Skidding train

I'm having troubles with an AI controlled train not being able to stop completely when facing a red signal.

The downward gradient is 2.5% and although I have given it ample track to slow from 100kph almost to a stop, it's speed never drops below 3kph and it just skids very slowly past the signal, through some closed points and beyond.

After the SPAD, the AI loses the plot and I cannot get it to respond.

I've tried the "AI brake" attachment with no success.

Before I embark on major track re-work to reduce the gradient, is there any other trick I can try to prevent the SPAD?
 
nismit

I am very grateful for your response. I'm sure your analysis is correct and that any of those options would technically work.

As it turns out, I don't think I can use them in my particular case and I might have to accept a re-work of the track. To be explain myself a bit;

- I could edit engine configs, but if I upload this Layout/Session to the DLS, the original engine configs will still apply for anyone who downloads it.

- I could shorten the train, but that would severely reduce the realism of the Session. I have tried using 2 locos per train, but the skidding still occurred.

- I'm only using TRS2004, so the adhesion adjustment isn't open to me.

- I wasn't aware of the trigger rule, it sounds very useful. In this case though, I think trying to stop the train at a point further up the line would meet with the same skidding/SPAD problem since the gradient is the same or worse all the way up this very long climb. If it SPADs, the AI dies and ruins the Session, even if the trains don't have a head-on.
 
I'm having troubles with an AI controlled train not being able to stop completely when facing a red signal.

The downward gradient is 2.5% and although I have given it ample track to slow from 100kph almost to a stop, it's speed never drops below 3kph and it just skids very slowly past the signal, through some closed points and beyond.

After the SPAD, the AI loses the plot and I cannot get it to respond.

I've tried the "AI brake" attachment with no success.

Before I embark on major track re-work to reduce the gradient, is there any other trick I can try to prevent the SPAD?

60mph down a 2.5% grade?!? I am not surprised that the train can't stop! Maybe slow the train to 50kph (30mph) on the grade and see what happens. :o
 
No need to be embarrassed:o . A slower approach speed was the first thing I tried of course. It made absolutely no difference. The train has more than enough braking power and distance to get the speed down from 100kph to 3kph well before the signal, but it just keeps sliding along for miles and miles at a constant 3kph. nismit understands this correctly, it's lack of adhesion not lack of braking.
 
One simple way to avoid this problem is to (in Surveyor) set the points ahead of the heavy train so that they give a "clear route" for the train - in railway parlance the points are then said to "lie Normal" for the train.So when the train approaches the junction the AI won't have to work out the route and the train will not have to stop.On my own "real life" route there is a complex junction at Ryhope Grange approached on a 1 in 250 descending gradient.I placed the signals exactly according to their positions on the OS map but the train simply couldn't stop.The solution here was to move the signal back untril the AI had time to "kick in".
 
Another possibility is the "AI fix", e.g. an invisible braking-engine, made by whitepass (trainz://install/<KUID:58422:100219>). Description:
AI_brake, to use put between two locos, loco and tender, or loco and cars. Adds a lot of braking power to AI trainz.

An example of useing this "AI fix" can be seen in the session of Dermmys Clovis Sub.

Regards

Swordfish
 
lewisner, you'd have to see the layout and the session, but making the signal always clear for the trains coming downhill would screw things up royally.

swordfish, as I said in my intro, I already tried the AI brake device, with no success.

Even without the device, the loco brakes can make the wheels lock up, but this doesn't stop the train because it's skidding along the track, not rolling. The AI device is just more of the same. Works well when the wheels have grip, but useless in this situation.

I have now tried reducing the gradient in the section before the signal. Amazingly (to me at least) it didn't stop even on a piddly -0.5% gradient, just kept sliding along but at 1 kph instead of 3kph.

The only sure remedy was to make the track level, which I've now done.

Thanks everyone for the ideas and discussion.
 
I find that when this happens, I have to issue the Stop Train command to return to manual driver, then put the locomotive into reverse to stop the skid. This works most of the time, so I'm wondering if you could place a command to Change Direction at the point where the train is likely to skid.
 
Dinorius, have you tried the other solution I suggested which is to experiment with moving the signal back from the junction? It also helps if you provide motive power with sufficient braking power to stop the train - for instance if I use an 800 HP Clayton it has little chance of stopping, but if I use 2 X Class 37 it stops easily.
 
nismit

I have tried using 2 locos per train, but the skidding still occurred.


I had this skidding problem but, if not two, then three or four locos per train cured it. But I found it is no good putting more than two locos together. Put numbers 3 & 4 either at the rear or at least a few cars away from number 2.

If the AI-brake did nothing for you, was it because you placed it too close to your locos?
 
important.

ok. how long is the consist? also, consider if you can move the signals back up the slope so they arent in the gradient.

best of wishes,
litlepetslinki
 
Hi Dino

This is a long known bug with TRS06 it has nessitated in many years of building flat yards and passing loops, I once a long while ago spent many days trying all manner of things to fix this, but I just couldn't. However if you check the TC3 features there is a comment in there that may fix the problem "AI Trainz use train brake" hopefully this will fix the problem. But trying to get a comment out of anyone at Auran or Mike10 if it is indeed fixed is like trying to get blood out of a stone.

Cheers
 
ok. how long is the consist? also, consider if you can move the signals back up the slope so they arent in the gradient.

best of wishes,

litlepetslinki

The consist in question is 9 hoppers long. About 1500 tonnes being towed.

Moving the signals/junction further back would not fix the problem. There is no flatter section I could move it to. It's just a long winding climb up the side of a volcano, all at the same troublesome gradient.

My solution was to replace a short section of steep track with several extra kilometres of low gradient S-bends. In this way I could afford to have a completely level section near the signal, and work gradually back up to a steep climb.
 
Hi Dino

This is a long known bug with TRS06 it has nessitated in many years of building flat yards and passing loops, I once a long while ago spent many days trying all manner of things to fix this, but I just couldn't. However if you check the TC3 features there is a comment in there that may fix the problem "AI Trainz use train brake" hopefully this will fix the problem. But trying to get a comment out of anyone at Auran or Mike10 if it is indeed fixed is like trying to get blood out of a stone.

Cheers

Hi Lots

It's even longer known that you think. I'm using TRS2004. I'm not really complaining about this, it's not a bug, it's just what happens when heavy trains are put on steep slopes by idiots who should know better (at least I'm telling myself that).
 
nismit

I have tried using 2 locos per train, but the skidding still occurred.


I had this skidding problem but, if not two, then three or four locos per train cured it. But I found it is no good putting more than two locos together. Put numbers 3 & 4 either at the rear or at least a few cars away from number 2.

If the AI-brake did nothing for you, was it because you placed it too close to your locos?

4 locos on a 9-hopper train would look a tad ridiculous I think! As for the AI brake thing, I tried one, then 2 (near the loco) - no success - then 1 on the rear hopper and 1 on the loco - again, no success. As I said previously, this brake thing is trying to solve the wrong problem.
 
Dinorius, have you tried the other solution I suggested which is to experiment with moving the signal back from the junction?

It also helps if you provide motive power with sufficient braking power to stop the train - for instance if I use an 800 HP Clayton it has little chance of stopping, but if I use 2 X Class 37 it stops easily.

If I place the train on the track, and don't even issue any Drive commands, just let it stand there, it starts slipping at 3kph. I reason that giving it extra distance between the signal and the junction would simply mean it takes longer for it to slide to the junction (having already slid past the red signal).

Your suggestion to use better locos is logical. I'm sort of limited in my choices here. The layout is in Chile or possibly Argentina, so I'm using Chilean locos of which there are 10 or so on the DLS. I've tried them all on this slope and they all suffer the same fate unfortunately.

I'm kinda impressed by the number of possible solutions that have been thought of here. In a practical sense though, I have opted for the one I was hoping to avoid, which is to re-work the track and make a zero-gradient section.
 
That would be your only solution. Apparently, Trainz limits track to wheel adhesion to a set value and can't be changed.
 
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