Train Sim World
Train Sim World 2 – Building The TGV Duplex
In our second developer feature, we find out more about the star of LGV Méditerranée...
Tell us a little about yourselves, what do you do here at Dovetail?
Peter: I am the Senior Technical Designer. As part of the rail vehicle set up team, my job is to create the locos technical perspective, including simulation and functional elements.
What I do is essentially bring all the visuals into something that can actually be used and interacted with. Such as the buttons, levers and everything in the cab. I then add all the set up to control the systems such as animation and lighting.
James: I am the Senior Physics Engineer. I use our team's tools to make the physics for pretty much every train we are creating. I created all of the initial block out and I’ve done all of the air systems and the brakes. There are an amazing four different braking systems on this train.
It was my responsibility to ensure all the systems work and integrate together, there’s a lot of blending between systems. For example, the electrical system and the characteristics of the electric brake is part of this which then gets blended with the air brake system.
How do you start making a new locomotive?
Peter: That’s a difficult question to answer because of the amount of detail that goes into a loco. Our initial steps are research. We have to figure out everything we need and want to implement. Which includes identifying all the controls and their behaviors as well as the more technical underlying elements such as power systems any safety systems or brake operations. All the electrical and air related systems under the hood, how the controls manipulate and drive all of that.
Once we have that information the development process is to then start creating all the controls and tie them in to the functionality of all the other components.
Why is the initial model bright pink?
Peter: When we first get the model from the artists it is just the basic mesh. No texturing, no materials or anything like that. And the way unreal engine shows an untextured asset is just grey, an extremely bland monotone grey that you can’t see any detail in.
Pink is a great contrast colour that we can apply to it to see some of the details of the mesh and it makes it easier for us whilst working to place the initial controls before the more detailed model gets in.
Is there anything unique about this loco and the game play?
Peter: This loco has four different safety systems. TVM (Transmission Voie-Machine), KVB (Contrôle de vitesse par balises), Crocodile and VACMA (Veille automatique)
The TVM highspeed in cab signaling system allows trains to travel over 300km/h. KVB in cab signaling system works with the local colour light signals. Crocodile is a more basic signaling system that alerts the driver to warning or danger signals. And VACMA is a vigilance/warning system that keeps the driver alert and in the seat, while driving.
James: The TGV has a combined throttle and brake handle, which primarily uses electric braking, but also blends in local air brakes on the power cars as well at low speed.
It has a train brake system using an air operated PBL (Presse Bouton Locomotive) brake handle which runs with EP (Electro-Pneumatic) assist. This applies air brakes across the whole train, but using EP to speed up brake applications and releases. There is a backup air brake system (without EP) should the PBL or EP systems fail.
The main difference that will be felt is high-speed content tends to have a different gear ratio so you end up with relatively slow acceleration but much higher top speeds. Going this fast definitely effects the game play, there’s a series of things we’ve done to ensure that the game loads scenery fast enough to guarantee you don’t run out of world.
The other thing of course is all the huge distances covered, because when you are doing 300 km/h it takes a vast distance to stop. Planning ahead is vital for this kind of route.
What is Simugraph?
James: It is a graph-based approach to replicating essentially all the traction braking and power systems that represent an individual rail vehicle. It is a simulation of a real-world physics environment.
We might create for example an air reservoir, which is an air tank, and then that will have an amount of air in it which will create pressure. We can then create a pipe from there to another one, and a valve so you can turn it on and off, and as we turn it on air will flow through and it will calculate how it balances out between the two reservoirs. We start with things like that and then expand to some quite complex systems.
Peter: The TGV is comprised of about 100 different nodes within Simugraph which defines the characteristics as simple as the axles and brake pads to the more detailed complicated electronic systems like the current collector for the pantographs.
Have you come across any challenges while creating this loco?
Peter: There’s always challenges when it comes to doing the research for locos, this one in particular, although we have done it previously with Train Simulator the amount of detail we can go into this time means we are essentially doing the research from scratch to ensure we haven’t missed anything, and to gather new information.
James: I think getting to grips with support for multiple voltages, and although that’s not so much a challenge it is new technology and we haven’t had this ability before now. We’ve built one multi voltage train previously, but we had two different systems there and not two different voltages via the same system.
One of the biggest challenges for us was actually understanding French. All of the manuals are in French so when we wanted to read about it, all of the information we wanted was in French. This is one of the disadvantages of going into the depth and detail we do to get everything right. Beyond the fact we speak little French, on occasion we were trying to translate some very technical terms, which wouldn’t normally come up in a standard conversation.
Missed our first behind the scenes look at building the route for LGV Méditerranée? Read that here. Over the coming weeks we’ll be looking at some of the features on the route and sharing more screenshots. Make sure you’re following @TrainSimWorld on Twitter and Facebook for regular updates.
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Train Sim World
Train Sim World 2 – Building The TGV Duplex