Train always wants to roll backwards?

[carlosperea]

Hello everybody. I’ve been lurking for a few months and this is my first post.

I’m currently working on a scenario for the Miami–West Palm Beach route that has 2 ES44s pulling 92 loaded rock hoppers. The ES44s are Steam marketplace CSX repaints of the standalone BNSF ES44DC DLC, and the rock hoppers are 52 of the Hanover Subdivision hoppers and 40 of the Miami hoppers.

While testing the scenario, I noticed that sometimes the rear of the train would start to roll backwards when I released the brakes, and if I didn’t add power I’d be rolling backward at 1-2 MPH. If I went up to throttle notch 1, the front of the train would immediately start moving at 1 MPH, but I’d still see the rear of the train going backwards and eventually it would cancel out the power application and my speed would drop to 0 MPH. This was on a flat 0% grade. When this happened, it would be very difficult to gain speed and the train would eventually max out around 36-38 MPH at full throttle.

Other times, the train would stay still when I released the brakes, notch 1 was enough to get the train rolling, and I could eventually get the train up to track speed of 60 MPH.

I noticed that the cars only seemed to start rolling backwards if I switched to the rear external camera before the front was moving at more than 1 MPH or so.

I did a successful test run the other night. Last night I did another test and the same train maxed out around 47 MPH. I tried again and now I’m having the cars rolling backward problem every time I try to run the scenario again. I’ve tried swapping the locomotives to the Hanover Sub Dash 8 and the Miami Dash 8, but still can’t go any faster than 36 MPH. It’s almost like the cars are actively pulling in the opposite direction.

Unless of course this is just how a real world train like this would behave, but it seems odd that I don’t get the same results every time. Am I running into a limitation of the way the program handles long/heavy trains or is there something I’m doing wrong? I’ve tried clearing the cache, restarting the game, and even deleting and replacing the cars in the consist.

[carlosperea]

Hello again, everyone. I've done some more testing and this is what I've found.

If I release the brakes and do nothing, the train will continue to pick up speed backwards. I let it get as high as 6 MPH and then I uncoupled the locomotives from the consist to see what would happen and the consist immediately stopped moving. This is a two part scenario and I've had the same problem at two different starting locations. I don't think they're rolling downhill since this is Florida and there aren't really any hills to speak of.

I wondered if maybe there had been some sort of physics upgrade to the standard ballast hopper between the 2014 Miami route and this year's Hanover route and the interaction between the two sets of cars could be the culprit, so I made a consist of just 92 Miami hoppers but had the same problem.

I tried adding more horsepower to see if that would help. I replaced the ES44s with AC6000CWs but even then the pull from the hoppers would bring the train to a stop at notch 1 and it would never accelerate any further.

I tried using 3 locomotives and replaced the ES44s with C40-8Ws and it seemed to work. During this test is when I noticed that the performance of the train seems to depend on how quickly I can get the train moving before the backwards sliding cars pick up momentum. If I release the brakes and wait before applying notch 1, the train accelerates slowly and tops out around 40 MPH after 12 miles. If I release the brakes and immediately go to notch 1, the train accelerates slightly faster and tops out around 50 MPH after 8 miles. If I release the brakes and immediately throw it into notch 2, the train runs much faster and I can get it to 60 MPH within 6 miles.

So I'm guessing that there's something wrong with these ballast hoppers, maybe something to do with the couplers that's causing them want to constantly push backwards? I've never really noticed it until now that I've tried running longer trains, but for now it looks like it can be overcome by simply getting the train moving forward as quickly as possible before the consist has time to build up enough rearward momentum.

Has anyone else encountered a similar problem?

[bnsfsubdivision]

In short, welcome to TS' unfortunately bad core physics.

[BNSFdude]

Between the couplers and loadable open hoppers, the game is just wack. This is why we and G-TraX typically have loaded/empty variants of cars.

[GreatNortherner]

...Has anyone else encountered a similar problem?

Yes, I have -- what you've described sounds very familiar indeed.

We stumbled over this while building the equipment for the RWA Lakeside route. We tested various things and narrowed it down to the culprit being in the wagon blueprint's "cargo component". This has a mass setting (labeled "capacity" in the blueprint) and when this gets too large, the rail vehicle physics start misbehaving. In our tests, we've started seeing bad results with cargo masses as low as 50 tons, if I remember correctly -- which is of course far less than what a modern US freight car typically carries.

That's why we switched to setting up all cars as duplicate "empty" and "loaded" versions, just as BNSFDude mentioned, where we can configure the entire car's mass in the RailVehicle Component section in the blueprint which doesn't appear to be affected by this bug.

I'm afraid that won't help you much with your scenario though. But maybe you can swap the offending rock hoppers with RW_Tools for cars from somewhere else that are set up as loaded and empty cars?

Cheers,
Michael

[carlosperea]

On the bright side, it’s a relief that it’s not anything I’m doing wrong. I was so confused because I swear CSX managed to run these trains with 100+ cars and two engines just fine.

This also explains why there are no scenarios for this route featuring rock trains this long. In the end I “solved” the problem by throwing power at it; I have 4 Dash 8s on point now but I can get the train up to a decent speed.

Since I was planning on publishing the scenario to the Steam Workshop I kept it to just the basic rolling stock but tonight I’ll experiment with different hoppers from other sources for my personal use.