Problem with command "Run Around"

obirek

New member
Hi,

first I apologize for starting this thread in case the described problem was already discussed in another. But I searched this forum using problem related keywords and I either get many irrelevant matches or no matches, but nothing that could solve my problem.

The problem I have is that in some situation (about 30% of time) AI driver is unable to complete the command "Run Around". This is the built-in command, <kuid:-3:10083>. This problem occurs in TC version 3.17, build 3233.

As I understand, this command should be performed using the following steps:
1/ Decouple loco from the first vehicle in the consist
2/ Drive forward to a point A
3/ Drive backward to a point B
4/ Coupe loco to the last vehicle in the consist

What happens is that AI driver performs steps 1,2,3 correctly, but fails to complete the last step - it drives back to point A, passing the consist on a nearby track. Then it drives back to point B and continues circulating between points A and B forever, like a pendulum. If track at points A and B was not terminated by a signal, then AI driver would likely to drive off the track and derail.

This problem occurs in some situations only, but I can't really find out what condition causes it. On some yards this command works, on others it doesn't and it is very difficult to tell why.

Very recently I modified track layout in one of my routes. I had a yard with 6 additional tracks, on which AI driver performed "Run around train" command without a problem 100% of time. Then I removed 3 tracks and slightly re-arranged turnouts at the yard ends. After this change AI driver has problem completing this command each time.

I tried to isolate this problem and created a test session, without any additional rolling stock. The command "Run Around" fails each time, despite there were no commands executed prior to this command. This makes me believe that the problem is with the track layout or signalling. But what exactly? If I knew, maybe I could find a way to fix it.

Of course I could substitute "Run Around" by the following commands:
1/ Decouple from vehicle 1
2/ Drive To Trackmark A
3/ Drive To Trackmark B
4/ Couple to vehicle n

But this is complicated and error prone. I could mistakenly select wrong vehicle. Say instead of TRS Tanker 46 I could choose TRS Flatcar 46 and after few minutes discovered the loco miles away from the place it should be. "Run Around" is a very convenient command. But why it does not work?

I would much appreciate any feedback in this matter.
 
Hi obirek, To me it sounds like your buffer termination at point B is too close to the points to allow the loco to clear and change them. Cheers, Bill69
 
Hi obirek, To me it sounds like your buffer termination at point B is too close to the points to allow the loco to clear and change them. Cheers, Bill69

The buffer at point B is about 380 meters and at point A about 250 meters from the point up to which rolling stock can be moved, which is about 54 meters from the turnout. So, the distances are 434 and 304 meters respectively. As I wrote above I had the same yard with "Run Around" command working. After removing 3 tracks the command stopped working. I haven't shortened any tracks.
 
To explain better this problem I made the yard drawing (see below). I apologize for poor quality, but I am not an artist.

So, this is what happens:
- Initially, the train occupies track #8, facing turnout #16. It is at this point I issue AI driver command "Run Around Train".
- AI driver decouples loco from the first vehicle in the consist and drives forward.
- AI driver passes turnout #19 and drives back via track #10. It is at this point I am almost sure that the command is going to fail, as the path chosen by the driver is not the shortest one. The shortest path would be via track #4.
- AI driver passes turnout #10 and turns back via track #4 (instead of track #8 with the consist). It then keeps driving between turnouts #19 and #10 forever.

Few more things I did not include on the drawing to avoid clutter:
- The distance between turnout #19 and the terminating buffer on track #204 is 362 m.
- The distance between turnout #10 and the terminating buffer on track #104 is 588 meters. There is much room for 50 m loco to turn around.
- The minimum distance between any two adjacent turnouts is 10 m in additional tracks and 15 m in main tracks.
- The radius of the trigger is set to 500 m for the turnouts in main tracks (1,2), 350 m in main additional tracks (4), 200 m in additional tracks (6,8,10).


1pfu.jpg
 
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Hi obirek, Ok. the other thing to try is the default direction of the turnouts. I would start with all track 4 turnouts set to straight ahead, turnouts 15 & 16 set to track 8, turnouts 13 & 14 set to track 8. This could cause a delay in the loco getting to turnout 19 but give it a bit of time to change turnout 12 after decoupling. Sorry about the long lines of type but my enter key is not selecting a new line ATM. Cheers, Bill69
 
Hi obirek, Ok. the other thing to try is the default direction of the turnouts. I would start with all track 4 turnouts set to straight ahead, turnouts 15 & 16 set to track 8, turnouts 13 & 14 set to track 8. This could cause a delay in the loco getting to turnout 19 but give it a bit of time to change turnout 12 after decoupling. Sorry about the long lines of type but my enter key is not selecting a new line ATM. Cheers, Bill69

I set default direction of the turnouts as per your advice. What happens now is AI driver passes turnout 12, changes direction and drives to track 4, changes direction again, drives through turnouts 19 and 20 in diverged direction and enters track 2. This is main line track, which should not be used for shunting on real railway. Then AI drives back via vacant track 10 and passes turnout 11. Then it turns back, but just few meters before turnout 11, it changes its direction to track 4 and engages in infinite loop again.

Despite unsuccessful result, I learned that even slight change in the default setting has big effect on how AI driver negotiates tracks in "Run Around" command. I will keep playing with the turnout settings, so maybe I can find an arrangement that works for this particular yard.

Many thanks for giving me this hint.
 
Hi obirek, Yes a bit of experimenting with the turnouts would be good. Also try moving signals. Best of luck. Cheers, Bill69
 
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