I am creating this discussion to highlight potential problems in train physics simulation, particularly rolling resistance, with the aim of enabling developers to adjust certain trains that lose speed too quickly. To this end, I am sharing the results of a series of tests I have just conducted. Below, I will detail the procedure for those who wish to contribute further results using other trains. For my tests, this involves measuring the loss of speed while coasting on flat ground at 50 km/h, over a distance of just over a kilometer, between two markers on the training center circuit. Results: (arrival speed in km/h) - ICE 4 BR 412 12c 675t --> 47 - ICE 1 BR 401 14c 847t --> 47 - ICE 3M BR 406 8c 435t --> 47 - BR 642 4c 139t --> 46 - Class 170 3c 139t --> 45 - Class 378/2 5c 209t --> 45 - Class 375/9 4c 173t --> 45 - Class 377/2 4c 168t --> 45 - Class 333 4c 185t --> 44 - Class 220 Voyager 4c 188t --> 44 - Class 165 2c 81t --> 44 - Class 700/0 8c 272t --> 44 - Class 150/2 2c 77t --> 44 - Class 350/1 4c 175t --> 43 - BR 442 3c 114t --> 43 - ICMm3 (Dutch) 3c 144t --> 42 ------ ------ - OBB 4024 4c 116t --> 41 - Class 710/2 4c 151t --> 41 - BR 425 4c 114t --> 41 - BR 440 4c 114t --> 41 - Class 385 4c 158t --> 40 - BR 423 (423 876) 4c 119t --> 40 - Class 331 4c 142t --> 39 ------ ------ - BR 423 (423 096) 4c 132t --> 33 (Old version of 423 I think) - BR 430 4c 132t --> 33 - SNG3 (Dutch) 3c 110t --> 31 - ICE T BR 411 7c 370t --> 9 (yes, only 9 km/h) It appears that the physics for the BR423 were updated at some point, which is why I have two very different sets of results. Then I divided the ranking into three parts: the top section represents what seems normal to me, the next part covers what seems a bit less normal, and finally, there are the trains that clearly have a major problem. At this speed, I don’t believe there should be such a large gap between the trains, given that rolling resistance is in reality extremely low, and air resistance is relatively low at this speed. Moreover, if we focus solely on the trains from the United Kingdom, we can see that two of them fall into the second part of the rankings, far behind all the others. Maybe these two trains have a slight issue in terms of simulation, but the others UK trains on the top section are very close, regardless of their size and weight, and that's exactly what I expected.
For those who wish to supplement these results with trains that I have not tested, here is how I proceeded: On the "high speed" circuit of the training center, I used the inner track, exactly as in the Class 333 introductory tutorial. For those who do not have the 333, we start from the Station at platform number 2, towards the stairs which allow crossing the tracks, so by traveling the circuit by turning left, on the left track. When you take the circuit this way, there is a first long left turn, then a straight section, then a second long left turn going through the tunnel, then another straight section for the return to the Station, to platform number 2. So depending on the train you choose you sometimes have to maneuver switches through the training centre to take this same route. The measurement process is simple: the starting point for the 50 km/h check is the tunnel exit, and the endpoint is the far end of the station platform. Personally, I approach the tunnel at around 50, slightly below, once in the tunnel I accelerate slightly to reach 51, then I cut back hoping to drop to 50 at the end of the tunnel. If I drop to 50 a little before or a little after, I record the final speed a little before or a little after the end of the platform. There’s no need for meter-perfect precision, it’s more than enough to highlight the glaring anomalies one notices while playing. In fact, this test confirmed the doubts I had regarding certain trains. If you also have doubts about a train that does not appear in this list, feel free to test it in the same way and report any potential issues to the developers, so that the game can be improved.
