Since our last Studio Update lots has happened including Christmas, and we hope you had a fantastic holiday and enjoyed quality time with your friends and families. Now the festivities are over and we’re well into February and 2019, I tracked Matt down to see how things have been going and discuss some interesting things they’ve been working on.

This is also a great time to just make it really clear that what we’re showing and discussing in these Studio Update articles are current projects that are deep in development and will almost certainly have areas that don’t meet the quality levels we’re all expecting from final releases. We’re always happy to receive your feedback of course but do keep this in mind when reading on!

Hi Matt, can you believe we’re into February already? Our players would love to know what’s exciting in Train Sim World development right now?

Tons! The team came back after the Christmas break and have been full throttle on various projects.

The major project underway at the moment is our next route, Main-Spessart Bahn, and in response to lots of feedback we’ve received about telling you all more about what goes in behind the scenes, I’m going to sneak an opportunity here to actually tell you a bit about it.

The team have been working on the Main-Spessart Bahn, a really interesting railway line between Aschaffenburg and Gemünden. I want to specifically focus on a few key aspects of this project:

One of the key features of this route is a very steep, in rail terms, 2.1% (1:48) grade that runs continuously for about 4.5 miles in the Eastbound direction. Trains on this route operate generally with a single locomotive at the front and often have very heavy consists behind them that they’re unable to pull on their own. The run up the grade is achieved through the use of “Banking” locomotives and the team have been working hard to make sure this all works and is featured in Scenarios and Service Mode. It’s great fun to run up this grade from either the freight driver’s, or the Banking Loco driver’s, perspective.

Main-Spessart_Banking

Jargon Buster: Banking Locos are normal locomotives that are often used either on their own or in multiples, often on the rear of heavy trains, to provide additional power or braking effort when climbing or descending steep hills.

One area of our routes that we get lots of feedback on is wishing to see improvement relating to the general feeling of life on a route, specifically about traffic on the roads. We’ve been spending quite a bit of time investigating various techniques for this because, while it may appear fairly straightforward to make a car move along a road, doing it efficiently while having a reasonable number of cars on a reasonable number of roads and not impacting frame rate for anyone is really very difficult. However, I’m happy to report the team have had some great success with this and we’re targeting having moving traffic on roads for the Main-Spessart Bahn.

Main-Spessart_Traffic

That sounds awesome and from the early prototypes I’ve seen, it really does help bring the Main-Spessart Bahn to life. Will this be going on any of our earlier routes?

It’s too early to confirm at the moment but there is a strong desire to do this. We are already starting to at how we can get the traffic system on to Long Island Rail Road as a starting point.

What else are we doing to bring life to the routes?

Another really unique area to this route is the dockyard at Aschaffenburg which features some huge machinery for moving cargo and freight around. We’ve made sure these are animating and have great sounds so, when you’re in these areas, the docks will feel alive and operational.

Main-Spessart_Dockyard

The Main-Spessart Bahn route features the Doppelstockwagen (Dostos) vehicles along with the DB BR 146.2, which reminds me of some common feedback we regularly get asked about destination displays on trains. We featured them in the BR Class 101 in Northern Trans-Pennine route, will we see them working in Main-Spessart Bahn too?

Absolutely, now that we’ve moved the bar along and got them in, we’re trying hard to keep pushing things forward and maintain the standard that has been set. The loco and the Dostos have all been upgraded to support destination boards which you can set in the cab using the FT95 control unit. We have an abbreviated set of controls on the FT95 but it will let you set the destinations throughout the displays on the train. We’ve also augmented our service mode so that a service definition in the timetable can now specify which destination is the correct one so that AI trains can set themselves up correctly.

Main-Spessart_FT95

Thanks for that glimpse into some of the work that’s been going on behind the scenes for the last couple of months. Other than the next German route, are there any other exciting projects we can share with our players?

The team are also starting to work on some locomotive add-ons following the very successful Class 33 add-on that Ed Fisk of MeshTools helped us with. We’re continuing to work closely with Ed on a number of projects as well as those we’re working on ourselves. I don’t think we’re ready to talk about them just yet but watch this space, there’s some great content in the pipeline that I think will really excite everyone.

I know that a lot of people reading this are going to be very keen to get an update on where the work is at on the CSX physics work. How’s it going?

It’s going really well. Feedback from the Beta Team has been really positive so far on the GP40-2, SD40-2 and GP38-2 and work has been well underway separately to completely rebuild the AC4400CW SimuGraph setup from scratch.

I asked our Lead Engineer Ben Laws about the changes and he told me “The AC4400CW is the only diesel-electric locomotive we've created that uses AC traction motors. For Rapid Transit, we implemented an AC motor simulation and made some minor revisions to this for later AC motored rail vehicles. However, we found that the equations we used were only really suited to the constant voltage supply on fully electric rail vehicles. The diesel engine in an AC4400CW delivers a very specific amount of power that needs to be passed down to the motors correctly for the whole simulation to work correctly. Additionally, the AC4400CW uses rheostatic dynamic brakes. The setup of this requires a DC chopper, and we did not have a simulation model for this.”

I asked Ben to outline a list of the fixes, but I’ll prefix this with the usual “beware technical jargon below” warning for a Studio Update.

The changes:

Core changes to electric circuit simulation that permits simulation of Current Controlled Current Sources (CCCSs) and Voltage Controlled Voltage Sources (VCVSs). The previous diesel-electric updates allowed us to simulate CCVSs so a lot of the tech was already in place to make this possible. CCCSs and VCVSs are used to simulate things like choppers, inverters and transformers.
New version of AC motors that fix the issues with the equations in previous versions, so power transfer is now far more accurate. We simulate three-phase AC as a line-line RMS voltage for simplicity.
New inverter node that provides a specific frequency and voltage to the motors. This ensures current is calculated correctly on the DC link, meaning the load on the engine is now accurate.
New chopper node that can be controlled based on the voltage value seen on the DC link. This permit redirecting reverse flow current through a braking resistor to dissipate as heat.
New expression node to permit manipulation signals within the simulation through an equation and apply it as an input to another node.
Lots of tuning in the AC4400CW to make use of the new tech to provide an overall far more accurate simulation than what is currently implemented or what would have been implemented had we continued to copy the DC motor setup of other locomotives.
Every area of the physics has received extensive work so I’m confident that you’ll really see the improvements as a result of the work the team have been putting in.

How much is there left to do?

Not much now, once the AC4400CW is completed (which should be any day now) then we’re set for a full round of testing to make sure everything still works together correctly across Sand Patch Grade and Northeast Corridor: New York and then we’ll be in a position to start talking about when a patch can be deployed. We’re very nearly there.

Thanks Matt, all incredibly fascinating and I’m really looking forward to experiencing the finished result. Before I let you go, could I ask you about a topic that our players are dying to know more about? How are things going with the Editor tools?

I knew that was coming! Work continues apace on the Editor with dedicated engineers now busily working on bug fixes and other improvements. We’ve now proven the capability to build a scenario, cook and pack it locally on your machine and get that .pak file added to the main game in the new user content folder structure where the scenario can then be seen and played. It’s a huge milestone and, now that we’re starting to get to this point, I’m confident that we’ll see more rapid progress as the team iron out the remaining issues that get us to our Public Beta launch. I don’t have any more information yet about dates, but we are working on it, it remains a key priority for us and we’re hoping to roll it out as soon as we can.

That’s great news Matt, thanks very much!

Actually, just thought of one more thing! I know our players really like to see those impressive SimuGraph diagrams and it’s been a while since we’ve shared any so here are a couple to show off…

(Open the images in a new tab to get a closer look).

AC44_SimG

The AC4400CW in SimuGraph, now reflecting the changes mentioned earlier.

C33_SimG

And here’s how the Class 33 looks under the hood!

Thanks again for your time, Matt.

So, a busy time in the studio since the last update with team working on not just new content but also moving the core features of Train Sim World along.

In Summary

For those that just want the highlights, here’s the gist of this article:

Screenshots and images displayed in this article may depict content that is still in development. The licensed brands may not have been approved by their respective owner and some artwork may still be pending approval.