tram. I can see how the segment connectors would be a right pain. They look marvelous.

[Duq]

16 hours ago, UltraViolet said:

  So, this is the original Citadis 301 30-meter model, correct?  Certainly far less 'unwieldly' than the latest 402/502 models at a whopping 55-meters long with nine body sections!

  I really appreciate the effort you've gone to including all the proper detail of the roof-mounted equipment and the articulations, while keeping exposed studs to a minimum.  That is what steps it up to the level of looking more like a genuine model than a LEGO build.  Is your build 7-wide?  Would you be able to post a full-length photo of the roof detail in an overhead view?

  You're really temping me to build a Citidis of my own now, but I must restrain myself until I get my Bombardier Flexity Outlook fully finished (a somewhat less-wieldly 30m vehicle with five body sections).  You've used a very similar technique to mine on your pantograph, BTW.

Thanks! Yes, forgot to mention, it's 7 wide. Thank you designers in Billund for the 1x5 plate...

This is the original 30 meter 301. They have all been upgraded to 5 sections due to demand and then later orders were indeed the 7 and 9 sections up to 55 meter long. I wonder if that's actually good for capacity, or whether more shorter trams would be better. Wonder how difficult the longer versions would be, with 'floating' sections. How do you keep the connection flexible for uneven track but rigid enough to keep the floating section upright?

I will add more photos. I took one of the roof but it didn't come out quite right. The equipment is reasonably accurate, but you're very limited in what you can do with only 3 plates height.

8 hours ago, idlemarvel said:

Wonderful model. If that's just 7wide you've worked miracles, if it's only 6 wide you're a magician! I love the way you've hidden the wheels. Are there just the two bogies for the whole unit? Great work.

Thank you! As mentioned above, yes, it's 7 wide. I don't know about miracles, but there certainly was a lot of trial and error. ;-)

The bogies with body plating are very distinctive, and only the older series have them. The bogies use the tiny train wheels to fit below the windows. There are 2 bogies as you can see, but the middle section also has wheels inside its body plating - that's where the train motor is hidden.

 

19 hours ago, Andy Glascott said:

Very impressive @Duq, instantly recognizable and you’ve done a good job on the cab too with the different angles involved. 

Thanks Andy!

4 hours ago, Feuer Zug said:

Great work on the Dublin tram. I can see how the segment connectors would be a right pain. They look marvelous.

Thank! I might reveal the secrets in the next photo session ;-)

[zephyr1934]

The build looks fantastic, you've made some tricky angles look easy

 

On 10/1/2023 at 6:23 PM, Duq said:

The connectors between sections were another headache that's gone through umpteen different designs. In reality they're an accordion-type structure which is impossible in Lego. So I needed something that would keep the sections close on the straights, and would allow the tram to go around standard curves without showing a big ugly gap. For transport it also had to be easy to take the sections apart and for reliable running the connection has to have some flex when the track isn't perfectly level. I managed to do all of that:

Well, at least you were not asking much... (grin) seriously though, those are some demanding targets to hit all of them at once. Pretty impressive.

[Hod Carrier]

That's one splendid tram you have there, sir. I can see where you've had some real puzzles to solve, and you've come through with some fantastic solutions. Chapeau to you.

[UltraViolet]

  From a maintenance standpoint, I feel like these monster-long 7+ segment vehicles must be a maintenance headache.  Just jacking them up off the rails in the depots is an extraordinary undertaking.  You would think it would be better to make them more modular.  In my home city of Toronto, we now have subway trains on one line which are six-car walkthrough units that are not designed to be easily separated.  The other major line uses married pairs that run in six-car sets, but are routinely uncoupled for servicing because the older workshop buildings cannot accommodate the length of a complete train.  The future order specification for new trains on the second line calls for a specially-modified version of the six-car walkthrough trains which will allow them to be uncoupled and driven in pairs within the yards and workshops, due to the existing limitations.  Very interesting from a nerdy technical standpoint!

  I just recently learned about the existence of a different solution to modular trams, and it is quite novel and fascinating.  The TW 2500 variant of the TW 2000 trams in Hanover, Germany, works similarly to the modular walkthrough subway trains I described above.  Basically, they uncouple in the middle at one of the articulation joints for maintenance purposes.  Each vehicle is actually only half a tram, and they only ever operate in service as a coupled pair, but any two 'half' vehicles can form a pair.  It's really cool and weird at the same time!  On a related note, I personally feel that the Hanover TW 2000/2500 vehicles are some of the most strikingly attractive modern trams ever designed.  There's a lot of truly hideous modern trams out there, and these completely blow them out of the water.  I don't think there would be a way to do them justice in a LEGO model, unfortunately, due to shape of the front end and all the curved windows, but I'd certainly like to see someone try.

  BTW, I had solved the problem of the floating sections issue on my five-section Bombardier Flexity Outlook  model (three bogie sections, two floating sections), but I will wait until the model is 100% complete before I try to explain how it works.  The solution was deceptively simple, but it took a lot of screwing around to arrive at.  Also, creating suitable-looking articulation accordions which did not impede the functionality of all of this was a major headache.  The thing that's held me up finishing is the need for a few customized/altered parts to finish the signature front and rear glass.  I got about a third of the way into the work on it but haven't had the time for a while to complete the rest of it.  I'm also hoping to eventually retrofit the worm-drive FX Bricks motor(s) once they are finally released, as the old 9V motors struggle with the weight of the model at low-enough speeds (I had to use three of them for somewhat acceptable performance).

[Duq]

17 hours ago, zephyr1934 said:

The build looks fantastic, you've made some tricky angles look easy

 

Well, at least you were not asking much... (grin) seriously though, those are some demanding targets to hit all of them at once. Pretty impressive.

Thanks! When it's all done it always looks deceptively simple and obvious... which is why I'm getting better at building in iterations. See what works, what doesn't, go at it again.

6 hours ago, Hod Carrier said:

That's one splendid tram you have there, sir. I can see where you've had some real puzzles to solve, and you've come through with some fantastic solutions. Chapeau to you.

That's nice to hear from someone who knows a thing or two about articulation ;-)

5 hours ago, UltraViolet said:

From a maintenance standpoint, I feel like these monster-long 7+ segment vehicles must be a maintenance headache.

There's a lot of truly hideous modern trams out there, and these completely blow them out of the water.  

BTW, I had solved the problem of the floating sections issue on my five-section Bombardier Flexity Outlook  model (three bogie sections, two floating sections), but I will wait until the model is 100% complete before I try to explain how it works.  The solution was deceptively simple, but it took a lot of screwing around to arrive at.  Also, creating suitable-looking articulation accordions which did not impede the functionality of all of this was a major headache.  The thing that's held me up finishing is the need for a few customized/altered parts to finish the signature front and rear glass.  I got about a third of the way into the work on it but haven't had the time for a while to complete the rest of it.  I'm also hoping to eventually retrofit the worm-drive FX Bricks motor(s) once they are finally released, as the old 9V motors struggle with the weight of the model at low-enough speeds (I had to use three of them for somewhat acceptable performance).

Yeah, never though about the maintenance. I'd imagine they have a way to lift out the floating sections and/ or put them on stands. For the Dublin trams they have a purpose-built depot which I think can take in full tram.

Beauty is in the eye of the beholder ;-)  Alsthom have created some... let's say striking designs. Like this hoodie:

I'm telling myself I'm not going to build another Luas any time soon because I have a bundle of other projects to finish first but.... Itching to have a go at those floating sections. Curious to see your solution when you're ready to share.

In Schkeuditz I've seen some steam loco's running on 9V motors and they ran very well. I'm not sure worm gears are the answer though. You will need gearing, but to get going at low speed you probably need a PWM controller like PFx brick. That will give you more low speed torque.

[UltraViolet]

  The trouble with the original 9V train motors is that the gearing is a bit too high for a city street tram.  They can struggle to start smoothly and don't maintain speed well when transitioning into curves with heavier models, hence why I ended up with three of them in my model.  The FX Bricks train motor should help with this because the first gear on the motor shaft is a worm, meaning it should have much more mechanical advantage while bringing the gear ratio down a bit.  It will be of greater quality than the original also.  I am hoping this can at least reduce the motor count to two while still giving me satisfactory performance.  We will see when they ever get released.

[Hod Carrier]

If no-one minds me putting on my professional hat and indulging in the topic drift a little further...

Modern multi-section trams are not expected to be separated except very rarely, maybe once every few years or so for activities such as for routine heavy maintenance or accident repair. The same actually applies to the majority of conventional modern trains also, a significant number of which cannot be split except by a burly bloke with a big spanner. I would imagine that splitting a tram with suspended sections would simply involve putting the suspended section onto stands before removing the kingpin and other connections (air/electrical/hydraulic), and then wheeling the carrying sections away from it.

The limiting factor is, as hinted, the maintenance facilities themselves. Often times, fleet procurement will be tied-in with upgrades to the maintenance facilities, with maximum vehicle/formation length being dictated by, among other things, the length of the shed roads and associated equipment. If an operator is investing in 9-car formations, then you can bet that their maintenance facilities are set-up for this length of tram. Modern maintenance facilities will have things like raised roads, vehicle lifts long enough to deal with full-length formations, in-situ bogie/equipment drop pits and wheel lathes, mobile access platforms and powered hoists which would enable local teams and contractors to effectively strip-down an entire tram.

There are advantages with having trams formed up from pairs of half-sets, but there are also trade-offs and ideally you'd want the fleet to run in stable, fixed formations as much as possible for maximum efficiency. You can have improved availability through increased fleet resilience (e.g. a tram can be reformed while a fault with one half-set is rectified) but it does complicate depot operations due to the increased need for shunting operations and the need to match half-sets at similar points in their maintenance cycles as far as possible.

On the capacity point, longer trams will add capacity as long as the frequency is not reduced. The easiest way to think about it is in cars per hour along a given route. If you double the length of the trams but halve the frequency the capacity remains unchanged. Reducing frequency can also make a service less attractive to users.

[/drift] 

[Duq]

Drift away ;-)

I get the length vs frequency. Based on what I've seen in various cities though, shorter trams seem to run faster. They're probably more expensive to run (you need more drivers) but without a professional hat on it looks like they'd be more flexible in dealing with demand.

And as Dublin found out the hard way soon after the introduction of the 55m trams, if your tram is longer than the bridge in the centre of your city, and you have traffic light either end of that bridge, you end up with a tram  stopped at the lights on one end, while it's tail still sits across some traffic lanes on the other...

Question for your professional hat: you mention a king-pin, but how do those floating section connections work? They need to be able to turn around 2 axes (to make turns and to go over a hump) but not around the third, to keep the floater upright. I'm thinking of having a single connection with two half-beams and a pin, and have that near the top so gravity will keep things vertical, but I'm curious how that's done in real life.

[Andy Glascott]

30 minutes ago, Duq said:

And as Dublin found out the hard way soon after the introduction of the 55m trams, if your tram is longer than the bridge in the centre of your city, and you have traffic light either end of that bridge, you end up with a tram  stopped at the lights on one end, while it's tail still sits across some traffic lanes on the other...

Why am I not surprised by this….? 😂 🇮🇪

[UltraViolet]

  Everything said on this 'drift' I'm in full agreement with.  Such talk is directly up my alley - usually I'd be the one starting the technical rambling!  Hopefully the Mods don't mind a little tram-geek indulgence. 

  I my city, two successive generations of longer trams have been used to progressively reduce service frequency and reduce fleet size.  The longer vehicles now cause backed up queues of trams to form at the entrances to many subway station transfer platforms such that passengers often have to wait many minutes just to be able to exit their tram.  They are also generally operated slower than historically with shorter trams, and they often have to wait an extra traffic signal cycle at intersections because their extra length often can't clear them when traffic is heavy or can't complete turns in a timely manner.  BTW, transit signal priority is a joke in Toronto.

  If a system is designed from the ground up to function properly with longer vehicles, then that is certainly fine.  If there are only a couple long-distance lines operated at high speed with much or total private right of way, perhaps longer vehicles make more sense.  I still say from my experience and knowledge of the inner workings of many rail systems, modularity in the form of shorter vehicles or MU sets, whether coupled in trains or running solo, seems to have far more operational benefit in most cases.  I also feel that any vehicle too long to be lifted by a crane in the event of a major accident really is too long.

[Duq]

4 hours ago, UltraViolet said:

BTW, transit signal priority is a joke in Toronto.

You have transit signal priority? You're ahead of Dublin...

We have 2 tram lines. Roughly a north-south and an east-west. They get to stretch their legs a bit towards the end of the lines, but both go right through the city centre.

4 hours ago, UltraViolet said:

If a system is designed from the ground up to function properly with longer vehicles, then that is certainly fine.  If there are only a couple long-distance lines operated at high speed with much or total private right of way, perhaps longer vehicles make more sense.  I still say from my experience and knowledge of the inner workings of many rail systems, modularity in the form of shorter vehicles or MU sets, whether coupled in trains or running solo, seems to have far more operational benefit in most cases.

I've no professional knowledge or experience, but that pretty much confirms my common sense observation.

[Hod Carrier]

12 hours ago, Duq said:

And as Dublin found out the hard way soon after the introduction of the 55m trams, if your tram is longer than the bridge in the centre of your city, and you have traffic light either end of that bridge, you end up with a tram  stopped at the lights on one end, while it's tail still sits across some traffic lanes on the other...

Whoops-a-daisy!! This is precisely the sort of factor that I was meaning needs to be considered when specifying a new fleet.

12 hours ago, Duq said:

Question for your professional hat: you mention a king-pin, but how do those floating section connections work? They need to be able to turn around 2 axes (to make turns and to go over a hump) but not around the third, to keep the floater upright. I'm thinking of having a single connection with two half-beams and a pin, and have that near the top so gravity will keep things vertical, but I'm curious how that's done in real life.

The main connection and pivot is at floor level and is actually quite a simple arrangement. It does have a certain amount of "float" to deal with pitch and roll as well as yaw so that the suspended sections can move relative to the wheeled sections. There is also a connection at roof level which comprises brackets and a damper to accommodate the additional movement at roof level. You can see the sort of arrangements used on this data sheet from parts supplier Autotechnik GmbH.

8 hours ago, UltraViolet said:

I my city, two successive generations of longer trams have been used to progressively reduce service frequency and reduce fleet size.  The longer vehicles now cause backed up queues of trams to form at the entrances to many subway station transfer platforms such that passengers often have to wait many minutes just to be able to exit their tram.  They are also generally operated slower than historically with shorter trams, and they often have to wait an extra traffic signal cycle at intersections because their extra length often can't clear them when traffic is heavy or can't complete turns in a timely manner. 

I agree. I think that a 5 car formation is more than adequate for on-street running as it can carry a good number of passengers while still being wieldy enough to operate in that environment. But even so, the real weakness of any tram system is where they cannot be fully segregated from road traffic. It only takes one idiot to block the tram lane and you get chaos.

Mind you, queued trams is not unique to systems with excessively long trams, as I've seen a big queue of trams stacked up at a pinch-point on the Croydon system, and their trams are only 2 cars long.

8 hours ago, UltraViolet said:

I also feel that any vehicle too long to be lifted by a crane in the event of a major accident really is too long.

I am not sure precisely how it was done when there was a derailment at Croydon in 2016, where a tram overturned killing seven passengers and injuring many others, but from news videos it would appear that the accident site could not even be accessed by the crane eventually used for the recovery. The tram was somehow righted and put back on the rails and moved back down the track to where the crane and recovery vehicles had suitable access, whereupon the aforementiond burly blokes with big spanners split the unit into it's constituent parts before it was craned onto trailers for removal by road. I would expect that had the same incident affected a longer unit the same approach would have been taken.

It's part of the problem with having fixed formations, and it's not limited to trams. There have been train derailments in Europe and elsewhere involving fixed formation trains, some of which have also overturned and ended up on their sides. Due to restrictions on access, I can't imagine that they could have been recovered as a single formation in one go, but rather were split in situ and then recovered one vehicle at a time.

[UltraViolet]

  Queueing on the Croydon trams??  I made a point of riding the entire system a while back, and I never imagined that was possible with the 'sparse' service at the time (I forget the year of my last trip, but the vehicles still wore the original red-white-black scheme, so pre-2008).  It felt like the once-in-a-blue-moon level of service typical of many transit entities in America.  Maybe rush hour was better.  Has frequency improved since then?  (BTW, when I say entire system, I'm also counting the entire Underground and DLR.  Over the course of my last two visits to London, I've traveled over every bit of every line, including the East London Line before Overground conversion, with the tiny exception of a few minor system extensions/alterations that happened subsequently.  This is a feat 99.9 percent of the locals can't claim, although nor would they want to.  When I describe myself as "committed," I really mean I should be 'committed'. )

  I should note that, in the example of Hanover, the 'half/half' configuration of the TW 2500 must not have been viewed as worthwhile in the end, as it was not repeated in the subsequent TW 3000 model which returned to roughly the same length as the TW 2000.  Another interesting operating approach is San Francisco, where one or two-car trains operate on the street, but couple to form mixed route three or four-car trains when entering the central subway.  The newest cars from Siemens are actually slightly shorter than their predecessors, after the awful Breda cars that were built slightly too long to fit four-car trains in the subway, speaking of a major "Oops".  The Siemens are even shorter than the also 'cursed' Boeings.  (And, yes, as you may have guessed, I've ridden the entire MUNI rail, cable car and BART systems in one trip, again with the exception of subsequent extensions. )

[Hod Carrier]

19 hours ago, UltraViolet said:

Queueing on the Croydon trams??  I made a point of riding the entire system a while back, and I never imagined that was possible with the 'sparse' service at the time (I forget the year of my last trip, but the vehicles still wore the original red-white-black scheme, so pre-2008).  It felt like the once-in-a-blue-moon level of service typical of many transit entities in America.  Maybe rush hour was better.  Has frequency improved since then?

I'm not as much of an aficionado as yourself so I can't really say what the service frequency is now, and this was also a good few years back (although not as far back as 2008). I just remember coming out of Croydon East station and seeing one tram at the stop and two more queued up waiting their turn, although I was on my way somewhere so didn't have time to find out the reason.

19 hours ago, UltraViolet said:

Another interesting operating approach is San Francisco, where one or two-car trains operate on the street, but couple to form mixed route three or four-car trains when entering the central subway.

In the UK that's called "portion working" and is sometimes used on the railways. It's fine so long as one portion isn't delayed, as it can delay all the other portions, and that you don't have any problems coupling/uncoupling. It's also proven to be confusing to infrequent passengers who tend to board the wrong portion by mistake.

[UltraViolet]

  One thing I remember that was quite obviously a problem in San Francisco was the potential for wildly imbalanced passenger loads on multi-route coupled trains in the subway section.  At one point, I was riding Outbound in the PM rush hour, and nearly everyone crammed into the cars of the train that would continue onto their desired route and street destination, rather than boarding a car from another route with a lighter load and hopping to the necessary car at the last station before the exit portals.  I distinctly recall on the crush-loaded cars, multiple passengers actually sitting down in the front stairwell of the Boeing cars destined for the busier route, knowing that the front set of doors would not open in the subway because it did not have the mechanically raised stairs for the subway's high-level platforms (those were only available on the middle sets of doors on those cars).

  It's a striking contrast to the operating model of a very similar system in Boston, the Green Line, where vehicles or two-car trains from a particular route entering the subway section don't couple-up to those of other routes.  They simply all chase each other at the available headway enforced by the fixed-block signaling system.  I had been planning to visit there, but then COVID threw a wrench in that.  In the end, I'm better off going now anyway because the Type 9 vehicles have since entered service.  My personal favorite of the fleet is the Type 7.

  Back on the topic of another Green Line, the Dublin Luas trams, I gather, from what I've read, that the first generation vehicles were built without a provision for coupling into a train.  With that decision constraining service expansion, they later elected to simply grow the length of the vehicles progressively to accommodate increased demand rather than increasing frequency solely through more vehicles.  Once that direction was chosen, the vehicles eventually mutated into the 55m monsters of today.  The Green Line was supposed to have been designed to eventually be upgraded to a full-scale metro, and if this were to occur, the existing trams would likely be replaced.by a metro-style train of larger loading gauge.  The story goes that the line was purposely prepared with a wider track spacing in order to simplify the upgrade.  At risk of sounding poetic, it's kinda like a caterpillar growing bigger and bigger over time, then eventually morphing into a butterfly.

[Duq]

Added some "How it's done" pictures and a better photo of the roof details:

 

[LEGO Train 12 Volts]

I missed this wonder!

I love the modern design of the tram and the new bogies!

You've done a great job!

[Duq]

Thank you!

I've started thinking about a 5-segment version...

[UltraViolet]

  I forgot to come back and post a thanks for the additional photos.  Very nice!

[Man with a hat]

Oh, wow. That's really well done. Again clever work.